UNIVERSITY OF KANSAS ^'mmL^i^ATfoM MUSEUM OF NATURAL HISTORY No 52

MUS.

APf? 1 4 1975 Harvard

A Demographic Study of the Ringneck Snake (Diadophis punctatus) in Kansas

By Henry S. Fitch

UNIVERSITY OF KANSAS LAWRENCE 1975 April 3, 1975 UNIVERSITY OF KANSAS PUBLICATIONS MUSEUM OF NATURAL HISTORY

The University of Kansas Publications, Museum of Natural History, beginning with volume 1 in 1946, was discontinued with volume 20 in 1971. Shorter research papers formerly published in the above series are now published as Occasional Papers, Museum of Natural History. The Miscellaneous Publications, Museum of Natural History, began with nimiber 1 in 1946. Longer research papers are pub- lished in that series. Monographs of the Museum of Natural History were initiated in 1970. All manuscripts are subjected to critical review by intra- and extramural speciaHsts; final acceptance is at the discretion of the publications committee. Institutional libraries interested in exchanging pubhcations may obtain the Occa- sional Papers and Miscellaneous Publications by addressing the Exchange Librarian,!i University of Kansas Library, Lawrence, Kansas 66045. Individuals may purchase separate numbers of all series. Prices may be obtained upon request addressed to Publications Secretary, Museum of Natural History, University of Kansas, Law- rence, Kansas 66045. The University of Kansas Museum of Natural History

Miscellaneous Publication No. 62

April 3, 1975

A Demographic Study o£ the Ringneck Snake (Diadophis punctatus) in Kansas

by

Henry S. Fitch

Department of Systematics and Ecology Natural History Reservation The University of Kansas

The University of Kansas Lawrence 1975 University of Kansas Publications, Museum of Natural History

Editor: Richard F. Jolinston

Miscellaneous Publication No. 62

pp. 1-53; 19 figures

Published April 3, 1975

Museum of Natural History The University of Kansas Lawrence, Kansas 66045 U.S.A.

Printed by University of Kansas Printing Service Law^rence, Kansas CONTENTS

ABSTRACT 4

INTRODUCTION ...... 4

Acknowledgements 5 Materials and Methods 5

Morphology 8 HABITAT 11

BEHAVIOR 12

TEMPERATURE RELATIONSHIPS 18

SEASONAL SCHEDULE 19 ASSOCIATED ANIMALS 20 FOOD HABITS 22 SPATIAL RELATIONSHIPS 24 REPRODUCTION 27

Aggregation and Mating 27

Reproductive Cycles 28 Eggs 29

Size of Clutch 29

Reproductive Effort 31 Nests 32 GROWTH 33 POPULATION DENSITY 39 COMPOSITION OF THE POPULATION 43

Age Structure 43

Sex-ratio 45 PREDATION 47 DISCUSSION 50 LITERATURE CITED 52 ABSTRACT

Field records of more dian 14,000 individuals of Diadophis piinctatus were assembled over a 26-year period on several small study areas at the University of Kansas Natural History Reser\ation, mostly within a half-mile radius, with emphasis on marking and recapture. Emergence from hibernation begins in late March and continues into early April, ovulation occurs in the latter half of May, and the elongate, sausage-shaped eggs, averaging approxi- mately 3.9 per clutch, are laid in late June or early July. Hatching occurs at the end of August or in September. Females become sexually mature after their third hibernation, typically at a snout-vent (S-V) length of approximately 235 mm, but males mature a year earlier, at a min- imum length (S-V) of 166 mm. Growth continues, but at a reduced rate, after attainment of sexual maturity. Snakes already above average adult size typically gain from one to three per cent in length annually. Mortality of adults is not age-specific, and loss is approximately 25 per cent annually. A small percentage of the snakes survives to an age of 15 or more years. Young seem more secretive than adults and are less well represented in samples. Sex-ratio in samples is subject to drastic seasonal fluctuation; females range from 24 per cent in early fall to 71 per cent in midsummer, but in late March, April and early May, when the snakes are most in evidence, males are always more numerous. The snakes are active over a wide range of temperatures but tend to maintain body temperatures between 25 and 29.5 degrees C. Their surface activity is chiefly at air temperature witliin or below this range, and at higher air temperatures they retreat underground. Body temperature is maintained by con- tact with sun-warmed objects that the snakes use for shelter. Occasionally, at relatively low air temperatures, the snakes venture into the open and bask in sunshine. Earthworms, especially AHoIohophora caliginosa, provide most of the food, and it is esti- mated that each snake consumes on the average approximately three times its body weight in earthworms annually. Seven calculations of population density (based upon recapture ratios) varied from 719 to 1849 per ha and averaged 1266. Eight kinds of predators on the Reser- vation were found to eat ringneck snakes, but their toll would account for only part of popu- lation regulation. The copperhead, racer and Red-tailed Hawk were the predators in most recorded instances, but moles, mice and birds other than raptors may also be among the im- portant predators. Marked snakes were recaptured at distances of zero to 520 m from the original capture site; however, one-fourth were within 10 m, even after intervals of several years, showing a strong tendency to remain within a home area. Home ranges were often elongate, with maximum axes of approximately 140 m. Ranges tend to be progressively altered through time. INTRODUCTION

The ringneck snake (Diadophis piinc- as a consumer of invertebrates and as an tatus) is a highly successful transconti- abundant food source for larger preda- nental North American species. Its local tors. In the ensuing 26 years the species populations are adapted to the swamp- has been allotted more time and effort land of subtropical southern Florida, the than any other kind of animal in the boreal forest of heavily glaciated areas many autecological studies carried out in northern Michigan and the desert on the Reservation. grassland of the southwestern United This small snake has proven to be a States. Partly because of retiring or se- difficult subject for field study, despite cretive habits, the species is considered its great abundance. Individuals ordi- rare throughout most of its extensive ge- narily cannot be observed readily under ographic range. However, in a central natural conditions. When uncovered or area including northeastern Kansas, discovered in the open, they are glimpsed where my study was made, it is abun- only momentarily, escaping underground dant and ecologically prominent. or into dense vegetation. The snakes Soon after field work began on the cannot be found for most of the year, newly-created University of Kansas Nat- including, of course, their hibernation ural History Reservation, the ringneck season. But they are also difficult to find snake attracted attention as one of the in summer, especially in hot and dry common animals meriting intensive study weather. because of its probable ecological roles The present study had its inception FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE

and in the spring of 1949 when I began tak- eleven-year period, was supple- mented 15 accumulation of ing field notes on ringneck snakes and by years' individually marking those that were earlier data. Expenditure of so much time and on a local of captured. In the 1950s the snakes were energy population observed or marked only occasionally, one species may appear prodigal; yet, the records that were the as part of a comprehensive program to recapture key study the vertebrates of the Reservation. to an understanding of ecological rela- Several students at different times under- tionships and population dynamics to- a few and when took ecological studies of Diadophis in talled only hundred, the area: John Hawken (1951-1952), these were subdivided into sexes and Robert M. Hedrick (1956-1957) and ages, some samples were inadequately Kenneth Shain (1958-1959). Hawken's small. and Hedrick's records were mostly from the Rat Ledge area, whereas Shain's Acknowledgments were from the vicinity of the Reservation Members of my family, Alice Fitch headquarters. Although each of these Echelle, Chester W. Fitch, John H. projects was of short duration, their Fitch and Virginia R. Fitch, helped me combined data contributed substantially from time to time, both with the field to my study. work and with various stages in the In the spring of 1964 large-scale cap- analysis of data. Many persons helped ture and of was un- marking Diadophis in the search and capture of the snakes; dertaken at Rat in the field near Ledge, Robert R. Fleet's contribution of many Reservation headquarters "House Field," large series was especially outstanding. and in Field" the northern "Quarry along John Hawken, the late Robert M. Hed- of the Reservation 1 . On 24 edge ( Fig. ) rick, and Kenneth Shain each contrib- a was initiated September 1965 system uted data accumulated from one or more for the of recording pattern pigmentation seasons of field work. Donald R. Clark, on the ventrals to posterior supplement Robert W. Henderson, Richard L. Lattis, the clipping of scales as a means of posi- Julian Lee, Michael V. Plummer, Eric tive individual identification. In 1966, Rundquist, and Arnold K. Smith were at Rat were abandoned operations Ledge employed as research assistants at differ- and field work was concentrated in the ent times, and all contributed substan- House Field and Quarry Field areas, while tially. In 1971, 1972, and 1973, which were close that snakes enough engaged in his own field research on the often shifted from one to the other. Reservation, Lattis captured and con- The marking program was suspended tributed many ringneck snakes marked at the end of May, 1968, but in the in 1969 or before; these long term sur- of 1969 all spring first-year young cap- vivors provided some of the most reveal- tured were and those group-marked ing records of longevity, growth, and considered were yearlings individually population structure. Financial support marked in an eff^ort to gain more infor- from the National Science Foundation mation the of In of about growth young. (6-17084) and from the University the fall of and in 1970 1969, through Kansas is gratefully acknowledged. 1974, efforts to capture the snakes were continued; those taken were not marked Materials and Methods but were measured, weighed, sexed, and In snakes were found carefully examined for marks made in spring ringneck numbers beneath flat rocks, es- the period 1958 through 1969. Hence, in large in woodland or at wood- although procedures and areas have var- pecially open at ied somewhat from year to year, my in- land edge, hilltop edges including "Rat and an old tensive field study extended over an "Skink Ledge," Ledge,"

I 6 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY

500 m

Fig. 1.—Contour map of northwestern part of The University of Kansas Natural History Resei-vation showing study areas of Diadophis punctatus, 1949 to 1974. A. "Quarry Field," a flat hilltop with tall grass interspersed with brush. B. Abandoned limestone quarry at south exposure of hilltop edge. B 1. Hibernation site for snakes from both hilltop and valley, limestone outcrop with southwest exposure. B 2. Egg- laying and "nursery" area at east end of quarry. C. "House Field," at head of small valley. D. "Rat Ledge," limestone outcrops at hilltop edge with south exposure. FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE

