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Brigham Young University BYU ScholarsArchive

Theses and Dissertations

1972-04-18

Nesting of the white-faced ibis (Plegadis chihi) of Utah Lake

Kenichi David Kaneko Brigham Young University - Provo

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BYU ScholarsArchive Citation Kaneko, Kenichi David, "Nesting of the white-faced ibis (Plegadis chihi) of Utah Lake" (1972). Theses and Dissertations. 7796. https://scholarsarchive.byu.edu/etd/7796

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NESTING OF THE WHITE-FACED IBIS (PLEGADIS CHIHI)

ON UTAH LAKE

A Thesis

Presented to the

Departre nt of Zoology

Brigham Young University

In Partial Fulfillment

of the Requirements for the Degree

Master of Science

by

Kenichi David Kaneko

May 1972 Tis thesis, by Kenichi David Kaneko, is accepted in its present form by the Department of Zoology of Brigham Young University as satis­ fying the thesis requirement for the degree of Master of Science.

1 IK'llf Date,;/2fl z:v

Typed by Susan Stockwell

ii ACKNOWLEDGMENTS

Deepest gratitude is expressed to Dr. Herbert H. Frost for suggesting the problem and for his patient and unobtrusive guidance of the research. But more than this, he has been a friend.

My appreciation to the other members of my committee, Dr. Joseph

R. Murphy and Dr. Glen Moore, for their critical reading of this manu- script and for their helpful suggestions in both research and writing.

Thanks must be given to Dr. Stephen L. Wood for identifying the food items and to Dr. Robert E. Elbel for identification of the ecto- parasites. Thanks, also to the Zoology Department for providing equipment and supplies.

Above all, my wife, Lorraine, deserves special recognition for patiently and unselfishly assuming a larger share of family responsibil- ities as her contribution to the research. Appreciation is expressed for her constant love and encouragement, especially in the numerous times of frustration.

iii TABLE OF CONTENTS

Page ACKNOWLEDGMENTS. . . iii LIST OF TABLES . vi LIST OF ILLUSTRATIONS. . . . . vii INTRODUCTION . 1 Review of the Literature 2 THE STUDYAREA . . . . 4 METHODSAND PROCEDURES 10 RESULTS . . . . 16 Earliest Observation . . . 16 Blinds . . . 16 . . . . . 16 Clutch Size . . . . 21 Measurements 21 Hatching . . 22 Measurements of the Young . . . . 22 Leaving the . 22 Food Items 27 Ee toparasi tes 27 Banding . . 27 Reaction to Human Handling . 28 DISCUSSION . . . . . 29 A New Record . . 29 Earliest Arrival Dates . . 29 Blinds . . . . . 30 Nests . . . 32 Desertion of Nests . 35 Clutch Size . . . 38 Egg Measurements . . . 40 Egg Volumes . . . 41 Pipping ...... 45 Hatching ...... 48 Measurements of the Young ...... • 51 Development of the Young . . . 53 Age at Leaving Nest ...... 58 iv Page Flight ...... 59 Food Items of Young ...... 60 Ectoparasites . . . 63 Wintering Grounds . . . • . . . . . 63 Banding ...... 66 SUMMARY. . . . 67 LITERATURECITED 69

V LIST OF TABLES

Table Page

1. Summary of the 21 nests selected for study in 1971 ••• 17

2. Food items found in the regurgitant of five nestlings 27

3. Reactions to human handling by White-faced Ibis nestlings of various age groups ••• 28

4. Comparison of volumes and weights of White-faced Ibis of various sizes (modified from Kotter, 1970) 43

5. Numbers of food i found in 209 White-faced Ibis stomachs collected in northern Utah, 1951-1953 (Petersen, 1953, IN Ryder, 1967) • • • • • • • • • • • • • • • • • 61

6. Places of recovery of White-faced Ibises banded in Utah as nestlings (Ryder, 1967) ••••• 64

vi LIST OF ILLUSTRATIONS

Figure Page Frontispiece--White-faced Ibises in flight ...... ix 1. General location of the study area ...... 5 2. Provo Bay of Utah Lake showing the location of the intensive study area •••••• ...... 6 3. Locations of nests and blinds in the intensive study area • • 12

4. , tarsometatarsus and primary of White-faced Ibis nestling. is approximately 13 days old. • • • 14 5. A tall nest, standing 965rrrrn above 608rrrrnof water ...... 19 6. A low nest, situated at water level ...... 20 7. Average daily increase in weight, showing number and range of measurements per day. • • • • • • • • • • • • • 23

8. Average daily increase in feather length, showing number and range of measurements per day ••• . . . . . 24 9. Average daily increase in tarsometatarsal length, showing number and range of measurements per day 25

10. Average daily increase in beak length, showing number and range of measurements per day. • • • • • • 26

11. White-faced Ibis nest with three eggs; note pip in upper egg. Eggs are paler blue than actual color. • • • 39

12. Comparison of volume with transverse axis of egg of White-faced Ibis, showing nearly linear relationship 46

13. Comparison of volume with longl tudincil axis of eggs of White-faced Ibis, showing lack of linear relationship • • 47 14. Distribution of egg hatching from June 8-27, 1971 . . . . . 50 15. Direct comparison of the linear measurement of beak, feather, and tarsometatarsus of nestling White-faced Ibises ••••••• 52

vii Figure Page

16. White-faced Ibis nest containing (counter clockwise from egg) pipped egg, two- and three-day old nestlings. Note cowering posture of nestlings •••••••••• 55

17. States in Mexico where White-faced Ibises have been recovered or seen. 65

viii White - faced Ibi ses in flight .

ix INTRODUCTION

Few references have been made to the status of the White-faced

Ibis fPlegadis chihi (Vieillot)] (A.O. U., 1957) in Utah sou th of the ("., Salt Lake Valley and none contain~reports of nesting or breeding.