rock quarry, where suitable flat rocks The ringneck snakes captured were were numerous. In 1966 and 1967 funnel processed in the field during the early traps were used on a large scale. These years of the study, but during most of were adaptations of the cylindrical wire the study period snakes were brought to funnel traps used earlier in population the laboratory. Processing consisted of studies of larger kinds of snakes at the probing for the invaginated hemipenes Reservation (Fitch, 1951; Clark, 1966). in the tail base to determine sex and A glass quart far served as the trap body; measuring the snout-vent (S-V) length a funnel of 1/8 inch mesh screen was sol- and tail length to the nearest millimeter. dered to the screw-top of the jar. These For the snout-vent measurement the traps were used in combination with snake was held against a rigid ruler and drift fences consisting of strips of sheet gently pulled out straight for several metal 2 to 6 m long and 25 to 38 cm seconds until muscle fatigue caused it to wide, buried to a depth of at least 5 cm, relax momentarily, permitting stretching so that snakes could not readily pass be- to the maximum length. The accuracy of neath. A funnel trap was set at each end measurement was checked in a random of the barrier, and traps were generally sample of 200 adults recaptured within situated in clumps of grass or other dense a two-week period—too short an interval vegetation, so that captured animals for the snake to make measurable growth. would not be exposed to direct sunlight. Mean deviation from the original meas- urement was 1.52 0.6 Strips of sheet metal that were left mm, approximately cent. lying in grassy places from time to time per were found to have groups of ringneck Snakes captured were individually snakes congregated beneath them. A se- marked by scale-clipping, in a modifica- ries of tion of the Blanchard and Finster 1933 such experiences brought belated ( ) realization that formerly pastured grassy system. Three scales were clipped on fields harbored high populations of ring- each snake to attain a unique combina- neck snakes with densities comparable to tion; the left or right end of one of the those in the rocky upper-slope and hill- posterior ventrals was clipped out, also top habitats. Subsequently, large num- one subcaudal on the left side and one bers of sheet metal strips and weathered on the right were partly or wholly ex- boards were distributed over study areas cised. The subcaudals clipped included selected in House Field and Quarry numbers 2 to 20 on each side, counting Field, and collectively these objects posteriorly from the vent. On each side served as highly effective traps. Success- the count began with the first scale that ful use of these devices as traps de- made contact on or near the midline pended upon proper timing of field work. with a counterpart on the opposite side; The snakes were attracted to the metal smaller scales just behind the vent, chiefly in cool weather, when the metal which did not extend to the midline, was warmed by sunshine but air and were not included. substrate temperatures were lower than Snakes have some capacity to regen- the snake's preferenda. However, at erate lost or damaged scales (Conant, most the times metal was uncomfortably 1948) and this capacity seems especially hot or cold to the snakes and was well developed in Diadophis. The scars avoided. The boards provided better in- left by clipped scales often became ob- sulated hiding places and were used at scure after several years. Regeneration certain times when the metal strips were of the scale surface was sometimes so unattractive. The boards and metal complete that partial fusion along a su- strips proved to be so effective for cap- ture or a break in the sequence of pig- ture of the snakes that use of funnel mented dots on the subcaudals provided traps was discontinued after 1967. the only clues. Examination of the scars 8 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY under a dissecting microscope often was small and rhomboidal, 2 preoculars and necessary before identification was made. 2 postoculars on each side, one anterior Natural scars on the tail were common and one posterior temporal, and 7 supra- fourth in contact and were a potential source of confusion. labials, the third and Bites of small predators such as Blarina with the eye. There are 15 or 17 scale brevicauda caused indentations that rows, each body scale with an apical pit, sometimes were mistaken for those made anal plate divided; eye with round pupil iris. The by clipping scales with scissors. and golden-brown following in a Because of these potential sources of are ratios to snout-vent length typ- confusion or error, it was necessary to ical adult male: tail length, 24.50%; head supplement scale-clipping with other length, 4.38%; body diameter, 2.14%; di- means of identification. Such means was ameter of eye, .63%; length of longest provided by the variable pigmentation ventrals, .67%; length of longest dorsals, of the ventral surface. Markings on the .56%. The teeth are slender and conical, most fre- posterior ventrals (numbers one to ten with the following numbers anterior to the anal plate) were classi- quent on the bones that are dentigerous: fied as "bars," "blotches," "spots," and dentary 16 (or 17), maxillary (Fig. 4) "dots" according to their size and shape. 13 (or 14), pterygoid 10 (or 9), palatine The number and position of such marks 20 (or 21). In the dentary series the on each posterior ventral was recorded. anteriormost tooth is relatively small and In many instances positive identification slender, the second less so and the larg- was based on the ventral markings when est are those a little anterior to the mid- it could not have been derived from the dle; farther posteriorly the teeth are scars of clipped scales alone. progressively smaller and more recurved. Weight was recorded to the nearest one-hundredth of a gram. Laboratory balances were used until 1969 when Oskar Ludi spring scales became avail- able and greatly expedited weighing. Obvious bulges in snakes were palped up to the gullet for identification; and when intact they were removed from the snake for weighing and/or measurement. Reproductive condition was noted. In females of adolescent size, thickening of the cloaca indicative of sexual matu- rity was recorded. A drop of normal saline was pipetted into the cloaca, and a smear was taken and examined for motile sperm under magnification x 60. Mature snakes of both sexes often had great c^uantities of sperm in the cloaca. In the male its presence was considered indicative of breeding condition, and in the female it was considered indicative of recent copulation.

Morphology

Characters of the local — population. Fig. 2.—Head of adult Diadophis piinctattis The head scutellation is colu- typically armji showing scutellation and pattern; top, brine (Fig. 2), with nasal divided, loreal lateral; center, dorsal; bottom, ventral. FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 9

Table 1.—Tail Length as Percentage of Snout-Vent Length in Male and Female RiNGNECK Snakes of Different Size Classes. For Each of the Eight Samples N = 25.

Size Class Males Females

Large adults 22.1 ±: .315 (25.4-20.8) 17.9 ± .201 (19.7-15.3) (males 298-272 mm, females 347-300 mm)

Typical adults 23.2 ih .323 (25.9-20.7) 17.9 ± .217 (19.8-15.9) (males 249-240 tum, females 289-270 mm)

2nd year young 21.9 ± .069 (23.0-20.9) 17.3 ± .154 (19.1-15.6) (189-170 mm)

1st year young 20.8 ± .345 (25.2-17.8) 17.1 ± .248 (18.6-15.4) (128-111 mm) with the smallest only about one-third than do young. In males this ontogenetic the size of the largest. In the maxillary change in relative tail length is three series the anterior teeth are relatively times as great as in females. In the larg- long, slender and erect, and those far- est males the trend is reversed and rela- ther back are stouter and directed more tive tail length is a little less than in posteriorly. The last two of the series smaller individuals. There is overlapping are almost side by side and are stouter between the sexes in relative tail length

in the 12% . and more backward pointed than the only first-year young ( ) others, and they are separated from the Trends in size, as indicated by snout- next anterior tooth by a space about vent length and weight, are shown in equal to the length of that tooth. The Table 2. In this table the figures for the palatine teeth are small, about half the largest adult and the smallest sexually size of the maxillary and dentaiy teeth, mature snake are based upon single in- with marked decrease in size posteriorly. dividuals, and hatchling size is based 83 of 21 clutches hatched in Relative tail length is subject to con- upon young All other are siderable individual variation and also is the laboratory. figures based with 100 or subject to sexual difference and onto- upon larger samples, more snakes in each. genetic difference. In 200 randomly se- lected individuals with intact tails, tail The body color is dark bluish olive length varied from 15.3 to 25.9% of snout- dorsally, the head darker than the body. is vent 1 . all males behind the head a or length ( Table ) At ages Just pale buffy have relatively longer tails, and adults of dull orange band VA scales wide, edged both sexes have relatively longer tails with black both anteriorly and posteri-

Table 2.—Sizes of Male and Female Ringneck Snakes of Different Age Classes in A Local Population

Male Female

Length S-V Weight Length S-V Weight (mm) ( grams ) (mm) ( grams )

Largest adult 315.0 9.0 391.0 Average adult 253.6 5.4 281.7 7.0 Young adult (3rd year) 223.0 3.9 243.8 5.0 210.0 3.5 Smallest sexually mature 168.0 2.0 2.8 Average 2nd year young (in spring) 184.6 2.3 194.1 1.05 Average 1st year young (in spring) 122.6 .97 127.0 Hatchling 109.3 .74 114.1 .81 10 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY

orly. On the side of the head the sepa- ration of the darker dorsal color from the paler ventral color is accentuated by an irregular black band along the upper parts of the supralabials. The chin is cream-colored or buffy, speckled with black, and gradually brightening to yel- low on the neck and more posteriorly on the ventral surface. The ventral yellow has some orange suffusion which be- comes much more prominent on the tail. Black spots are prominent on the ventral surface, and may be arranged in a fairly regular mid-ventral row or may be paired or irregular. Ventrals usually have black areas in their lateral corners. Fig. 3 shows six types of common ventral pat- terns, but intermediate stages occur, and usually two or more of the types shown are present on the same snake. In a ran- dom sample of 200 snakes mid-ventral spots ( type A ) were most common, with followed 44.0%, by paired spots ( types B and C) with 40.7%, blotches and bars (type F) with 6.9%, irregular marks (type D) with 6.0%, and unmarked (type E) 2.4%. The subcaudals have black in the corners and lack other marks.

The hemipenis (Fig. 4) consists of a shaft, and a capitate part which com- prises the distal one-fourth. The capitate part is slightly constricted at its base, slightly expanded and shallowly bilobate, with many large and irregular pitlike depressions (calyces). The shaft, except for the part near the sulcus, is covered with spines which are variable in size and distribution and are thick and Heshy except at the tips. The sulcus spemia- ticus is bifurcate distally. Geographic variation.—In the popu- lation studied, much individual variation was found in characters that have been reported to vary geographically and which are the bases for recognition of the many subspecies of Diadophis punc- tatus. Characters that are notably vari- FiG. 3.—Six types of ventral patterns common in snakes of The University of Kansas able are: body size, dorsal color, ventral ringneck Natural History Reservation. color, size and shape and distribution of black markings on ventral surface, pres- mg on facial region, number, of dorsal ence and width of neck ring, black mark- scale rows, number of ventrals and sub- FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 11 caudals and number of supralabials. The change from body to tail. In others, es- population studied is centrally located in pecially those in which the tail-spiralling the geographic range of the species, and response is highly developed, the under- is intermediate relative to other popula- side of the tail is coral red. Scales are tions in some of its characters but is near in 15 or 17 rows in the Kansas snakes the extreme in some others. and some others. Over much of the range In body size the snakes studied are 15 rows are the normal number, but 17 near the minimum for the species. Popu- is the normal number in some western lations in the northeastern states, the far populations in which body size is large. West, and especially those in Utah and In some other western populations which Arizona, are much larger, up to about are notably slender-bodied, scale rows twice the linear dimensions of the Kan- vary from 15 to 13. In the population sas snakes. In some regions, especially studied, there is normally a neck ring at the far western states, the snakes are least 1/2 scale rows wide, but in eastern more slender than those from Kansas, and some far western populations the which appear relatively short and ring is narrower and /or broken on the stubby. The dark dorsal color is slaty in middorsal line, and in southwestern pop- some populations but may be suffused ulations it is absent. In the Kansas with brown, green or blue. In some snakes the red or orange ventral color is populations the ventral color is best de- confined to the ventrals and subcaudals, scribed as yellow, with relatively little but in most more western populations the ventral coloration encroaches onto the dorsal scale rows and may cover the first two on each side. The Kansas snakes have seven pairs of supralabials but some other populations have eight. In the Kansas snakes the black marks of the ventral surface tend to be irregular but in the southeastern populations the mark- ings are regular and symmetrical with a half-moon shaped central spot on each E ventral scale, and in some far western E populations the ventral markings are normally absent. The number of ventrals in Diadophis punctatus arniji ranges from 142 to 185, and, for the species as a whole, from 126 to 239 (Wright and Wright, 1957:159). The numbers of ventrals in females ex- ceed the numbers in males by from 10 to 20 in different populations. In general, far western populations have more ven- trals than D. p. arniji and eastern popu- lations have fewer. The subcaudals num- ber from 30 to 79 and there are usually 6 to 8 more in males than in females within any population. HABITAT Fig. 4—Above, hemipenis of Diadophis punc- As a transcontinental species Dia- tatus; below, lateral view of left maxillary of occurs in most of the Diadophis punctatus. dophis punctatus 12 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY

with major biomes of North America. In the situations, especially south-facing and little region of my study it occurs in a variety an open canopy underbrush, soil and of habitats but is especially associated are favorable, whereas soggy with the ecotone between deciduous for- deep shade under unbroken leaf canopy are unfavorable. but est and prairie. Under original condi- (4) Prairie, gener- tions the transition from forest to prairie ally in association with such features as rock and of was sharp and clearly defined. Under gullies, outcrops patches of modern conditions woodlots, groves, old brush, indicating that extensive areas are little fields and pastures provide a spectrum level, homogeneous grassland of combinations of the two main types of used. (5) Riparian situations along the intermittent streams or artificial vegetation with habitats that are favor- edges of able for the snakes. ponds. Especially in dry weather mois- ture renders these situations Ringneck snakes are present on all attractive, and eroded banks, tree roots, parts of the Natural History Reservation. exposed and accumulations of drift However, this area, having a variety of rocks, provide Old but topographic features, past treatments, hiding places. (6) fields, only after dense has be- and plant associations, is unequally used ground vegetation come established, shelter. by them (Figs. 5, 6). The transition providing In the snakes are not lim- from low to high numbers reveals the summary ited to one but occur in combination of ecological factors re- any habitat, various of terrain and quired by the species. There is some types vegetation. chief are soil seasonal shift between habitats, and in Some of the requirements some situations where the snakes use that is slightly damp but not wet or abundant shelter in the form of a loose surface objects for shelter, they are soggy, surface mat of dead and /or more readily found than where such vegetation loose such as flat boards or shelters are lacking, even though the lat- objects rocks, trees with ter situations may have more snakes. trash, and screening shrubs or leaf to Subject to these constraints, habitats rep- canopies sparse enough permit resented on the Reservation have been abundant sunshine to reach the ground. found to have in ringneck snakes, ap- BEHAVIOR proximately the following order of abun- dance : 1 Old domi- snakes are ( ) hilltop pastures Undisturbed ringneck nated by Bromiis inennis, with thickets, rarely seen despite their great abun- clumps and scattered small trees of Cor- dance, because they tend to keep under nus drummondii, Mains ioensis, Madura cover. However, over the 26-year span pomifera, Gleditsia triacanthos, Ulmtis of my observations at the Reservation, americanus and others. Bottomland pas- many have been found on a county road tures with similar plant assemblages are that crosses the area or on the driveway slightly less favorable habitat for the between the county road and residence are snakes, perhaps because they on the (.5 km). Such a snake, when first seen, average cooler and damper than the hill- was usually motionless and would re- tops. (2) Hilltop edges with limestone main so even when closely approached outcrops and with loose rock strewn over by a person on foot, or when an auto- adjacent upper slopes, and with brush mobile passed over it. However, after a and intervening open spaces. South- pause, especially if actually touched, it facing hilltops that are relatively open would make violent wriggling move- and have an abundance of flat rocks are ments to gain a place of concealment. preferred over those that face north or In a highly excited individual there was are heavily shaded with trees or brush, sometimes a lateral lashing of the tail as lack loose ground objects providing hid- the snake crawled. In all instances the or were ing places. (3) Woodland; well-drained snakes on the road driveway FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 13

Fig. 5.—Upper, summer habitat of high population of Diadophis in "House Field," with dense, low vegetation, scattered trees and brush, July 1974. Lower, nursery area, with sunny, open slope, loose rock, and deep crevices from former blasting, at abandoned quarry where many females congregated for egg-laying; July 1974. 14 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY

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l^'iG. 6.—Upper, liibeniation area at abandoned quarry, with sunny, rock-strewn slope and fissured limestone outcrop in background; metal strip in foregroimd was attractive to snakes when warmed by sunshine in cool weather; November, 1973. Lower, "Quarry Field," providing optimum summer habitat for the snakes, with dense herbaceous vege- tation, interspersed with trees and clinups of brush. FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 15 found by day, sometimes in bright sun- and body, show no spiralling response, that liglit, leading to the conclusion they or have it only feebly developed. Those are mainly diurnal; but, because of small populations that have yellow pigmenta- size and dark coloration, they would not tion of the body grading into bright at coral have been readily detected night. red on the tail have the spiralling Ernst 1962 observed nocturnal well ( ) activity response developed. My own ex- in Maryland. perience has been mostly with Diadophis Behavioral thermoregulation usually punctatus arnyi of northeastern Kansas, involves contacting sunshine-warmed ob- in which the display is relatively well jects rather than exposure to direct sun- developed, but my limited experience light. The snakes use flat rocks, and in with the subspecies amahilis and occi- altered habitats use boards and metal dentalis in California and Oregon has strips. In a horizontal flat coil, the snake indicated that in these the response is has its dorsal surface in contact with the stronger and more easily triggered than undersurface of the shelter, and may be in the Kansas snakes. warmed to above ambient air temper- At the Reservation in October, 1973, ature. When is suffi- body temperature one hundred recently captured ringneck the snake withdraws from ciently raised, snakes were tested in the laboratory for contact with the and sheltering object tail spiralling response. Each in turn was nestles in a retreats into a depression, grasped at mid-body with metal tongs, hole or crevice, or leaves the vicinity. removed from the container where it The combination of a dark, almost had been burrowing in decaying wood, uniform, somberly colored dorsal surface and released in a large enamel pan. and a brightly colored ventrum com- Grasping the snakes and releasing them bines the advantage of cryptic coloration in an open place excited them and often with the capacity for flashing a startling evoked spiralling, but if the response did display, or making a show of sematic not occur after about five seconds, the colors. Musk with semi-liquid feces and snake was tapped on the tip of the snout uric acid is voided by a snake that is as further inducement. If the spiralling captured, frightened or injured. A snake still did not occur after several taps, the struggling to escape writhes vigorously, snake was held down against the sub- smearing its captor and its own body strate. If the spiralling did not occur with malodorous voided substances. Si- even after several seconds of such re- multaneously it coils the tail in a tight straint, a final stimulus was applied in spiral, elevated so that the coral red the form of a light pinch on the rear of undersurface is conspicuously displayed the body with sharp-pointed forceps. (Figs. 7, 8). When released 12 of the snakes coiled Many genera of snakes, both venom- their tails with no further stimulus (in ous and non-venomous, have tail displays four of these the coil was loose, forming (Greene, 1973) that may serve to warn a loop rather than a spiral). Two more natural enemies of venomous or distaste- coiled their tails when tapped; 46 others ful qualities. However, tail-spiralling is did so when held down, but in six of peculiar to Diadophis. The display varies them the tail was merely looped, and in in the position of the tail, the number of 12 others the spiral was imperfect or coils in the spiral, and the kind and de- loose. Fourteen coiled their tails when gree of stimulation required. Myers (1965) pinched (eight of these formed a loop). has shown that the response varies geo- The remaining 26 snakes did not coil graphically, and that it is correlated with their tails in response to any of the intensity of ventral coloring. Those pop- stimuli. However, responses were un- ulations in which the ventral surface is doubtedly conditioned somewhat by all yellow, with no contrast between tail handling of the snakes in the field at the 16 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY

Fig. 7.—Upper, adult female ringneck snake and one of her brood of four, illustrating relatively large size of hatchlings; August 1974. Middle, adult female and her clutch of four eggs; July 1974. Lower, clutch of three eggs, one normal (left), one unusually elongate (liehind), and one with right angle bend, July 1974. FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 17

Fig. 8.—Upper, adult female ringneck snake after capture, coiling tail and exposing brightly-colored undersurface in "warning" display. Lower, adult male after handling and release, with tail elevated and coiled in tight spiral displaying bright ventral colors. Photo by Joseph T. Collins. 18 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY time of capture, and by repeated stimuli each other, with cannibalism sometimes from contact with other snakes when ensuing. Possibly this is the sole basis many were in the same container. for the observed attacks. In April 1974, 100 more snakes were tested in the field when they were first TEMPERATURE RELATIONSHIPS uncovered, holding each down mo- by Compared with most other reptiles of and its mentarily noting responses. northeastern Kansas, the ringneck snake Ninety-five their tails, another spiralled has a relatively long season of activity, held its tail in a and four loop, only averaging about 213 days and excluding failed to show tail The any coiling. only that part of the year in which snakes tested were a random presumably freezing regularly occurs. Behavorial and half were adult sample nearly (48) thermoregulation allows it to maintain a males. However, the spiralling response body temperature more nearly optimum seems to be well in equally developed than ambient temperatures. Small size adults and in first and in year young, and slender habitus pemiit rapid adjust- both sexes. ment of temperature with little effort on Tail spiralling is likely to have the part of the snake. evolved as a defense against diurnal The snakes occasionally bask in direct predators having color vision (especially sunlight, but usually remain concealed birds), and the musk is sufficient deter- and elevate body temperatures by con- rent to reinforce the display. It may be tact with sun-warmed objects, such as that in of speculated parts the geographic flat rocks, logs, strips of bark, leaf litter, range where tail spiralling is not de- and mats of dead herbaceous vegetation. other veloped, kinds of predators that Artificial objects, including boards, are or color nocturnal, lack vision, or are scraps of sheet metal, plastic or tarpaper, not deterred by the musk, are most im- are often preferred. The snake lies with portant. its dorsal surface in contact with the

Although trailing by olfaction is a overlying object. prominent aspect of the behavior, and Body temperatures averaged 26.1° ringneck snakes tend to aggregate, social (11.7= to 34.4°) for 129 snakes found relationships are primitive, and associ- beneath surface objects. In 109 instances ations between individuals are ephem- body temperature exceeded air temper- eral. As in most other snakes, there is ature and the difference ranged from zero to 13.6°. no territoriality, and aggressive behavior Only nine per cent of the is rare in intraspecific interactions. How- snakes (11) had body temperatures that ever, when many individuals are depos- were lower than nearby air temperatures. ited in the same collecting sack, attacks For 37 snakes found in the open, body may occur. In a group of several dozen temperature averaged 26.6° ± .62 (18.2° that have been bagged together, there to 33.3°). Air temperatures ranged from 16.2° to may be several interlocking pairs, either 30.0° at the times these snakes young or adults and of either sex. In my were found, and for the entire group experience the contestants are always of body temperature averaged 3.7° above approximately equal size. The upper in- air temperature. Only four of the 37 dividual has the face and muzzle of the were cooler than the air. lower one in its mouth, while the lower When air temperature approaches or one holds the lower jaw of its opponent, exceeds their preferendum, the snakes and because of the sharp, recurved teeth, tend to stay under shelter, but when air the snakes are not readily disengaged. temperature is relatively low, the oppor- Anderson (1965) stated that the odor of tunity to bask in sunshine provides in- disgorged earthworms smeared on the centive for them to move into the open. snakes' bodies caused them to attack For instance on 20 April 1955, when air FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 19 20 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY

Probably some individuals remain in mean dates for various events in the the areas where they have been active annual cycle and mean sizes (length and hibernate in such shelters as are S-V) of first-year young. The subse- available there, including the tunnels of quent rows are for specific years and voles (Microtus), moles (Scaloptis) and show deviations in days from the mean probably cicada nymphs (Tihicen, Magi- date, or deviation in millimeters from cicada). Others make trips of hundreds the mean length. of meters to hilltop rock outcrops where there are deep crevices that provide ASSOCIATED ANIMALS more secure hibernacula. Emergence On the Reservation and nearby areas from hibernation in occurs over spring in northeastern Kansas many species of several weeks and is controlled tem- by animals are associated with the ringneck that not on perature depends only snake, and elsewhere in its geographic weather but on the location and depth ranee the snake interacts with other, of the hibernaculum. Fall retirement quite different communities. In the area into hibernation also several weeks spans of my study, earthworms were the ani- for the as a whole, population judging mals most important in its ecology, from the numbers of snakes dwindling providing its main food source. Allolo- found active in late October and early hophora caJiginosa is much more impor- November. tant than all other kinds combined, in Adult males seem to emerge some- terms both of the frequency with which what earlier than females; anyhow they Diadophis interacts with it and the bio- at first. There arc much more in evidence mass of food that it provides. This is a is a shift from rock outcrops to more medium-sized, stubby-bodied, tan-col- open situations during April, and some ored earthworm that is native in Europe of occurs as indi- shuffling populations (Dr. W. Murchie, pers. comm.) and in- viduals that have hibernated together troduced into North America, where it is individuals from scatter and mingle with now widespread and abundant, occur- remote hibernation sites. relatively ring in various habitats. It is especially Ovarian follicles, minute at the time of abundant in damp soil under flat rocks emergence from hibernation, enlarge in open woodland or woodland edge in rapidly in early May, and ovulation takes the same sorts of situations that are fa- place in late May or June. Sloughing vored by the snakes. occurs in most of the population in late Other associated animals may be April or early May. Beginning in early grouped roughly into those that affect May the snakes become increasingly se- the ringneck snake indirectly by exten- cretive and subterranean, and by mid- sive alteration of the general habitat, are found. are summer they rarely Egglay- tliose that prey upon it, those that occurs in late or and that ing June early July, potential competitors for food, those or hatching in the last week of August themselves are potential food sources, in September. Also in September a com- and those that are essentially neutral in bination of cooling weather and heavy the ecology of the snake. In the first rains cause the snakes to reappear in category are livestock (mainly cattle) abundance in superficial situations where and deer, which alter the vegetation and they have not been in evidence since soil by their feeding, trampling and spring. In late September and October droppings. They may often kill snakes there are population shifts back to the by accidental trampling. Also, they may vicinity of hibernacula. improve the habitat by removing dense Table 3 shows an incomplete phe- vegetation and creating open areas nology for ringneck snakes on the Reser- where the snakes have more opportunity vation. The first tabular row shows both to bask. Areas that are subjected to FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 21