Cottam (1927a) considered the bird a fairly common migrant and summer visitor in Utah County. Hayward (personal interview) stated that he did not think the bird nested on Utah Lake. Local residents reported to Henshaw (1875) that the "black snipe" was common on Utah Lake in the spring and fall and he thought it might breed in the vicinity.

Although the White-faced Ibis has been observed feeding in the irrigated pastures of Utah County for many years, nesting colonies have not been reported; consequently, information concerning nesting success, hatching success, development of the young, food preferences, and popu- lation status is not available.

The Provo Bay area of Utah Lake supports a large stand of hard- stem bulrush (Scirpus acutus), the same species preferred by the ibis for nesting and roosting at Bear River National Refuge (Smith, personal interview). This stand of bulrush seems to be the prime poten- tial nesting area of the ibis in Utah County. According to present information, Provo Bay may be diked by the Burea.u of Reclamation (U.S.

Department of Interior) as part of the Central Utah Project, effectively removing this nesting area.

The purposes of this study were twofold: First, to determine if, indeed, the White-faced Ibis nested in Provo Bay; and, second, to gather 2 information to help define the role of the White-faced Ibis in the ecol- ogy of Provo Bay, Utah Lake and the surrounding area.

Review of the Literature

The White-faced Ibis is an inhabitant of many marshes of North

America but is found mainly in the western regions. Observations or collections of this bird have been made in the southern parts of Alberta and British Columbia, , and in every state west of the 89th meri- dian except Alaska (Ryder, 1967). Breeding colonies have been reported in Florida (Brewster, 1886); Louisiana (Bent, 1926); Minnesota (Peabody,

1896); Kansas (Moosman, 1952; Zunanich, 1963); Texas (Merrill, 1878;

Quillion and Hallernan, 1918; Bent, 1923; Griscom and Crosby, 1925); New

Mexico (Anthony, 1892); Colorado (Peyton, 1937; Bailey and Brandenburg,

1941; Ryder, 1950); Oregon (Willet, 1919; Scott, 1966; Ryder, 1967);

Idaho (Arvey, 1947); California (Grinnell, 1902; Sharp, 1907; Willet and Jay, 1911; Tyler, 1913; Lamb, 1922; Small, 1961); Nevada (Ridgway,

1877; Giles and Marshall, 1954, Ryder, 1967); Nebraska (Swenk, 1917);

Wyoming (Scott, 1954a); Utah (Ridgway, 1875; Treganza, 1914; Bent, 1926;

Cottam, 1927a; Parkinson, 1933; Bee and Hutchings, 1942; Lockerbie, 1944;

Woodbury, Cottam and Sugden, 19t,9; Scott, 1954b; Weller, Wingfield and

Low, 1958; Kotter, 1970). Mearns (1890) and Swarth (1914) stated that this ibis breeds or probably breeds at Mormon Lake in the Mogollon

Mountains of Arizona, but Phillips~ Marshall and Monson (1964) reported that there were no positive breeding records for the state. Breeding colonies have also been reported in Mexico, Brazil, Argentina and Chile

(Bent, 1926; Na:unburg, 1926; Friedmann, Griscom and Moore, 1950; Palmer,

1962; Weller, 1967). 3

In Utah, the greatest number of breeding records are associated with the Bear River National Wildlife Refuge, Box Elder County (Bent,

1926; Cottam, 1927b; Bee and Hutchings, 1942; I.ockerbie, 1944; Woodbury,

Cottam and Sugden, 1949; Weller, Wingfield and Low, 1958). Other breed- ing colonies in the state have been reported at Farmington Bay, Davis

County (Ryder, 1967; Kotter, 1970), Ogden Bay-Howard slough, Weber

County, and Springs, Tooele County (Ryder, 1967), Black slough, Salt

Lake County (Bee and Hutchings, 1942), and Salt Lake valley (Ridgway,

1875). Kotter's (1970) master's thesis is the only detailed study of the

White-faced Ibis in Utah. Allen G. Smith (personal communication) has been studying the effects of pesticides on the ibis at Bear River

National Wildlife Refuge, but his results have not been published. 4

THE STUDYAREA

Provo Bay (Fig. 1), an arm of Utah Lake, is located immediately south of the Provo Airport and extends eastward to Interstate 15 and southward approximately 4.8km. The northeast quadrant of the bay (Fig.

2) is bordered on the north by a row of large cottonwood trees and on the east by Interstate 15. A dense stand of hardstem bulrush (Scirpus acutus) grows along the north and east sides of the quadrant and extends up to 305m from the shore. The north side of the quadrant extends about

1.6km west from the University Avenue interchange on Interstate 15. The east edge extends south from this same interchange to the Springville interchange, about 2.4km. Water flows into this area of the bay via the mill race on the north and Hobble Creek on the south. Water from irri- gation of adjacent agricultural lands also drains into the bay.

In 1970, the White-faced Ibis nested along the north side of the quadrant in the westernmost 275m of bulrushes. In 1971, the nested along the open-water side of the bulrushes growing on the eastern edge of the quadrant. The latter colony was located west of two leaf-bearing,

9m-tall cottonwood trees. These trees could be seen standing about 200m due west of the midway point between the two interchanges on Interstate

15 and differed from the other trees in the mar-sh in that they were still alive. This colony was 45m wide a11J extended i.lOm southward from an abandoned half-submerged fence (Fig. 2).