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CO M i-l CQ < 22 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY medium or heavy grazing support higher All of these are much more specialized population densities of the snakes than than Diadophis in their habitat require- do ungrazed areas that are otherwise ments, but overlap Diadophis. None comparable. Small animals that dig ex- approaches the high population densities tensive burrow systems also alter the attained by Diadophis, which is usually habitat by rendering it more favorable the dominant kind even where it occurs for the snakes, which spend much time in association with one or more of the underground yet lack capacity for dig- others. ging. The mole Scalopus aquaticus, Tantilla gracilis and Virginia valeriae chiefly in woodland, and the vole Mi- are remarkably small snakes; young or crotiis ochrogaster, chiefly in grassland, even adults are potential prey for Dia- provide an abundance of tunnels that dophis. In Arizona Tantilla icilcoxi has arc used by the snakes. The mole is the been recorded in the food of Diadophis more persistent burrower, but its bur- (Van Denburgh, 1922:654). A hatch- rows ordinarily are not open until bro- ling Ophisaurtis attenuatus is the only ken into by larger animals or by running lizard recorded in the prey on the Reser- water. The main tunnel systems of both vation, but hatchling skinks (Eiimeces these mammals are horizontal and some- fasciatus and Leiolopisma laterale) are a what less than 10 cm beneath the sur- potential food source, as are newly meta- face. Burrows of the pocket gopher morphosed anurans Acris crepitans, Geomys bursarius, pine vole Microtus Pseudacris triseriata, Bufo americanus, pinetorum, and bog lemming Sijnaptomtjs and Gastrophryne olivacea. cooperi may also be used. Much more available shelters are the cylindrical, ver- FOOD HABITS tical tubes of cicada emergence nymphs In my study, made near the center of (Tibicen pruinosa, Magicicada septen- the species' geographic range, the trend M. cassini and The tun- decim, others). of the food habits differed notably from nels are somewhat more than 1 usually the trend indicated by published litera- cm in diameter, for the large enough ture, or by any single published account. snakes to move and turn in, and provide Significant geographic variation in food convenient retreats to where depths is evident, and seems to be correlated moderate and humid- temperature high with parallel changes in size, bodily pro- the tunnels of the ity prevail. Ordinarily portions, habitat and behavioral traits. Tibicen are most but in larger available, Ernst (1962:266), in a brief popular the of such emergence years Magicicada, account based mainly on observations in as 1947 and the soil is riddled with 1964, Maryland, wrote that earthworms, small tunnels and the of shelters availability salamanders (especially Plethodon cine- is increased, for tremendously especially reus), slugs, giiibs, newborn snakes, small individuals of Diadophis. toads, frogs and various insects were Known and suspected predators on eaten. He stated, "I have observed ring- the snakes are mentioned in the section necks capturing winged insects that have on predation. Of these predators, the fluttered to the ground after being at- mole the and two species of shrew also tracted to a night light." Myers (1965: feed to a large extent on earthworms 63) obtained stomach contents of 74 of and are potential competitors of Dia- the snakes from Alachua County, Flor- dophis. Other earthworm-feeders that ida; 26 had earthworms, one contained a might compete with Diadophis are salamander (Manculus quadridigitattis), mostly small snakes including Carpho- four contained narrow-mouthed frogs phis vermis, Thamnophis sirtalis (espe- (Gastrophryne carolinensis), two had ju- cially first-year young), Storeria dekayi, venile frogs (Rana pipiens) and another Virginia valeriae and Tantilla gracilis. contained an unidentified frog, two con- FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 23 tained ground skinks (Leiolopisma lat- regalis of the arid Southwest and arriyi erale), and one contained unidentified of the central states. In discussing their reptile scales. Myers also recorded a food habits Wright and Wright cited the salamander, Eurycea bislineata, from the publications of 28 earlier authors. In stomach of a ringneck snake from Leon most instances the food records for each County, Florida. In northern Michigan, kind of ringneck snake were obtained by Blanchard, Gilreath and Blanchard (in a different group of authors. Of the nine press) found from the combined evi- subspecies figuring in the records, seven dence of food disgorged by captured were reported to have eaten insects, snakes, and from experimental offering seven had eaten snakes, five each had of possible prey species to those in con- eaten lizards, salamanders, frogs and finement, that the salamander Plethodon earthworms, two had eaten toads and cinereus was preferred and was preyed one had eaten slugs. The subspecies upon much more often than any other arnyi, which includes the population on is had eaten species, although earthworms and hatch- which my own study based, ling snakes were also taken. prey of all these categories, excepting At Big Black Mountain in eastern slugs. Kentucky, Barbour (1950:104) obtained In summary the literature records a sample of ringneck snakes (Diadophis indicate that Diadophis punctatus is 18 punctatus edwardsi) and dissected 53, euryphagous; its known food includes It consisted of which contained prey. diverse types of small terrestrial animals the Plethodon chiefly of salamanders, of four phyla. Therefore, it is remark- glutinosus, Desmognathus fuscits (both able that a sample from the Reservation, adults bislineata and larvae), Eurycea much larger than any assembled else- and Aneides aeneus (eggs). However, where, indicates feeding almost entirely 11.1% in wood roaches were frequency limited to one kind of prey. Stomach and 7.5% in volume. Other insect frag- contents were palped from each of 182 ments and miscellaneous debris were in- snakes captured on the Reservation in of the terpreted as stomach contents 14 different years from 1951 to 1974. salamanders. The 224 items included 221 earthworms, Gehlbach (1974:144) stated that in two tipulid larvae and one hatchling Texas ringneck snakes (both D. p. arnyi glass lizard (Ophisaurus attenuatus). identified and D. p. regalis) feed mainly on small Many of the earthworms were reptiles. In laboratory tests he found as Allolohophora caliginosa, and prob- that they would catch and hold small ably most were of this species. snakes such as Virginia and Sonora and A total of 347 fecal droppings were would chew or cling to the site of the collected from the ringneck snakes sometimes for several original bite, hours, processed in 1959, 1960 and 1961, and until the prey was immobilized, seem- were examined under a dissecting micro- killed or the toxic ingly paralyzed by scope. In 56 of these "scats" there was saliva, conducted into the wound by the nothing identifiable, but in each instance enlarged posterior maxillary teeth. the material seemed to consist mainly or Most earlier literature was summa- entirely of soil which might have been rized by Wright and Wright (1957) who residual from the digestive tracts of discussed food habits separately for each earthworms after the soft parts had been hard of nine kinds of Diadophis currently dissolved. In 291 scats some parts a clue considered conspecific, but recognized as of the prey remained, providing contained setae valid subspecies. They are amahilis, to its identity; 288 only modestus, occidetitalis and similis of the of earthworms, three contained frag- West Coast, edwardsi and punctatus of ments of chitin as residue from insect setae and the eastern United States, laetus and prey, and two contained both 24 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY chitin fragments. Traces of plant mate- of feeding experiments using snakes from rial occurred in 177 scats. Some of this the same population that I studied. vegetation was still green but most of it Starting with snakes that had empty di- was old and decayed; it might have gestive tracts, he found that the first come from the guts of earthworms, or defecation occurred in as little as seven might have been ingested accidentally hours after feeding in snakes maintained as the snake swallowed prey. near their maximum temperature toler- Miscellaneous materials found in ance, at 35°, and that first defecation scats included masses of nondescript soft ordinarily occurred in from 15 to 30 tissue (probably from earthworms in hours in snakes kept at 24° to 33.° Di- most instances), crystals of uric acid, gestion can occur even at low temper- teeth of the snakes themselves, soil par- atures; in one snake kept at 7° defecation ticles, and (in two instances) fine hairs occurred after 312 hours. Henderson or hairlike fibers. found that after an earthworm meal Each of 170 snakes checked for stom- there were from two to six (average 4.2) ach contents contained one earthworm successive defecations, with four occur- and nine snakes each contained two ring most frequently. At 33° last defe- cation occurred two or three earthworms. Probably in many instances only days after and at 25° it occurred in the food that happened to be in the ingestion, stomach was undetected when the snake four or five days. was processed. The elongate shape of Combined evidence of Henderson's an earthworm usually caused no discern- study and my own field data suggest that ible bulge in the body of the snake. The the average ringneck snake feeds about part of the prey in the posterior end of once every eight days, that about half the snake's stomach disintegrated first, the interval is required to digest and and palpation did not readily reveal assimilate the meal, and that the snake presence of the object. In April 1973 has an empty digestive tract for the re- special effort was made to detect food in maining half. At this rate of feeding a the stomach or fecal material in the hind snake would take about 27 meals, ingest- gut. Of 83 snakes processed on 6, 11, 12, ing approximately three times its body 13, 17 and 18 April, 34 produced scats weight, in a normal growing season esti- when the rear end of the body was mated at 213 days. palped and 17 had stomach contents; 9 of these snakes yielded both stomach SPATIAL RELATIONSHIPS contents and scats. Thus 42 of the 83 In the course of routine field work, snakes had food or food residue in the numerous snakes captured for processing tract. digestive were generally deposited in the same In 70 instances in which both the container without noting the precise cap- snake and its earthworm prey were ture points. For these, distances trav- measured, the worm averaged 34.1 ± elled between captures were usually not 1.58% (14 to 97) of the snake's length known, but, as recapture records accu- (S-V). In 45 instances in which the in- mulated, it became evident that each tact earthworm was weighed, it averaged snake had usually stayed within the 11.9 ± 0.87% of the snake's weight. same small study area such as the quarry, Such relatively small prey might be ex- Quarry Field or House Field. Likelihood pected from the minute head, delicate of recapture was greater in those that jaws, and attenuate body of the snake. stayed in the study areas than in those Frequency of feeding is no doubt greater that wandered away from them, but in these snakes than in those which in- spacing of the study areas was well gest relatively bulky prey. adapted to show relatively long move- one Henderson (1970) performed a series ments, when a snake shifted from FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 25

were the sum- study area to another, and such shifts ably where they spending were recorded occasionally. mer) were examined. Fifty such move- Some of the capture records that ments averaged 121 m and half of them were obtained involved precise stations were in the range 67 to 174 m. Many such as those occupied by funnel traps other snakes, caught in early April or at the ends of the drift fences, and pieces late September, were probably near their of sheet metal put out to attract the hibernacula and their relatively long snakes. When two or more of the cap- movements between these sites and their ture records for any individual involved summer ranges raise the average some- such definite field stations, the distances what. between them could be readily measured Figure 11 shows the recorded move- on the map. In all, 433 such measure- ments grouped in 10 m intervals. It ments were obtained and these averaged shows that nearly one fourth of the 80 m (0 to 1700). In 86 instances the movements were distances less than 10 distance was recorded as zero, but the m and one third more were between 10 actual capture points may have been as and 70 m and 22 per cent were between much as several meters apart. Table 4 70 and 140 m, with the remainder longer shows the trend toward greater distances distances up to 1700 m. The histogram with elapsed time. In general, the longer reveals a trend toward progressively the time, the farther the snake would be fewer records for longer distances. There from any given starting point. However, seem to be rather abrupt reductions be- each snake tends to revisit certain points yond distances of 10 m, 70 m and 140 m, into from time to time, and to turn back respectively, and these steps may have a known area instead of wandering in- biological significance. The much larger definitely. number of records between and 10 m The 433 distances measured include than in any other 10 m interval, espe- indicates attachment to small several types of movements such as day- cially, of these to-day foraging for food, gradual or areas. The significance many in abrupt shift from one favored area to short movements is believed to be, of the another, and regular seasonal migrations part, the slow rate of travel snakes, involving travel to and from hibernacula so that one recaptured after several days, or but in most cases egg-laying sites, or perhaps even after several weeks, these cannot be In order distinguished. often would still be lingering in the vi- to determine the usual distance of travel without cinity of its previous capture, between hibernacula and summer ranges, having covered much of its actual range. the records of individuals captured in Also, habitual return to a favorite spot March or October (presumably near the within the home range, even after long place where hibernation had occurred or must have been involved. In would occur) and caught also between intervals, instances a snake was late April and mid-September (presum- many recaptured

Snakes in Various Table 4.—Distances Travelled by Marked and Recaptured Ringneck Time Intervals. 26 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY

100 200 300 DISTANCE OF MOVEMENT: METERS

Fig. 11.—Distances moved by individual ringneck snakes between captures. at approximately the same place after a ing to the sex and age of the individual. year or more. Undoubtedly such differences exist in Movements up to 70 m are numerous Diadophis also. However, the sample and their numbers are near the same in obtained was heavily weighted to adult each 10-meter interval. These probably males (58 per cent) with relatively few represent normal movements within a adult females (11%) and first-year young home range and suggest that a nomial (both sexes combined 17%) and even home range may have a diameter of fewer second-year young (both sexes approximately 70 m. Between 70 and combined 14%). Average distances were 140 m, records are less numerous than 44.4 m for first-year young, 55.0 m for they are for shorter distances and tend adult males and 102.1 m for adult fe- to decrease gradually; beyond 140 m males. The proportion recaptured at the there is an abrupt decrease. It is sug- original location differed significantly: gested that the many recorded distances 43.8% in first-year young, 17.7% in adult between 70 and 140 m were mostly males and 11.7% in adult females. within the of the individ- home ranges The finding that first-year young are uals concerned, and that they reflect un- much less vagile than adults is in line usually large or elongate ranges. The with what is known about other snakes, 140 relatively few distances exceeding m and animals in general. It was surprising are probably outside the snakes' normal to find that adult females averaged ranges and represent shifts or extensions nearly twice as much distance as adult of or small original home range, perhaps males, and were relatively seldom re- scale migrations between summer ranges captured at an original capture site. and hibernacula or egg-laying sites. Probably their greater vagility is corre- In other kinds of snakes it has been lated with their larger size, and with the found that the kind and amount of travel fact that at least some of them travel to and size of range differs greatly accord- and from special nesting areas. FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 27

REPRODUCTION ture and handling and unnatural sur- roundings, and has never been observed punctatus is oviparous and Diadophis in the many ringneck snakes kept in its is on an annual cycle. reproduction confinement at all times of year. Even are minute at the time Ovarian follicles under natural conditions sexual behavior of from hibernation, they en- emergence has rarely been observed, and this is re- in late ovulation large rapidly spring, markable in view of the great abundance occurs in and occurs in June egg-laying of the snakes. Active courtship was ob- or Incubation is late June early July. served on 24 September 1959 at 4 P.M. in and and hatch- mainly July August The female involved was in process of near the end of lings usually appear sloughing and was crawling slowly or in August September. through the surface litter in open wood- and — Aggregation Mating. Trailing land, partly exposed. The slough had by olfaction brings the sexes together peeled back for about half the length of and increases opportunity for mating. her body. A male was beside her, facing showed that Dundee and Miller (1968) in the opposite direction. For several the small aggregations of ringneck snakes minutes that the snakes were watched, ob- frequently found under sheltering the male alternately lay passive or made in result from of jects spring following jerky, animated courtship movements, the scent trail left by contact of the skin obviously stimulated by scent emanating with the substrate. When one individual from the moist, newly-exposed skin. The has found a shelter, others may follow it snakes moved out of sight beneath leaf there. Aggregations are most prominent litter, and when it seemed that they in spring when surface activity is at its would not reappear, leaves were gently peak, but are evident also in fall. Al- brushed aside exposing the pair to view. thouo;h the snakes are seldom seen in Meanwhile another male had joined summer, they probably aggregate then, them and both males pressed against the but in deeper and better insulated shel- female but the anterior ends of all three ters than are used in spring and fall. The snakes were concealed. Posterior ends females at least in some instances use of the two males were momentarily in- communal egg-laying sites. tertwined and were apart from the fe- evident be- The aggregations found in spring in- male. There was no rivalry clude both adults and immatures, males tween the males as each pursued its re- and females. There is some tendency for courtship, but confusion and delay from the of the extra the first-year young to aggregate with sulted presence moved out others of their size segregated from male. Soon the snakes again not be relocated. adults. However, in general adult males of sight and could make up a high proportion of the indi- Copulation was observed at approxi- viduals in aggregations, which probably mately 5 P.M. on 7 May 1974. The pair form partly as a result of sexual search. of snakes was found in damp soil be- did Skin odors are the basis for trailing neath a heavy decaying plank. They of (Noble and Clausen, 1936; Dundee and not separate when exposed by turning nor for about 20 minutes sub- Miller, 1968) but it is not clear how the plank were under much discrimination is exercised by the sequently that they kept observation. The female was nervous trailing individual in distinguishing sex out her al- and reproductive condition of the one and active, darting tongue fre- being followed. Musk from the scent most continually, shifting position a short glands is secreted only when the snake quently, and sometimes crawling the is frightened or injured, and its odor in- distance, dragging relatively passive her. From time to time the hibits trailing. male after coiled in a com- Sexual behavior is inhibited by cap- snakes together fairly

I 28 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY

mass, the male often his ber = 63 and 2.5 cent in pact pressing ( N ) , per Octo- snout against the female's side. After a ber (N = 80). few minutes' in the gap observations, the On 1 May 1966 seven large females, snakes were found to have disappeared all negative for cloacal sperm, were dis- and could not be relocated. sected. All but one had quantities of Reproductive Cycles.—In four differ- active sperm in the oviducts. Ovarian ent years on dates representative of the follicles were only beginning to enlarge 6.0 to entire season of activity, a total of 484 (largest 8.5 mm, much short of the adult males were tested for motile sperm size at ovulation which is usually 25 mm by gently palpating the rear of the ab- or more). On 24 April 1955, six females domen to eject renal and fecal wastes, were dissected and they contained an then pipetting a drop of physiological average of 6.5 small ovarian follicles saline into the cloaca. By gentle back- ranging from 1 to 6 mm in length but with ward massaging of the posterior part of a distinct bimodality in size. The the abdomen, semen was pressed from larger, clustered about a length of 5 mm, the vas deferens into the cloaca, and were probably destined for ovulation in into the droplet of saline solution, which the current season, while the smaller was expressed from the anus onto a glass clustered about a length of 1 mm, prob- slide and examined. Active sperm were ably would have been retained until the found in 98.0 cent in per April ( N = following year. 204), 95.4 per cent in May {N = 65), In May follicles enlarge rapidly and 91.0 per cent in September (N := 165), ovulation occurs in June. In eight differ- ent and 93.4 per cent in October (N = 30). years 86 females captured in June, Of 19 males tested in June, July and their bodies distended with eggs, were August, only one lacked motile sperm. held in confinement until deposition of Negative results did not necessarily indi- their clutches. Average egg-laying date cate that were for this was 3 ± .87 sperm absent; they may group July ( day ) , have been overlooked. The tests indicate but dates extended from 19 June to 24 that most adult males have motile sperm July with a standard deviation of 7.25 throughout the year and that insemina- days. Much of this variance resulted tion might occur at almost any time, from the difference between years; egg- providing males have sexual drive and laying and other phenological events in females are receptive. the annual cycle of the local population be accelerated or retarded In adult females sperm can survive may by un- mild weather or cold weather for relatively long periods in vascular- seasonably at critical times in ized pouches of the oviducts, but prob- spring. ably their maximum survival in the clo- On 6 August 1965 a female of 319 aca is only a few days at most. In a few mm (S-V) was found to have three instances tests revealed massive clumps shelled eggs in her oviducts and the eggs of sperm, but more often the numbers contained living embryos larger (3.3 mm) than those found in laid were small, and at all times of year the usually freshly eggs. This date, 34 days later than the majority of females tested were negative. indicates a The 625 females tested had the follow- average oviposition, spread of more than six weeks in egg-laying and ing percentages with active sperm in explains the presence of hatchling sized different months of the season of activ- snakes in late spring when most have in March = 5.8 cent ity: (N 28), per grown well beyond this minimum size. in April (Nr=197), 20.2 cent in per Peterson (1956:152) noted a remark- May (N= 178), 16.4 per cent in June able instance in which a female Dia- = in = in Au- {N 61), July (N 30), cJophis punctatus stictogenys from the gust (N = 16), 7.9 per cent in Septem- Miami area of southern Florida gave FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 29 birth to a litter of six living young. In ance, females kept in confinement in late this case the eggs were retained in the June and early July sometimes laid eggs female beyond the usual time of laying. that lacked shells and were inviable. In newly laid eggs of Diadophis the Often one or more such eggs were laid embryos are somewhat more advanced in a clutch along with normal eggs. The than are those of many other kinds of inviable eggs averaged slightly smaller, oviparous snakes. and are flaccid rather than firm. Clark Eggs.—The eggs are elongate and (1970) in his study of Carphophis also remarkably variable in shape (see Fig. found that confined females often pro- 7). Often they are nearly cylindrical, but duced unshelled eggs, and he concluded in some the ends tend to be pointed. In "Shell-deposition may be a crucial step some both ends are similar but in others in development, such that a gravid fe- one end is more enlarged. Typically the male collected and confined prior to shell eggs are somewhat curved, and sausage deposition generally reacts by laying her shaped. eggs in their premature condition." In In 251 eggs of 72 clutches, width Diadophis likewise, eggs that lack nor- varied from 21.7 to 46.8 per cent of mal shells are believed to result from of the fe- length. The length averaged 25.2 ± .277 handling and /or confinement mm (17 to 43). Width averaged 7.11 ± males at a critical stage in their egg .045 mm to (5.2 10.0). Weight averaged production. — .89 ± .001 grams (.58 to 1.35). Size of Clutch. For 300 clutches, The eggs are white, but the soft, thin mean was 3.89 ± .083, with a range of from shells are partly translucent so that the one to ten. Data were obtained in females dis- coloring of the yolk is faintly visible. unlaid eggs, either found The eggs are firm and turgid when laid sected, or palpated in live individuals, and as incubation proceeds they gradu- and from eggs laid by females isolated of the more im- ally absorb moisture from the surround- in confinement. Some size of the ing medium, and eventually they almost portant factors affecting of the fe- double their original weight. As liquid clutch are size (and/or age) is absorbed, the eggs become increas- male, the year, and the stage of develop- counts are since ingly turgid by stretching of the shell, ment at which made, are eliminated be- and the shape changes slightly, with apparently some eggs of ovluation and ovi- more increase in girth than in length. tween the time Besides the eggs of normal appear- position.

Table 5.—Number of Eggs per Clutch and Relative Productivity of Females of Different Year Classes.

Length (S-V) of Females MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY

34 -10

10

CO 39 24 CD UJ 50 34 4

65 ^ 15 28 cr -5 ' lij CD

3 I'

J- O. J. 250 300 350 SNOUT VENT LENGTH IN MILLIMETERS

Fig. 12.—Number of eggs per clutch in female ringneck snakes, showing relationship of clutch size to length of female. Mean, standard error, standard deviation and range are shown for each of the larger series.

Eggs laid averaged 3.36 ± .153 per class averaged higher (4.74) than those clutch (N = 50), whereas those palped in the 300-309 or 310-319 classes (4.33 or dissected 3.96 .096 as averaged ± ( N = and 4.65). Seemingly size, such, 267). These figures imply that 15 per rather than age determines productivity. cent of the are eliminated eggs between Table 6 shows mean numbers of eggs ovulation and oviposition. However, per clutch in different years, arranged in most of the records of laid were eggs order from the largest clutches (in 1963) obtained in 1965 when clutch size may to the smallest clutches (in 1965), along have smaller than in been other years. with weather factors that might be ex- In 53 unlaid clutches that were 1974, pected to affect fecundity. Amount and and 17 clutches palped averaged 3.81, distribution of precipitation affect avail- that were laid 3.47. All the averaged ability of earthworms, which provide females that oviposited in captivity had most of the food. Ova are minute when been palped two or three weeks earlier the snakes emerge from hibernation in and some loss have resulted. may March. Therefore, availability of food In Table 5 females are grouped on in the spring period of April, May and the basis of size according to most prob- the first half of June might be expected able age, and it is shown that the mean to control the development of eggs, and size of clutch increases from 2.37 in the availability of earthworms as food probable third-year individuals (produc- would depend on both the amount and ing first clutches) to 4.95 in those that distribution of moisture. In Table 6 the are probably seven years old or more. number of days having precipitation and In Figure 12 females arc further divided the amount of precipitation during the according to length with a 10 mm in- supposedly critical spring period and terval; a steady increase in size of clutch during the 11/2 months preceding the according to size of female is indicated, time of ovulation are shown. There is no except that females in the 290-299 mm evident correlation. In a study of Car- FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 31

Table 6.—Fecundity and Weather.