Scirpus acutus Muhl. (family Cyperaceae) has been described by

Welsh, Treshow and Moore (1965) as an emergent along lakes and streams. 5

; 'UTAH N

UTAH

LAKE

S.pring-vllleQ

Spanfsh Fork

Fig. 1. General location of the study area. ( ,, ...... ) 1 I KOVO - I ,, ...... -- , r, ,,j \ - I ! /'l I trees N I \ "\ f I \ \J \.. - I \ l ' ) ,,,,I ( UTAH ( J \ ) LAKE \ '>" I PROVO I / ..... r- - ' ) Hobble / .... ;- 1 Creek ' ..... \ ,..__ ...... ) BAY '- .... V\ \ '_, ...... r,.,... ,,.,,- ' 1-15 ,, ..... ,, ' / .... ,, ' '., ' \ / ' _ ' I I / I I

Fig. 2. Provo Bay of Utah Lake showing the location of the intensive study area.

a- 7

The water in which the bulrush grew was almost uniformly 61cm deep in early June. Few bulrushes grew in water that was deeper or shallower than this. By the third week of July, the water level had dropped to

51cm, but this did not appear to affect the growth of older plants or hinder the emergence of new plants. 1• acutus grew to a height of about

3m from the bottom in dense clumps that limited vision to less than 3m in the nesting area. This is the same species of bulrush preferred for nesting by the ibises at Bear River National Wildlife Refuge (Smith, personal interview). A different species, the alkali bulrush (1• paludosus), is preferred at Famington Bay (Kotter, 1970).

1• acutus grows in many places around the shores of Utah Lake, but the stands are sparse. Powell Slough, 8km north of Provo Bay, supports a stand of bulrush similar in density to that in Provo Bay.

However, the total area of dense bulrush there was considerably less than that at Provo Bay and, apparently, was not extensive enough for ibis breeding. The White-faced Ibis nested only on Provo Bay in 1970 and 1971.

Human disturbances in the nesting area were minimal. The author was the only person in the nesting area during the study period with the exception of seven days when he was accompanied by one person each day.

People frequently hunted carp with bows and arrows in the shallow waters along the frontage road parallelling Interstate 15, but the author saw only one hunter approach within 100m of the nesting area in 1971. Power boats were excluded by the shallow water of Provo Bay and manual craft were hindered by the thick bulrushes.

The only observed in the marsh was the muskrat (Ondatra zibethica) swimming in the open areas in the bulrushes. Three muskrat 8 houses in various stages of construction were found within the boundaries of the ibis colony.

A number of other bird species were found nesting in the marsh with the ibis. Black-crowned Night Herons ( nycticorax) were concentrated in a colony of 25 nests in the center of the ibis colony with 5 more nests scattered through the marsh. Hatching began during the last week in April and continued until the middle of June. Most had left the nests by the time the ibises began hatching. Nine Snowy Egret (Leucophoyx thula) nests were found together on the• east end of the center of the ibis colony. Hatching of egret eggs was concurrent with that of the ibis. Five Western (Aechmophorus occidentalis) float- ing nests, averaging 2.6 eggs per nest, were found in the northern third of the ibis colony. They had hatched and left the nests by June 10.

Eight occupied Yellow-headed Blackbird (Xanthocephalus xanthocephalus) nests were found in the northern third of the ibis colony. Five unoccu- pied nests were also found. Long-billed Marsh Wren (Telmatodytes palustris) nests were scattered throughout the marsh. Six occupied nests investigated contained a total of 24 eggs and young. One young and five adult Great Blue Herons (Ardea herodias) were seen in the ibis colony. Two empty heron nests were found in dead trees. Five Cinnamon

Teal (Anas cyanoptera) were seen daily in a large open-water area near the center of the study area. Five downy young accompanied by the adults were swimming and sunning in the same area in July. Ruddy

(Oxyura jamaicensis) were observed swimming in the marsh and one young was seen in July. Redheads (Aythya americana) were frequently encoun- tered, but no young were seen. Yellowthroats (Geothlypis trichas),

American Coots (Fulica americana), and Black-necked Stilts (Himantopus mexicanus) were commonly observed and heard in the marsh, but no young 9 or nests were found. Double-crested (Phalacrocorax auritus) and Forster's Terns (Sterna forsteri) fished daily along the western edge of the colony. A (Chordeiles minor), a Marsh

Hawk (Circus cyaneus) and a California (Larus californicus) were seen to fly close to the colony. No interaction with the White-faced

Ibis was noted with any of the above-mentioned species. 10

METHODSAND PROCEDURES

The study was conducted during June, 1970, and in the spring and summer of 1971.

Two blinds were constructed to facilitate observations of activities at the nest. Wooden platforms were made in a four-foot square with a frame of 2 X 4's and flooring of 1 X 6 1 s. A 5cm hole was bored in each corner to allow passage of a 3.8cm steel conduit, 3m long, which supported the platform. The adjustable platform was held at the desired level by two U-bolts at each corner, arranged perpendicular to each other, passing around the conduit and through the 2 X 4 frame. A piece of canvas 1. 3m square and 1. 8m tall, painted dark green, covered the frame. The bottom 60cm of one corner of the canvas was left unsewed to serve as a doorway, which was held closed by safety pins. A metal kit- chen chair was used in each blind. After the blind was set in place and nearby nests located, small slits were cut at suitable heights to allow clear views of the nests while seated in the chair and while standing.

The 3m poles were sufficiently tall to allow almost 1.8m of headroom while holding the platform above about lm of water after the blind had settled into the mud.

One blind was set up near the west boundary of the northern quarter of the nesting area in an open spot slightly larger than the blind. From this vantage point, seven ibis nests, one Long-billed Marsh

Wren nest, and one Western Grebe nest, all active, were visible. The second blind was placed near the center of the nesting area in an opening 11 occupied by some small, dead trees. From this blind, four ibis nests

(two under construction) and one Black-crowned nest were observable (Fig. 3).

Twenty-one nests were selected for intensive observations and measurements of the young. These nests were marked by standing a 92cm piece of lath upright in the mud nearby. Fifteen centimeters of the lath had been dipped in white paint and a black number painted on the white area. These nests were located in the northern half of the study area where nesting was most concentrated. Measurements were made of the height of the nest cup from the marsh bottom. Water depth was measured by marking one-inch increments up from the foot to the thigh of the chest waders worn by the author. Nest height could then be measured from water level without submerging the end of the steel tape, and the total height was found by adding this measurement to the depth of the water as deter- mined on the leg of the waders. Measurements were made between nests to determine the proximity of nests to each other in the most densely popu- lated portion of the north half of the study area. Two nests were collected for faunal examination in a Berlese funnel and for comparison of nest material from nests of two different heights. The breadth and

thickness of each nest was measured as well as the average thickness and length of each piece of nesting material. found in the nest materials were ccLlected for identification.

Average clutch size was detel1idned for the entire colony.

Abandoned nests were included in this measurement but incomplete or unused nests were not. A nest was considered abandoned if it contained at least one egg, but was not incubated at any time. A nest was incom- plete if construction was halted sometime before the nest cup was built I ;1

IJ:-e ee be... e. e X lC X i,''"/"'ix x ,(../ .,.,\ XJ'/ -., :\1/1,)(

: X X. X X

= Open water

Fig. 3. Locations of nests and blinds in the intensive study area. 1--' N 13

and construction was never resumed. A nest was considered unused if

the nest cup was completed but eggs were not laid in the nest.

Egg width and length were measured with dial calipers accurate

to one-twentieth (0.05) of a millimeter. By the time the colony was

located, the clutches were essentially complete and it was not possible

to make measurements comparing eggs of the same clutch (Kotter, 1970).

Volume of the eggs was calculated by using the formula V = 0.526 LB,2 where V = volume, L = longitudinal axis and B = transverse axis (Romanoff

and Romanoff, 1949).

Hatching success was determined by dividing the number of young

that lived at least one day by the total number of eggs in the marked

nests.

Four measurements (weight, length of tarsometatarsus, feather

shaft and bill) were taken daily of the nestlings to determine patterns

in growth rates. Weight was measured with an Ohaus Dial-0-Gram balance

accurate to one-tenth of a gram. Tarsometatarsus, feather shaft, and

bill (Fig. 4) were measured with a plastic, 150mm ruler. The tarsometa-

tarsus was measured from its point of enlargement below the ankle to its

articulation with the middle (#3) toe. Feather shaft length was measured

from the follicle wall to the distal end of the sheath before feather

emergence and to the distal end of the shaft after emergence. The

feather used for the measurernents was the third primary from the distal

end of the right wing. The bill was measured from the corner of the

mouth along the side to the end of the-bill. This method allowed the

150mm ruler to be used as a restraining device on the head of the nest-

Ung and necessitated the use of only one hand to hold the ruler, leaving

the other hand free to control the bird.

\. 14

Fig . 4 . Beak , tarsometatarsus and primary feather of White - faced Ibis nestling . Bird is approximately 13 days old . 15

Food items were determined by analyzing regurgitants from the nestlings. Regurgitants were not systematically collected as this would have necessitated direct observation by the author of the feeding process and the immediate inducement of regurgitation in the nestlings. At no time did the author see the feeding of a nestling by an adult. Food items were obtained by the fortunate coincidence of the author handling some of the nestlings for measurements, apparently immediately after feeding had taken place, and the disposition of the nestlings being such that they regurgitated in the author's hand.

Ectoparasites were picked from a nestling which died at the age of 16 days. These were sent to Dr. Robert E. Elbel for identification.

U.S. Bureau of Sport Fisheries and Wildlife aluminum bands were placed on the left leg of as many nestlings as could be caught during the seasons of 1970 and 1971. 16

RESULTS

Earliest Observation

The first White-faced Ibises reported for Utah County in 1971 were seen by a fellow student on April 15 at the east end of Provo Bay.

He said that 40 birds flew over his head at an altitude low enough that he was able to make positive identification.

Blinds

A blind was erected on April 30, 1971, in the area used for nesting in 1970 so that the birds could become accustomed to it before nesting began. However, the birds did not nest in the same area in 1971.

The blind was moved to position number one (Fig. 3) on May 29, after the nesting site had been located. Blind number two was erected (Fig. 3)

on June 5. All eleven ibis nests visible from the two blinds were

abandoned within two days after of the blinds.

Ne.sts

Twenty-one nests (Fig. 3) in a densely populated portion of the northern half of the nesting colony were selected for intensive study.

Of the 21 nests, 11 remained active longer than two weeks after egg-laying was completed, five were abandoned almost immediately after completion

of egg-laying, and the remaining five were attended by adults and the

eggs incubated for not longer than two weeks after egg-laying was com-

pleted (Table 1). 17

Table 1. Summary of the 21 nests selected for study in 1971.

Height (cm) Eggs Nest No. 1 2 June 9 June 27 No./Nest No. Hatched Percent

Active Nests

3 101.8 93.9 3 3 100 4 160.0 deserted 3 2 67 5 157.2 152.4 4 4 100 6 152.4 127.0 2 1 50 8 116. 9 76.2 4 3 75 16 104.1 73.6 3 2 67 17 149.9 119. 3 4 3 75 18 109.2 83.8 3 3 100 19 101.8 63.5 4 4 100 20 81.2 73.6 3 2 100 21 116.9 68.5 5 5 100 Average 122.9 93.18

Inactive Nests

106.6 109.2 4 0 0 104.1 99.0 3 0 0 106.6 106.6 4 0 0 137.0 Toppled 4 0 0 138.0 132.1 4 0 0 147.2 144.7 4 0 0 129.4 127.0 4 0 0 122.0 109. 2 4 0 0 101. 8 94.0 2 0 0 114.4 116. 9 4 0 0 Average 120.6 115.4

1 2 Includes 61cm of water. rncludes 50.8cm of water. b aDeserted after study began. Deserted before study began. 18

Nest height varied from season to season and within a season.