Mean Number of Eggs Per Clutch 32 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY

(S-V 275-294, N=12) and small (S-V year young) as follows: nesting area at 225-274, N = 2l) females. Clutch- east end of quarry (N ^ 40), hatchlings weight (as percentage of snake-weight) 78%; rocky upper slope near hibernacula differed as follows in these three groups: at "Tomb Rock" 165 m southwest of first large, 40.9 ± 1.10 per cent; medium, 39.1 location (N = 28), no hatchlings; ± 1.69 per cent; small, 38.1 ± 1.67 per "House Field" (N = 25), hatchhngs 16%. cent. These figures suggest that repro- The nesting area at the east end of ductive effort is greater in larger females the quarry was the best known one, and than in smaller, but the difference is it must have been used by dozens of relatively small. females from the adjacent field, judging Even with equal reproductive effort from the numbers of hatchlings found. the larger females produce more eggs The actual nests were not found, as than the smaller. Table 5 shows the search for them would have damaged quota of eggs calculated for each annual the habitat. Numerous potential nest age group. It shows that because of sites were provided by niches and deep shat- their relatively large numbers third year crevices in the limestone outcrop females produce the most eggs (one- tered by quarrying operations, with fifth of the total their more than 25 before, and ) , despite relatively blasting, years low individual productivity. Because of by the rock-strewn slope below it. A declining numbers, successively older second nesting area was near the middle 60 age groups produce slightly fewer eggs, of the old quarry, approximately m although individually the snakes become southwest of the first and perhaps not more productive. entirely distinct from it. Two other im- areas were known at Rat Nests.—Eggs were rarely found un- portant nesting der natural conditions, and most of those Ledge. observed were obtained from gravid fe- These nesting areas were all situated males held in confinement. However, on along hilltop outcrops of the Oread several occasions eggs were found in Limestone, in relatively open situations natural nests in damp soil beneath large, of southward exposure. Another nesting sunken flat rocks. At the Reservation area was in bottomland approximately headquarters on 3 August 1970, a com- 245 m west and a little south of the munal nest was found by workmen tear- Reservation headquarters, where the ing down a brick structure enclosing an driveway crossed a gully. An old and electric water pump. The brick wall was weathered stone check-dam, a cracked cracked and crumbling as a result of concrete slab, and a rock fill provided weathering; 15 eggs, probably represent- shelters with favorably moist nesting ing four clutches, were found in the sites, but there was some risk of flooding cracks. These eggs were partly incu- when the gully filled with run-off water bated and the females had left the area. after unusually heavy rains. Probably communal nesting is the Although hatchlings tend to be con- rule, judging from the fact that large centrated in preferred nesting areas, concentrations of hatchlings were found many others that seem to be recently year after year at certain favored spots. emerged are scattered in open habitats Such concentrations were found in Sep- where the adults spend most of their tember, October and even April; mean- time. Probably some of the females find while, hatchlings were relatively scarce nest sites without shifting from the areas in the areas where most adults were where they live. Abandoned burrows found. The 93 snakes obtained 1-15 such as those of prairie voles and cicadas April 1973 were from three locations, are abundant in the snakes' habitat, are each showing a characteristic biased ra- often used by the snakes, and on occa- tio of hatchlings to adults (and second- sion may serve for egg-laying sites. FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 33

GROWTH much undersized whereas others are

studied 1 much larger than the These Growth was by ( ) direct average. differences increase with time measurement of gains in length and elapsed and late some of weight of individuals marked and re- by spring the smallest are still of a size for hatch- captured, and (2) average differences in young typical whereas at the other extreme length and weight between series in dis- lings the of the in crete annual age groups. Both methods largest young year overlap size the smallest second are fallible and need to be used with year young. There- the consists caution, and in combination. fore, although population of discrete annual there is a The growth in marked individuals is age groups, continuum in size from the smallest to not typical of that in the entire popu- the individuals at lation because these small and delicate largest most times of year. Throughout the first of life snakes are adversely affected by routine year most young are as members processing and fail to grow normally for recognizable of their cohort. a small an indefinite period afterward. Of 55 Only percentage overlap in size those that are in their recaptured after one to ten days, seven second Second snakes are had gained weight and 48 had lost with year. year as such, but their a mean loss for the whole group of 5.44 usually recognizable size-range has increased and are per cent. In those recaptured after 11 to they overlapped in size both first- and 20 days five had gained weight and 17 by individuals. had lost with a mean loss for all of 5.36 third-year The course of per cent. In 21 to 30 days four of an- typical early growth is revealed best other group had gained weight and 13 by comparing mean size of series of from different had lost with mean loss of 11.1 per cent. young times of with the size of hatched Of 18 caught in spring and recaptured year newly individuals to determine the amount of in fall after intervals of 139 to 197 days, 12 had gained and six had lost with a gain in a given time. The course of later is revealed best mean average gain of 8.4 per cent. Each growth by the records of sample consisted of different individuals individuals marked and measured early in life and after intervals and all were fully adult so that growth recaptured that from the in length had stopped or greatly slowed. sufficiently long stunting From these records it can be concluded original handling had been overcome and was a minor factor. that the deleterious stunting effects con- relatively tinue to be severe as much as a month At the time of hatching the sexes are after handling, but that by four to six already somewhat different in size and months these effects have largely worn proportions; the females are larger with off. The direct cause of stunting is not shorter tails. As development proceeds, definitely known but perhaps handling the differences become more pro- and processing causes some shock, ag- nounced, with females attaining larger gravated by bruising or tearing of deli- average and maximum sizes. Therefore, cate tissues when the snake is grasped data for the sexes need to be separated. and stretched to full for firmly length In some years hatchlings are not found measurement, and results in a of period in substantial numbers until September fasting. or even October after the surface soil has In any one year most eggs are laid been moistened by heavy rain; probably within a few days in midsummer and the such individuals are already several hatchlings that emerge constitute a co- weeks old and have had time to hort which at first is readily distinguish- they still unassimi- able from older and larger young. How- grow, utilizing egg yolk at the time of ever, some of the hatchlings, although lated hatching, and then seemingly normal in most respects, are beginning to feed. Thus, the normal 34 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY

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l^ 0) CD -w (35 "55 —I o ti & in G 'X 05 O FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 35 hatchling size is best determined from ing late June, July, August and early young hatched in captivity. September. The second-year snakes have Young were hatched from 21 clutches increased by an average of 46.7% (males) in 1965/1967, 1969, 1970 and 1974; 50 or 49.8% (females) over the length of males averaged 109.3 di .91 mm and 33 first-year young at the time of their females averaged 114.1 ± 1.22 mm. Most emergence from hibernation. series of young collected in the field In Tables 7 and 8 some annual co- several cent than averaged per larger horts of young are definitely accelerated these laboratory hatched young, and pre- or retarded compared with others at the some sumably they had made growth same stages in their history. For exam- the time of and the between hatching ple, the young hatched in 1973 were time of capture. larger in April 1974 than the April young Tables 7 and 8 show mean lengths of other years. Development may be of young males and young females at delayed or hastened by early or late re- biweekly intervals for six different years, tirement into hibernation, but such early and for a composite of 11 earlier years differences tend to become smaller or when samples were generally smaller. disappear before the end of the first year. Each vertical column in the tables traces Another aspect of growth brought the growth of one cohort of young snakes out by Tables 7 and 8 is difference be- from the time of their appearance soon tween the sexes. In every sample of after hatching to an age of about 21 first-year snakes in which there were 20 months in late spring. The months of or more of each sex, the females aver- In the fe- July, August, and November through aged larger. 13 such series, early March are not included because males were 101.2 per cent to 104.7 per no samples of snakes were obtained then. cent of male length, with a combined Many other biweekly intervals in Sep- average of 102.9 per cent. In 11 corre- tember, October and March through sponding series of second-year young, 100.5 to 107.8 cent June of specific years lack data because the females were per no snakes were found, or samples were of male length, for an average of 104.2 inadequately small. Only samples of ten per cent. or more are included. Figure 14 is based on the snout-vent In some instances average length in lengths of first- and second-year young over the for No- a sample is slightly less than for a sample distributed year except of the same cohort in an earlier period. vember through early March, and July Such aberrations are due to chance and and August, when too few snakes were to the fact that successive samples in- found for an adequate sample. It shows volved different groups of individuals. that the females are consistently larger that make In most instances slight gain is indicated than males and young rapid first weeks. for each biweekly interval, but the aver- growth in their few How- age increment was small in cool weather ever, growth slows with the advent of in autumn. A just before hibernation and just after cooler weather high pro- are be- emergence. The following figures repre- portion of all first-year young in and sent average increments for the several tween 120 and 130 mm length, sexes are annual samples: late September to early the means for both usually from October, 3.63%; early October to late within this range August through until Those October, 1.32%; late March to early April, the autumn and spring May. in March and are 0.48%; early April to late April,' 2.08%; sampled early April smaller than those late April to early May, 2.16%; early May only slightly sampled From late to to late May, 2.72%; late May to early in early May. April early make June, 3.29%. Growth is fastest in sum- September young rapid growth, mer, but few snakes were obtained dur- increasing from about 130 mm to about 36 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY

180 mm; then, during their second au- longer interval. Since little growth oc- tumn, winter and spring gains are rela- curs from September through April, and since all the records are from tively slight. nearly An arbitrary dividing line between spring and fall, each record was assigned second- and third-year snakes is set be- to a particular age-class, with disregard tween 214 and 215 mm in males and for fractional years, although the actual between 223 and 224 mm in females, on age of those classed as two-year-olds, for the basis of the gains made by marked example, ranged from 24 months to individuals. Some snakes seem to suffer about 33 months. Also, the figure in- little or no stunting from the effects of cludes data from the series of unmarked that formed discrete classes processing, and most have overcome the young age effects within a month. Those recaptured at the time of hatching, and in the fall after the lapse of an entire growing and spring following hatching. The two- season or a longer interval were assumed year-old and three-year-old classes are to have made normal growth, the initial based upon recaptured individuals that stunting being a relatively minor factor. were marked as hatchlings. The remain- Figure 14, showing the growth curve ing age-classes are based partly on through the tenth year in females and those marked as hatchlings, but also on the eleventh year in males, is based upon those marked as second- and third-year the records of all marked individuals young and recaptured as adults. Because recaptured after a growing season or a second-year young overlap in size both

AGE IN YEARS Fig. 14.—Lengths of male and female ringneck snakes marked eady in life and recaptured. In each series mean, standard error, standard deviation, range, and sample size are shown. Growth is rapid in the first three years but is slow in the older snakes. Females average larger and plot above males. FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 37

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tr- 38 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY first-year and third-year young, there is already somewhat longer than males, at some uncertainty as to the age of any an age of 20 months they are five per individual marked when partly grown cent longer, as young adults at 32 months and recaptured as an adult. Each such they are nine per cent longer, and in old individual was arbitrarily assigned to the adults they are 15 per cent longer. Fig- age class most typical for snakes of its ure 15, showing average and individual size at the time of its first capture. The length increments in successive years figure shows that growth is most rapid after hatching, indicates that females just after hatching and in the growing grow faster. After the third year the season following the first hibernation, snakes gain weight relatively slowly. that in the second full growing season Actual length gains in millimeters aver- the rate has slowed to about two-thirds aged 54, 43, 23, 10, 2 and 4 for the first and in the third season to one-third, and six years in males, 63, 51, 19, 9, 7 and 3 that thereafter, as adults, the snakes for females. In the adult snakes the make only slight gains from year to year. usual annual growth is not much greater At the time of hatching females are than the expected margin of error in

o o

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LU

^9

8

7

6 cn < oro 5

4 X CD UJ 5 •3

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150 200 250 300 SNOUT VENT LENGTH IN MILLIMETERS

Fig. 16. —Relationship of length to weight in ringneck snakes, grouped in fi\'e-mil]imeter intervals. For each length interval sample the standard error, and standard deviation and range of weight are shown.

The 279 snakes caught on this occa- was the locale of intensive population sion represent a minimum popuhition of study for four years before the collection 73.5 per hectare. On numerous other and seven years afterward (including occasions from 1964 through 1974, the the 1968 season); therefore, much infor- same series of shelters (and others added mation is available about some of the subsequently) were turned in routine individual snakes caught. Of the 279 search but on no other occasion were so total, 156 were caught only once, on 13 many snakes found at one time. In eval- April 1968, never before or after. Fifty- uating the significance of the series of three others were caught one or more snakes to determination of population times before that date but not afterward; density, it is necessary to know whether 51 were recaptured subsequently but not individuals were residents or transients, before, and 19 were caught both before how large an area might be covered by and afterward. The snakes in this group individuals and to what extent the local tliat were caught on other occasions population was using the specific shel- were distributed by years as follows: 4 ters checked. This same 3.8-hectare field in 1964, 7 in 1965, 32 in 1966, 2'4 in 1967, FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 41