In 1970, the nests observed were of nearly uniform height above the marsh bottom. By the author's estimate, the height of the nest cup

ranged from 60cm to 90cm from the muddy bottom. On June 9, 1971, the

21 study nests ranged in height from 81.2cm to 160cm, with an average

height of 122.9cm. By June 27, the average height had dropped to 93.2

cm. As indicated by Table 1, the 11 occupied nests changed 29.7cm in

average height, from 122.9cm to 93.2cm, while the abandoned nests changed

only 5.2cm (120.6 to 115.4). (This change is explained in the discussion

chapter under "Nests.") The tallest nest observed was outside the study

area and stood 205cm in bulrushes 255cm tall.

A regimen for the spacing of nests seemed to be lacking as nests

were placed without apparent regard for proximity to other nests. The

distances between nests ranged from 2m to 9m, with an average of 4.6m.

The primary material used in the building of nests was Scirpus

acutus. Tall bulrushes were bent at about 1.8m above the bottom toward

the center so as to form a platform. Large pieces of bulrushes were

then loosely woven to form the base of the nest. Finally, the nest cup was made from finer materials. Two nests of different heights were

selected for comparison of building materials. The tall nest (Table 1,

4f6) (Fig. 5) was 270mm across and 180mm thick. The materials averaged

620.4mm in length (range 250-llOOmrn) and 4.5mm in thickness, with the

thickest being 11.1mm. The nest cup was made of shredded S. acutus.

The low nest (Table 1, 4fo8) (Fig. 6) was 300mm wide and 260rmnthick. The materials averaged 293.1mm in length (range 90-1555rrnn) and 4.1mm thick,

the thickest being 17.0mm. The nest cup was composed of different types of materials, including one head of Eleocharis, a sedge which grows in wet areas, and some unidentifiable grass fragments. 19

ll 011

Fig. 5. A tall nest, standing 965 mm above 608mm of water. 20

,, ' I ,' : ,, , J j ' : •' I , : I . I., ,' ., ···1 \·~ / -- ,I . ,I - -. . , ' l l I \

',. --\'' ""'·, •,. -

Fig . 6. A low nest , sit uated at water level . 21

Invertebrates associated with the nests were collected prior to measuring by placing the nests in a Berlese funnel. The families

Lathridiidae (Order Coleoptera) and Coccidae (Order Homoptera) were common to both nests. The high nest contained representatives of the insect families Phloeothripidae (Order Thysanoptera) and Phalacridae

(Order Coleoptera) and the insect order, Microlepidoptera. The low nest contained representatives of the insect families Pyralidae (Order

Lepidoptera) and Anthicidae (Order Coleoptera) and the family

Adidae ( Arachnida).

Clutch Size

A census of nests and eggs was taken by dividing the nesting colony into three parts and counting one section per day. This was done before the birds were old enough to leave the nest and after it was reasonably certain that the clutches were complete. A total of 478 eggs were found in 151 nests, for an average of 3.17 eggs per nest. There were 11 nests with 1 egg each, 27 nests with 2, 42 with 3, 69 with 4,

1 with 5, and 1 with 6.

Egg Measurements

On June 9, the lengths and widths of 206 eggs in 71 nests were measured with the dial calipers. Extremes were (length X width in mm):

56.16 X 37.75; 45.90 X 36.70; 52.10 X 40.40; 55.45 X 33.60. The average length and width was 51.40 X 36.75.

Thirty-one nests were selected from the 71 nests mentioned above and an average volume was calculated using the dimensions of the first egg measured in each nest. The average volume for these 31 eggs was

36.93cc, with volumes ranging from 31.77cc to 44.84cc. 22

Hatching

Hatching began on June 8 and ended on June 27, 1971. Of the 72 eggs in the 21 study nests, 33 hatched for a 45.8 percent hatching success. In the 11 nests that were occupied during the entire nesting period, all hatched at least one egg. Of the 38 eggs in these 11 nests,

33 hatched for a success ratio of 86.8 percent. The observed hatching success for the entire colony was approximately the same as that for the

21 study nests. The 151 nests counted on June 9 contained 478 eggs. By

July 5, 215 nestlings had been banded, giving an apparent success figure of 45. 0 percent.

Measurements of the Young

See Figures 7, 8, 9, 10 for a summary of each of the measurements for weight increase and increases in length of feather shaft, tarsometa- tarsus and beak.

Leaving the Nest

The dates in this section indicate the time when a bird was of sufficient development to be absent from the nest at a distance which prevented recovery for measurements, even though measurements may have been made subsequent to the absence.

The earliest date at which birds were absent from the nest was

June 20, 1971. The last nestJ.ing in the study nests left the nest on

July 8.

Age at the time of leaving the nest varied considerably. The oldest was 24 days old and the youngest was 9 days. The average age for leaving the nest was 14.1 days. 23

400

5 4 E -Ol 3 -300 ..... 2. :c 6 (!) W 250

200 13

150 21 2.l 20

12 100 21 20 22 50 16 14 12 12 lo

2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 20 21 DAY

Fig. 7. Average daily increase in weight, showing number and range of measurements per day. 24

120

II

100

9

80

-E 5 ..s 7 :J: .... <.!) z 60 w _J 5

6 40 14

f3

18 23 IO I 20 16 20 22

2. '3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 2021 D A Y

Fig. 8. Average daily increase in feather length, showing number and range of measurements per day. 25

80

7

60 2 5 3 2

50 -E -E 5 :c 14 ._ 4 <.? z 21 12 w 19 ..J 20

20 17

9 10

l 2 3 4 5 6 7 8 9 10 JI 1213 1415 161718192021 DAY

Fig. 9. Average daily increase in tarsometatarsal length, showing number and range of measurements per day. 26

55

50 2

4 7

40-

17 - 35 E 6 E -:I: 30 22 19 14 I- Z·I (!) z 24 w 25 , _.J 22

2 18 14

9 10 15 8 9 10

5

2 3 4 5 6 7 8 9 10 l 1 12 13 14 15 16 17 I 8 19 20 21

DAY

Fig. 10. Average daily increase in beak length, showing number and range of measurements per day. 27

Food Items

Food items were obtained from five nestlings which regurgitated while being weighed. These items were identified by Dr. Stephen L. Wood

(personal communication) of Brigham Young University. The five nestlings were of ages 7 days, 10 days, 10 days, 17 days, and 17 days (Table 2).

Table 2. Food items found in the regurgitant of five nestlings.

7 days 10 days 10 days 17 days 17 days

O. Coleoptera Dytiscidae X X X X X Hydrophilidae X X X X X Staphylinidae X o. Diptera Chironomidae X Stratiomyidae X X X X X Syrphidae X Tabanidae X X

Cl. Arachnida Adidae X X

Snails X X X

Ectoparasites

Lice recovered from P~ chihi were identified as Plegadi- philus plegadis (Dubinin, 1938) by Dr. Elbel (personal communication).

Three flies were also recovered but have not as yet been identified.

Banding

Bands from the U.S. Bureau of Sport Fisheries and Wildlife were attached to the left leg of nestlings at least six days old. In 1970, band numbers 796-61848 to 796-61879 inclusive and 796-32001 to 796-32060 inclusive were used. In 1971, band numbers 796-32067 through 796-32200 28 and 796-90901 through 796-90981 were used. Of the 207 bands attached in

1970 and 1971, nine were lost because they were attached before the nestlings' feet were large enough to prevent the band from slipping over the foot. Other bands may have been lost from nestlings outside of the study area, but this is not known.

Reaction to Human Handling

In order to make the measurements of length and weight, it was necessary for the author to handle each of the young birds in the study nests. Each bird reacted individually, but all reacted in a manner characteristic of its age group (Table 3).

Table 3. Reactions to human handling by White-faced Ibis nestlings of various age groups.

Age (days) Reaction

1-4 Squawks when approached; little physical resistance; head held upright; no attempts to escape.

5-8 Less vocal ; cowers in the nest; attempts to hide its head under a wing or chest; some movement when being handled; sits quietly.

8-10 Less cowering, more upright stance; no vocal display; kicks frantically when lifted but is apparently secure when the toes are wrapped around something, even its own wing; sits quietly when placed down.

10- Belligerence increases with age; attempts stabbing or biting attacks with the beak; attempts to escape increase with age. 29

DISCUSSION

A New Record

Breeding colonies of the White-faced Ibis have been reported at many sites in North America and South America. In North America, per- haps the greatest number of breeding ibises is found in Utah. Numerous references to breeding colonies in Box Elder, Davis, Weber, Tooele and

Salt Lake Counties can be found in the Review of the Literature section of this paper. No previous reference has been made to the breeding status of the ibis in Utah County. This paper, then, is the first report of the nesting of the White-faced Ibis on Utah Lake.

Earliest Arrival Dates

The White-faced Ibis arrives at its Utah nesting grounds in the early spring. Ryder (1967) stated that the ibis arrives at Bear River

National Wildlife Refuge in early April. Lockerbie (1944) and Smith

(personal communication) confirmed this by reporting April 11 as the date of the first sighting of the ibis in 1944 and 1968, respectively.

The earliest date of arrival for Utah was reported as March 13, 1955, on

Farmington Bay, Davis Co., by Tanner (1955). Other first sighting dates for Farmington Bay are :March 28 (Barnes, 1943), April 5, (Kotter, 1970), and April 20, (Tainter, 1954). The present study shows April 15 as the date of the first sighting on Utah Lake. This was in accord with the dates found in the literature.

The wide variation in arrival dates was probably due to variations 30

in the annual weather patterns, as implied by Smith (personal communi-

cation). A hard or late winter in Utah would delay the growth of

bulrushes, which are apparently necessary for roosting and nesting in

Utah (Smith, personal communication; Kotter, 1970; Weller, Wingfield and

Low, 1958). There are no references in the literature to an ibis in Utah

roosting or nesting in vegetation other than bulrushes or, occasionally,

cattails. Of course, the lack of proper habitat in Utah could not be known by the birds in their wintering grounds in Mexico or while they

are en route northward, so there must be some form of meteorological

communication, or something similar, which triggers in the birds the

desire to migrate northward at the proper time. Little is known about

the triggering mechanism for migration. Perhaps a study correlating the known arrival dates and the meteorological data for that spring with

information about the growth patterns and physiological needs of both

the habitat vegetation and food sources would give some clue to condi-

tions conducive to the arrival of the ibis.

Blinds

The blind erected on April 30, 1971 (Fig. 3), was set up in the nesting site used in 1970 on the assumption that this would also be the nesting site in 1971. However, the 1971 site was located one mile southeast of the 1970 site, effectively preventing my finding out whether

the birds could become accu3tomed to such a large and strange object.

My first assumption was that the blind had disturbed the birds enough to cause them to find another site, but further observation revealed

that the bulrushes in the 1971 nesting site were at a much more advanced stage of development than those in the old site. When the birds first arrived, they probably chose the stand of bulrushes which was best able 31

to support their weight to serve as a roosting site and this later

became the nesting site (Smith, personal communication).

When visits to the 1970 nesting site where the blind had been

set up showed no signs of either roosting or nesting, it was apparent

that the site had been relocated. Attempts to locate the new nesting

site were conducted from a distance in order to minimize disturbances

to the colony. The author attempted to locate the roosting area by tri-

angulating the landing sites when the birds returned from feeding in the

evening. A large billboard (Fig. 2) approximately midway between the

two interchanges on I-15 served as an observation post for determining

the landing site along a north-south axis. The roof of the car, parked

one-half mile southeast of radio station KOVO, served as the observation

post for the east-west axis. Using these two points for triangulation

should have easily pinpointed the location of the roosting site, had the

birds settled down before darkness set in. However, they usually settled

temporarily in two or three places before settling down for the night.