21 in 1968 (7 before 13 April and 14 In the spring of 1968 after 13 April, after that date), 27 in 1969, 20 in 1970, there was little opportunity for further 4 in 1971, 5 in 1972, 5 in 1973 and 4 in field work, but 23 snakes were captured 1974. The 279 snakes inchided 245 on 21 April and eight on 10 May and adults (203 males and 42 females), 24 these 31 included only one recapture 17 males and 7 fe- from the 279 on 13 This one-to-31 second-year young ( April. males and 10 6 males ratio that the of ) , first-year young ( suggests original sample and 4 females). The sample has a high 279 represented an actual population of proportion of adult males (believed to 8650. This figure, based on just one re- be especially active in sexual search at capture, is obviously of little significance this time and place); immatures consti- but it does serve to demonstrate that the tute only 12.2 per cent. 279 snakes of the 13 April sample were drawn from a much and their The 13 April search that yielded 279 larger pool did not constitute substantial snakes resulted in the escape of many marking in a others because the aggregations under progress attaining fully-marked pop- ulation on the study area of the metal strips scattered in all directions Quarry Field. In late and October when they were uncovered. Females September of collections of snakes were made and young, missing from this sample 1968, in Field on 16 and a com- that consisted mostly of adult males, may Quarry days bined of 184 was obtained, not in- have been present within the field but sample the that had less inclined to trail other individuals and cluding hatchlings emerged in late summer. This included 14 form aggregations (see section on Com- sample individuals from the 13 collection. position of the Population). Or they April The one-to-13 ratio in this collection may have been absent from the field, a total in of still concentrated at hilltop limestone suggests population spring 13 X 279 or 3630 in outcrops where they had hibernated. (950 per hectare) this field. However, the long interval Consideration of all available data between 13 April and the October- suggests that the 279 snakes captured on November resampling lessens the value 13 April 1968 were mostly residents of of the calculation. Population changes, Quarry Field and that they were only with dispersal and replacement of some a small part of the population present individuals, would have occurred in the there. Subsequent study by Richard L. interval. Lattis, trailing ringneck snakes equipped A index based with radioactive tags, has shown that the population upon is useful only if metal strips are not focal points of the capture-mark-recapture certain can be made about snakes' activities, and are not used regu- assumptions the stability and spatial relationships of larly by any individuals nor do they the it should be limited to constitute an essential part of the local population: a definite area and the individuals habitat. Instead the strips are used from marked should distribute themselves ran- time to time by snakes in the immediate their survivorship or difficulty of vicinity when they happen to provide domly; should not be affected; there shelter with optimal thermal and hygric capture in the conditions. Most of the snakes most of should be no reproduction popu- lation or else it should be measurable. the time are using shelters such as the From what is known about the Dia- surface mat of dead vegetation, where the following state- they cannot be found readily. Although dophis population, ments these many of the 279 snakes in this sample bearing upon problems may be made. 1. Most individuals most of were caught at other times, over a ten- the time within areas much smaller year period, they collectively never made stay than those There is sometimes up more than a small percentage of any sampled. and hi- one sample. a shift between summer range 42 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY bernaculum or place of egg-laying. 2. As in other vertebrates some individuals t/3 a may wander in a random manner as transients, but most stay in the same < are CO a> o^ ^H 10 -f 00 00 place, and sometimes recaptured xt< ^ oq o t- O 00 w --< 00 i> -* ^ t- CO ^ within a few meters of a former capture « .3 t- CD site after several years. 3. Individuals t- < some deleterious effects from u experience a and but '^ o marking handling, certainly I u 01 o o o in o most survive. No definite instances of s O CO o o CO '^ O t- Tt^ 01 00 H t^ CO in ^ CO mortality were observed. 4. Reproduc- < tion occurs only once in the annual cycle U I and young constitute a discrete size < from older snakes, ^ group distinguishable QJ C 00 O 1> CO t- c^l O o — -^ TS t^ a> 00 ^ CD CO CO so that they do not complicate capture- a b CO in 01 o '4-* 0000 ratios. -<" 000 recapture 3 .M .W 4-> 4-* i:li traits in view lU o IJ O CD CO CO CO t- 00 In view of these and CC -rt Q CO of the fact that no other method is avail- W H < able to measure populations even in c general terms, it seems worthwhile to U .3 i-l Qj a o a "Petersen Index" to the Dia- < CO CO CD t^ CO CO 00 apply in 00 '^ in CO CO CO U 03 lU CO I—I CO CO CO CO daphis population studied. Some work- ers have rejected capture-recapture in- < PM dices as a means of censusing snakes on < the that the figures grounds published c from studies of this are too erratic 3 type H CO there is in >x to be acceptable. Yet nothing bc O c the known of snakes population ecology £f H a o that makes capture-mark-recaptin-e tech- S 'C z w nique inapplicable to them. In general, o Ph snakes are difficult to census because u11 are secretive and it is difficult to < they z obtain adequate samples. However, each w case should be on its own merits, o judged H the size of the and Z depending on sample O the extent to which the theoretical as- z sumptions of a Petersen Index can be demonstrated to be satisfied. O c« in in U In my study Quarry Field (3.80 hec- I—( H 'a'? and House Field tares) (5.76 hectares) z u a a •ca -da were sampled on hundreds of occasions Q < < < < Pm I I but with the possible exception of 13 z o cj o o the oM April 1968 snakes captured on any H < one day were too few to be used as a .2 S S ^ separate sample. By combining many Oh >> CD t- O J.H CO CD day to day samples, adequate presam- « 2 2 pling and resampling periods within a C spring or fall season were obtained in several instances. J < Table 10 shows seven censuses in five different years in House Field and FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 43

for ratio Quarry Field. Calculated figures recapture and calculation of a fig- population density ranged from 719 to ure for the population that is too high. 1849 per hectare, with a mean of 1266 per hectare for all seven calculations COMPOSITION OF THE combined. Individuals are long-lived, POPULATION and variation in year-to-year reproduc- Age structure.—Age structure of the tive success would not be sufficient to adult population was calculated after about the fluctuations which must bring analysis of the records of individuals be caused biased or by inadequately marked while young and recaptured as small The and lowest samples. highest adults (Figs. 14-19, Tables 11-14). These are far from the mark. figures probably records, combined, show that length is Rapid seasonal changes in kind and highly correlated with age, so that each amount of activity and in the ratios of individual may be assigned to a most sex- and age-groups in samples hinders probable age group on the basis of its census and prevents eff^ective use of re- measurements. Within each age group finements of the capture-recapture index, lengths vary over a wide range but tend such as have been proposed in the to form normal curves, with a clustering "Hayne Method" and the "Jolly Method." of records near the mean and progres- index does A crude capture-recapture sively fewer in successive stages of de- not provide a precise measure of the viation from the mean. Each age group population, as has been demonstrated by exceeds younger age groups in mean several investigators. Nevertheless, in length, but successive annual increments this instance, and with secretive animals become progressively smaller. Samples in general, it does provide better infor- are smallest for the relatively old snakes, mation about numbers than do direct so that the trends of growth and survival counts, and at least indicates the order become increasingly obscure. of magnitude of the population. It sug- The graph in Figure 14 shows some gests that in favorable habitat population inconsistencies in the older age groups; densities of ringneck snakes are often for instance ten-year-old males in the between 1000 and 1500 hectare. 274.5 per sample averaged slightly larger ( ± It cannot be stated with any degree 1.84 mm S-V) than eleven-year-olds (273.0 of assurance whether the census figures ±2.10). Such irregularities may result obtained tend to err on the low side or from inclusion of occasional stunted in- the high side. Even the lowest census dividuals or those of unusually acceler- that figure, of 719 snakes per hectare, would ated growth. Recognizing growth seem excessively high for most kinds of continues in adults, but becomes pro- vertebrates, but all evidence suggests gressively slower with increasing age, that Diadophis pinwtatiis actually does and that there is a consistent difference attain high densities. The methods of in sizes of the sexes at any given age, obtaining samples, by returning regu- the growth curve has been adjusted by in Table 14. larly to certain favored spots to turn slight alterations as shown that the annual re- sheltering objects or to check live-traps, The table indicates next would tend to favor recapture of certain duction from any age class to the localized individuals and would increase older class is consistently between 20 23.4 the ratio of recaptures to new captures, and 30 per cent, and averages per cent for fe- resulting in an erroneously low census cent for males and 26.8 per the 1458 figure. On the other hand, wandering males. For example, first-year tendencies of some individuals, which males make up 25.2 per cent of the en- 92 might leave the study area after being tire sample of 5814 males and the marked, with replacement by newcom- males in the size range (275-277 mm) individuals make ers, would result in an erroneously low typical of eleventh year 44 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY

Table 11. —Composition of a Population of 9162 Diadophis punctatus Captured and Marked on the Reservation, 1958-1969.

Number Size Range Number of Size Range Total Male to of Males of Males Females of Females Number Female Ratio

Adults 3436 215-351

Second-year young __ 920 First-year young __._ 1458 Total 5814 FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 45 one population in this composite, mini- mizing the seasonal and year-to-year differences that characterize the smaller samples. In general the samples repre- sent either fall or spring in the pause between the summer growth periods; therefore, there are discrete annual age groups and in the younger snakes there are fairly distinct size groups. The 3436 adult males make up 39 per cent of the total in Table 11 and are much better represented than any of the other live classes. For example, the adult male to adult female ratio is 1.85 to 1. However, Table 12 shows that this ratio changes throughout the season of activ-

Table 12.—Changing Sex Ratio of Adult Diadophis punctatus Throughout Season of Acttvity.

Time 46 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY

Table 13.—Records of Large (and old) Males of Diadophis punctatus Captured and Recaptured, Indicating Potential Longevity.

Dates of Capture And Recaptvire FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 47 age of 3.89 eggs per clutch, their total study 94 records of eight species of pred- output would amount to 7210 eggs and ators on the Reservation and nearby this annual increment would add 78.6 areas were assembled; large series of per cent to the spring population. It is pellets of raptors and scats of snakes calculated that by the following spring were examined, hawk nests were visited the hatchlings from these 7210 eggs on many occasions to check for remains would be reduced by approximately of prey, and hundreds of live snakes of two-thirds to 2442 (1458 males, 984 fe- other kinds were palped to identify food males . 66 cent would of ) The per mortality objects. The records predation on be attributable to several causes, includ- Diadophis included 35 by Agkistrodon ing resorption or abortion of eggs, in- contortrix, 25 by Biiteo jamaicensis, 15 fertility or inviability of some of those by Coluber constrictor, 13 by Buteo laid, genetically defective hatchlings, platypterus, 2 by Lampropeltis triangu- predation on hatchlings and winterkill him and 1 each by Bubo virginianus, of the hibernating young. Crotahis horridus and Rana catesbeiana The age pyramid in Figure 19 is (Table 15). Sample size varied from based upon the actual numbers of snakes 2763 stomach examinations of Rana captured, but shows also the numbers of catesbeiana to only 20 records of feeding missing adult and second-year females in Lampropeltis triangulum. The 192 that might have been present but un- pellets of Bid)o virginianus represent detected (shaded ends of columns) if mainly the colder half of the year, with the sex ratio of 1.48 males to 1 female reptiles including Diadophis probably that was found in hatchlings is the real much less well represented than they ratio for the older snakes also. would have been in summer. Table 15 shows sample sizes and frequency of PREDATION Diadophis in food for the eight predator There are few published records of species, and attempts to show the rela- predation on Diadophis. In the present tive severity of predation on the basis of

— a Table 14. Sample of 9162 Ringneck Snakes Captured Over 12-Year Period ( 1958- 1969) Arranged in Size Groups and Supposed Annual Age Groups to Show Progressive Reduction in Numbers with Increasing Age. 48 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY

1000 500 NUMBERS OF SNAKES Fig. 19.—Age pyramid showing relative numbers of successive annual age classes of male and female Diadophis punctatus, based on figures in Table 14. Shaded portions of columns on female side rep- resent a part of the population not actually recorded but suspected to be present if the ratio of 1.42 males to 1 female found in first-year young is correct for adults also. frequency of Diadophis in the food, pop- mately 1700 Diadophis annually, a little ulation density of the predator, and less than 7.4 per hectare on the Reser- frequency of its feeding. Number of vation. However, this toll seems trivial meals consumed annually by each kind in view of the finding that Diadophis of predator on the 590-acre Reservation attains population densities of several have been estimated from censuses of hundred per hectare over extensive areas the predators and observations on the of favorable habitat. Presumably the frequencies of their feeding. Most kinds population is regulated by some other are present and active only in the mortality factors. warmer part of the year. For Bxiho vir- Other predators may be even more ginianus and Buteo jamaicensis, both important than those studied, although present throughout the entire year, the no records of their predation on Dia- estimated total number of meals is di- dophis were obtained. The eastern mole vided by two because it is unlikely that Scalopus aquaticus is one such suspect. predation on Diadophis would occur It is known to feed largely on earth- during the colder half of the year. worms and other invertebrates, but feed- The figures suggest that the copper- ing experiments with captive moles on head and blue racer combined account the Reservation demonstrated that they for 94 per cent of the known predation would catch and eat small reptiles at whereas none of the other six predators every opportunity. The spotted skunk accounts for as much as 1.5 per cent. (Spilo

cS

u Oh O

I—" t2 50 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY and succumbed. Blanchard, Gilreath and invertebrates but the trend of food habits Blanchard (in press) described this same differs in different parts of the range. ailment in the population that they stud- The locale of this field study is in the ied in northern Michigan, and Hender- ecotone between deciduous forest and son (1970) was handicapped by it in his grassland, at the eastern edge of the study of food and water consumption in Great Plains, near the center of the geo- confined ringneck snakes. graphic range of the ringneck snake, Winterkill may involve considerable which is a wide-ranging, polytypic spe- mortality in addition to predation of the cies. Selective pressures in this ecotonal hibernating snakes. Since Diadophis region have produced a population dif- lacks capacity for digging and can only ferent from any in other parts of the follow existing passageways or force its range, but many of the differences are way through loose soil, entombment or subtle. Snakes of the population studied entrapment might frequently occur are relatively small and stubby, highly through deposition or compaction of the variable in extent and pattern of dark soil around the hibernating snake. Freez- ventral markings, and more secretive and ing is also a potential source of winter subterranean in habits as compared with mortality, but the species penetrates into eastern populations (but perhaps less so regions having much more severe winter than far western and southwestern pop- climates than that of northeastern Kan- ulations). In feeding they have become sas, where this must be a relatively specialists dependent almost entirely on minor factor. earthworms, whereas elsewhere popula- tions are much more versatile but with DISCUSSION a tendency to specialize on plethodont salamanders United States Compared with small vertebrates in (northeastern and Appalachian region), on insects and general, the ringneck snake is K-selected other invertebrates United {semu Dobzhansky, 1951; MacArthur (southeastern States) or on small (Southwest). and Wilson, 1967; Pianka, 1970) in the reptiles variation in size and following respects: sexual maturity de- Geographic characters occurs layed (first breeding in third year), morphological along with variation in food but the brood size reduced (3.9 eggs per clutch, habits, variation does not produced once annually), young rela- morphological closely the behavioral variation. Gehl- tively large and well developed at hatch- parallel bach noted that in ing (36% of maternal length and 12% of (1974) Diadophis of near the maternal weight), life expectancy in- punctatus armji Texas, range of D. size remains creased (annual mortality in adults less p. regalis, relatively but in that area resembles than 25 per cent, with some individuals small, armji in its habits. When attaining ages of 15 years or more). All regalis ophiphagous individuals of the two were these traits make for stability of popu- subspecies confined occurred de- lations and except for the climax vegeta- together, mating the in size. Cannibalism tion itself the ringneck is one of the most spite disparity did not occur in these mixed al- stable elements in its community. Snakes pairs other small snakes were in general are notable for longevity, and though readily eaten when confined with the D. associated stability of populations. How- large p. Gehlbach found ever, considering the small size of the regalis. intergradation between the and ringneck, it has progressed farther than subspecies arnyi regalis in in the most in the direction of K-selection, a central and western Texas, but trend correlated with its secretive and Guadalupe Mountains he found isolated of inter- partly subterranean habits. populations both types with no The ringneck snake is a predator on breeding. Gehlbach speculated that various sorts of small vertebrates and small ringneck snakes similar to arnyi FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 51 and the more eastern subspecies, of lation was adequately measured; how- worm-eating habits and mesic habitats, ever, it probably often exceeds this figure are ancestral and that the large, ophi- and is the most important primary con- phagous regalis-type populations evolved sumer among the local vertebrates); from these snakes in Pliocene Madro- slender glass lizard, Ophisaurus attenu- Tertiary woodlands. An alternative pos- atus, 1.96 kg (in brushy former pastures sibility is that regalis is the more primi- dominated by tall brome grass); Great tive and that arntji and far eastern and Plains skink, Enmeces obsoletus, 1.86 kg far western subspecies are derived from (in rocky, open hilltop habitat in 1949, a regalis-like ancestor. Although evolu- but subsequently almost eliminated by tion conceivably could have proceeded unfavorable changes in the course of in either direction, regalis seems more vegetational succession); worm snake, generalized, that is, more like related Carphophis vermis, 1.67 kg (on rocky, genera of xenodontine snakes, but with wooded hillside and hilltop); five-lined less typical exhibition of the characters skink, Eumeces fasciatiis, 1.34 kg (in that distinguish Diadophis. Among such open woodland soon after livestock were generalized characters are: euryphagous removed, but succcssional trends subse- habits and predation on small verte- quently caused marked reduction); cop- brates, lack of a neck ring, and large perhead Agkistrodon contortrix, 1.23 kg; body size associated with large numbers cotton rat, Sigmodon hispidus, 1.11 kg of ventral and subcaudal scales and with (probably often exceeded by this primary 17 body scale rows, whereas other sub- consumer, but the cotton rat is also sub- species have only 15 to 13 rows. ject to drastic reduction and is usually much below this even at times and The abundance and availability of figure where habitat is earthworms as a food supply has per- places favorable). mitted attainment of remarkably high These incomplete and preliminary population density and biomass by the figures indicate that Diadophis attains snakes in the area of my study. Through- biomass levels comparable with those of out much of its range the ringneck is the most abundant vertebrate primary one of the less common species of snakes, consumers and much exceeding the other but in northeastern Kansas it probably local reptiles that feed upon inverte- outnumbers all other species combined. brates such as insects and annelids. the of On basis known population struc- Traits peculiar to the local popula- ture and the average weight of individ- tion of Diadophis must have arisen over uals of different sizes it is calculated that a long period of selection and adjustment 3.6 grams is a typical weight. A popula- to climate, habitat and biotic associates. tion of 1266 snakes per hectare (the On the other hand profound changes in of seven cen- average capture-recapture the species' ecology must have been suses) would thus have a biomass of 4.58 brought about within the past 125 years Of local vertebrates the kilograms. only as the region was altered from its orig- prairie vole (Microttis has ochrogaster) inal state by settlement, agriculture and been found to attain higher biomass over industry. Within the ecotone between extensive areas, with 7.41 kg per hectare deciduous forest and prairie, there was in an actual sample, but the vole is a formerly an abrupt transition from wood- primary consumer, and its population is land to but elim- subject to rapid and drastic change. grassland, tree-cutting, Other vertebrates of the Reservation ination of prairie fires, and pasturing of known to occur, at times, in biomass ex- livestock destroyed the clear-cut bound- ceeding 1 kg per hectare include the aries and created a much more extensive cottontail, Sijlvilagus fioridanus, 3.88 kg transitional zone with a mixture of wood- (in the only instance in which a popu- land and prairie types of vegetation that 52 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY provided better habitat for ringneck are on record no actual observations of snakes than either type in its pure form. population changes in Diadophis, it may Meanwhile the common and adaptable be speculated that the vastly improved earthworm Allolohophora caJU^inosa, in- habitat and food supply resulting from troduced from the Old World, became man's alteration of the original forest- established in a thriving population that prairie ccotone, caused a population ex- provided an abundant new food supply plosion of the snakes. Perhaps they are for the ringneck snake. Although there more abundant now than ever before. LITERATURE CITED

Anderson, P. 1965. The reptiles of Missouri. DoBZHANSKY, T. 1951. Gcuetics and the ori- LTm\'. Missouri Press, Columbia, xxiii + gin of species. Columbia Univ. Press, New 330 pp. York. Barbour, R. W. 1950. The reptiles of Big Dundee, H. A., Miller, M. C. 1968. Aggre- Black Mountain, Harlan County, Kentucky. gative behavior and habitat conditioning by Copeia, 1950:100-107. the prairie ringneck snake, Diadophis punc- Blanchard, F. N. 1926. Eggs and young of tatus arnyi. Tulane Studies Zool. Bot., 15: the eastern ringneck snake Diadophis punc- 41-58. tatiis edwaidsi. Pap. Michigan Acad. Sci. Ernst, S. G. 1962. Notes on the life history Arts, Lett., 7:279-292. of the eastern ringneck snake. Turtox News, Blanchard, F. N. 1930. Further studies of 40 (10): 266-267. the eggs and young of the eastern ringneck Fitch, H. S. 1951. A simplified type of funnel snake Diadophis punciatus edwaidsi. Bull. trap for reptiles. Herpetologica, 7:77-80. Antivenin Inst. Amer., 4(1):4-10. Fitch, H. S. 1956. Temperature responses in Blanchard, F. N., 1937. Eggs and natural free-living amphibians and reptiles of north- nests of the eastern ringneck snake, Dia- eastern Kansas. Univ. Kansas Publ. Mus. dophis punctatus edwardsi. Pap. Michigan Nat. Hist., 8(7):417-476. Acad. Sci. Arts, Lett. 22:521-532. Fitch, H. S. 1958. Home ranges, territories Blanchard, F. N. 1942. The ringneck snakes, and seasonal movements of vertebrates of genus Diadopliis. Bull. Chicago Acad., Sci., the Natural History Reservation. Univ. 7(1):1-144. Kansas Publ. Mus. Nat. Hist., 11(3) :63-326. Blanchard, F. N., Finster, E. B. 1933. A Fitch, H. S. 1960. Autecology of the copper- method of marking living snakes for future head. Univ. Kansas Publ. Mus. Nat. Hist., recognition with a discussion of some prob- 13:85-288. lems and results. Ecology, 14:334-347. Fitch, H. S. 1963. Natural history of the Blanchard, F. N., Gilreath, R., Blanchard, racer, Cohiher constrictor. Univ. Kansas F. C. in press. The eastern ring-necked Publ. Mus. Nat. Hist., 15:351-468. snake (Diadophis punctatus edwardsi) in Fitch, H. S. 1965. An ecological study of the northern Michigan. Jour. Herpetology. garter snake, Thamnophis sirtaJis. Univ. Buikema, a. L. Jr., Armitage, K. B. 1969. Kansas Publ. Mus. Nat. Hist, 15:49.3-564. The effect of temperature on the metabolism Fitch, H. S., Fleet, R. R. 1970. Natural of the prairie ringneck snake, Diadophis history of the milk snake (LampropeUis punctatus arnyi Kennicott. Herpetologica, trian^tdum) in northeastern Kansas. Herpe- 25:194-206. tologica, 26(4):387-396. F. R. 1974. relations Clark, D. R., Jr. 1966. A funnel trap for Gehlbach, Evolutionary of southwestern snakes small snakes. Trans. Kansas Acad. Sci., ringneck (Diadophis .30:140-148. 69(l):91-95. punctatus). Herpetologica, H. W. 1973. Defensive tail Clark, D. R. Jr. 1967. Experiments into se- Greene, display snakes and Jour. lection of soil type, soil moisture level, and by amphisbaenians. Herpe-

: 14.3-161. temperature by five species of small snakes. tology, 7(3) Trans. Kansas Acad. Sci., 70:490-496. Henderson, R. W. 1970. Feeding behavior, and water of Dia- Clark, D. R. Jr. 1970. Ecological study of digestion requirements dophis punctatus arnyi Kennicott. Herpe- the worm snake, Carphophis vermis ( Ken- nicott). Univ. Kansas Publ. Mus. Nat. tologica, 26(4):520-526. Hist., 19(2):85-194. Klauber, L. M. 1956. Rattlesnakes. 2 vols. California CoNANT, R. 1948. Regeneration of clipped LIniv. Press, Berkeley. subcaudal scales in a pilot blacksnake. Chi- MacArthur, R. H., Wilson, E. O. 1967. The cago Acad. Sci., Natural History Miscel- theory of island biogeography. Princeton lanea, no. 13:1-2. Univ. Press, Princeton, New Jersey. FITCH: A DEMOGRAPHIC STUDY OF THE RINGNECK SNAKE 53

Myers, C. W. 1965. Biology of the ringneck Smith, A. K. 1973. Feeding strategies and snake, Diadopliis punctatus, in Florida. population dynamics of the bullfrog (Rana

Bull. Florida State Mus., 10:43-90. catesbeiana). ( Unpublished dissertation, Noble, G. K., Clausen, H. J. 1936. The ag- University of Kansas Library). gregation beha\'ior of Storeria dekayi and Vax Dexburgh, J. 1922. The reptiles of west- other snakes with especial reference to the ern North America. Occas. Papers Cali- sense organs involved. Ecol. Monogr., 6: fornia Acad. Sci., 10:1-1028. 269-316. Wright, A. H., Wright, 1957. Handbook of Petersox, H. W. 1956. A record of \'iviparity snakes of the United States and Canada. in a normally oxiparous snake. Herpetolog- Comstock Publ. Associates, Cornell Univ. ica, 12(2): 152. Press, vol. 1, xviii + 564 pp. PiAXKA, E. R. 1970. On r- and K-selection. American Naturalist, 104:592-597.

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