This final settling was always after dark until the latter part of May when the birds settled down before darkness and the author was able to

complete a triangulation. On May 29, blind #1 was set up (Fig. 3).

A reward for not entering the marsh during the search for the

roosting area was realized when, in days subsequent to setting up the

blind, a number of semi-completed abandoned nests near the work area were observed. This did not appear significant until the completion of

a census of the entire colony on June 12, at which time there could be

seen no semi-completed nests outside of the small area which had been

disturbed. I could possibly have caused a nesting failure, or at least a relocation of the colony, had I searched for the colony by walking

through the marsh. 32

Nests

The White-faced Ibis is apparently opportunistic in its choice

of building materials and in the location of the nest. Palmer (1962)

describes nests being built on the ground in tall marsh vegetation such

as cattails (~) of dry cattail stalks and similar materials. He

also states that if the nest is located in the tops of bushes or small

trees, the nest material is principally sticks and twigs with a green

vegetation lining. He does not give the geographical location for these

types of nests. Davie (1900) describes the nest as "broken bits of dead

tules, supported by and attached to broken and upright stalks of living

ones." Tyler (1933), in writing of the exposure of young to the direct

rays of the sun, said that the nest is fully exposed and usually cut off

from any breeze that might be available.

On Provo Bay, the ibis builds its nest in Scirpus acutus, which

grows to a height of over 2.7m. At the selected site, the ibis bends

the bulrushes toward the center and interweaves them to form the foun-

dation. Smaller pieces are then carried in and woven to form the base

of the nest. Finally, the cup is made of firer, but by no means softer,

pieces of bulrush and occasionally, some grasses or sedges are used,

although the most common material for the entire nest is bulrush. Other materials are used very infrequently. The high and low nests collected

for comparative measurements and faunal analysis should not be considered

as typical for their respective height classes. Further study is needed

to either confirm or refute the differences noted.

Since no clear-cut division into two groups of high and low can

be made, the nests selected for collection and analysis were arbitrarily

chosen because they had been recently vacated and one was chest height 33

and the other thigh height. These two nests (Table 1, #6 and #8) were

different in height by 35.5cm at the first measurement and 59.8cm at

the second. Other nests were lower at the first measurement, but these

had been abandoned for a long time or were occupied at the time of

collection. It was feared that if the nests were long abandoned, the

numbers and kinds of associated invertebrates would be reduced; hence

recently vacated nests were selected.

The change in height of the occupied nests (Table 1) can be

attributed to the presence of the growing young ibises. The weight

supported by each nest changed from approximately 28 grams per egg at

hatching to over 375 grams per bird by the time they left the nest. Also

waste materials from the young birds were accumulating in the base of

the nest adding to its weight.

The unoccupied nests (Table 1) changed height in both up and

down directions. The upward direction would be caused by the supporting

bulrushes which, growing normally, would carry the nest up with them.

The unoccupied nests which decreased in height were apparently too heavy

for the bulrushes upon which they were built, and although the bulrushes

undoubtedly continued to grow, they were not strong enough to lift the

nest higher but in fact were compressed somewhat.

Bent (1926) described the nest height as ranging from floating

on the surface to 12 inches (30.5cm) above the water on nests in Texas.

Willet and Jay (1911) gave an average height of 4 feet (121.9cm) above

the water on San Jacinto Lake, California. Bee and Hutchings (1942)

stated the nests were approximately 22 inches (55.9cm) above the water

at Black slough and Bear River marshes in Utah. Kotter (1970) quoted

Belknap as saying that the ibis nests in Louisiana averaged 3 feet 34

(91.44cm) above the water. The bulrushes in the above references were probably Scirpus acutus, a tall emergent. Kotter (1970) studied the ibis nesting in~- paludosus, a short bulrush which may grow on mud flats with little or no standing water. He found some nests built on the ground in areas where flooding did not occur and upwards of 3 feet

(91.44cm) in height where water depths varied. Subtracting the 61cm water depth from the measurements found in the present study (Table 1) would make these measurements comparable to those of Bee and Hutchings

(1942) for the average height, Bent (1926) for the minimum and Belknap

(in Kotter, 1970) for the maximum, but considerably less than those found by Willet and Jay (1911). Since Kotter's study was conducted in bulrushes with growth characteristics much different from those of s. acutus, a direct comparison of nest heights would only be a reflection of the different types of vegetation, as would be a comparison between these bulrush nests and those described by Palmer (1962) as being con- structed of either cattail stalks or twigs.

The invertebrates collected in the Berlese funnel should not be considered exclusive if they were found in either of the nests examined nor should they be considered general if they were in both nests. The listed are only examples of what may be found in a nest and the list should not be misconstrued as definitive. No other list of this type for the White-faced Ibis has been seen by the author.

Regardless of the nest type, a wet, marsh-type habitat seems to be a prerequisite to nesting and may be considered as the basic habitat type for the nesting of the ibis. Questions concerning certain condi- tions or situations observed within this habitat remain to be answered by further research. Specifically, we may ask the following questions 35 concerning the nesting preferences. Is the choice of specific nesting habitat invariable from year to year, implying ecological isolation?

Are the colonies geographically separated from each other throughout the year so that breeding is strictly intracolonial, giving the possi- bility of genetic isolation? Assuming that the ibises breed in separate colonies but winter together, is there some intermixing between colonies when they separate for their breeding grounds in the spring thereby maintaining a uniform pool throughout its range? Is P. chihi a definite species (A.o.u., 1957), or is it a subspecies off. falcinellus

(Palmer, 1962)? Is the wide variation in choice of nesting habitats an ecological within the species, or is it an adaptability to numerous microhabitats within the general habitat inherent within the species? These questions remain to be resolved by more intensive research.

Spacing of the nests seemed to lack any hint of order. As was true of Kotter' s (1970) findings, spacing varied from very close to very far away, with the density of nests decreasing away from tre center of the colony. Spacing is probably based upon the availability of a stand of bulrushes of sufficient density to support the nest. Since little overt belligerence between birds was noted, this was discounted as a cause for minimum spacing.

Desertion of Nests

Three possible reasons for the abandonment of the nests visible from the two blinds and the ten study nests are: (1) some ibis build nests, lay eggs and abandon the nest; (2) the presence of humans in the nesting colony caused enough disturbance to frighten the nesting birds 36 away; (3) the blind itself was sufficiently disturbing to cause aban- donment.

Kotter (1970) quotes Smith as saying that some ibises may build a nest, lay a clutch and desert the nest, desertion coming because 85 percent of the eggs had soft shells and were crushed. In the eleven nests around tre blinds and in study nests 1, 2, 7, 9, 10, 11, 12, 13,

14, and 15 (Fig. 3), all of which were deserted nests, none had soft- shelled eggs. Kotter (1970) stated that as the laying period progressed, the ibis' attachment for the nest became stronger. As the clutch became larger, the adults allowed him to approach closer to the nest before fleeing, flew less distance away and remained away for a shorter time.

This did not hold true for the Utah Lake ibis. If Kotter's assumption were applicable to Utah Lake ibis, attraction to the nest should have been at its maximum, since 8 of the 10 deserted study nests contained

3 or more eggs,and only 4 of the 11 nests visible from the blinds con- tained fewer than 3 eggs. Whether the adults abandoned the study nests because of the author's intrusion into the study area is not known. If the birds had already abandoned the nests prior to any disturbance by the author, (1) may be true but for reasons different than Smith's.

Observations made from the blinds may clarify this matter. The blinds were left in place, unused, for a few days to allow the birds some acclimation time. On the first full day of observations from blind

4tl, each nest was checked at least once by an adult bird and incubated for a short time. The nests were left unattended for approximately 80 percent of the daylight hours. At dusk, an adult returned to each nest and was undisturbed as I left the blind after dark. On the second day, however, only one bird was observed during the day. This appeared to be acting as a "nurse" bird, hopping from nest to nest and checking the 37 eggs with its beak. This bird incubated four nests during the day. In the evening, only this bird remained and no other birds returned to these nests. On the third day, although birds were seen and heard all through the marsh, none came near these nests, and from that day these nests were not approached by any ibises. At blind #2, one egg was laid after the blind was set up but no attendant adults were ever seen at the nests.

Perhaps all three possibilities are true, at least in part.

Combinations of the three may also be responsible for causing abandon- ment. Further examination revealed evidence for all three possibilities.

Study nests 1, 2, 7, 9, and 10 were all incubated at least one day but not longer than two weeks after being selected as a study nest. When they were abandoned, the nest cup in each was torn up and the eggs partially concealed by the debris. In study nests 11, 12, 13, 14, and

15, an adult was never seen at the nest or leaving the nest and the nest cup was intact in all. These latter five nests could well have been deserted before they were selected as study nests, eliminating the possibility of human disturbance as the causative factor. At blind #2, the egg laid between the time the blind was set up and the time it was first used and the abandonment of the other nests during that same time period indicates that the blind was the major causative factor since human disturbance was minimal during that time. At blind #1, the birds seemed tolerant of the blind but deserted after the blind was occupied, indicating that human disturbance was the cause. These nests were also torn up. It would appear, then, that the causes for desertion are varied and complex, and probably so intertwined that recognition of any one is difficult if not impossible. 38

Clutch Size

The normal clutch size is 3 to 4 eggs (Fig. 11) (Davie, 1900;

Pearson, 1917; Bent, 1926, Palmer, 1962; Smith, personal communication).

Smith (personal communication) mentioned occasionaily seeing five eggs

in a nest. Bent (1926) reported that 5, 6, or even 7 eggs may be found

in a nest. In this study, nests of supernumerary eggs were found both

in and out of the study area. One nest in the study area (Table 1, #21)

contained 5 eggs and one nest near the south edge of the colony contained

6 eggs. Boyle (1922) collected one clutch from Box Elder Co., Utah,

containing 8 eggs. He questioned whether this was a single clutch and

surmised that these were eggs from two females. Evidence that two or more females will lay eggs in the same nest is lacking in the literature.

Perhaps further field observations will shed light on this problem if a means of identifying individual birds can be found.

Average clutch size for this study of 3.17 eggs per nest is, in general, in accord with references in the literature. Bee (1933) collected 18 clutches from Black slough, Salt Lake Co., for an average of 3.6 eggs per clutch. Ryder (1967) estimated that the average clutch

size for Utah should be 2.75 or more. Boyle (1922) collected 9 clutches

from Box Elder Co., giving an average of 4. 3, but this is complicated by the fact that one nest contained 8 eggs. Boyle was not certain if

this represented one clutch or multiple clutches in one nest. The pre-

sence of such a large clutch in such a small sample is very misleading.

Such large clutches are the exception rather_ than the rule. Kotter' s

(1970) figures are questionable because of an error, either in arithmetic or typing. He mentioned that of the 100 marked nests, 84 eventually had eggs laid in them, but in categorizing these nests by the number of eggs 39

Fig. 11. White-faced Ibis nest with three eggs; note pip in upper egg. Eggs are paler blue than actual color . 40

per nest, he gave a total of 83 nests with 262 eggs, not 266, as he noted in the text. If his text statement "40 had 4" were corrected to read "41 had 4", the totals for nests and eggs would be as he stated

them. Whether this was the error is not certain. However, the error had little effect on the results, as there is only .01 difference between his results and mine. Kotter also gave an average for all 100 nests in the study, which was not done in the present study.

Only nests containing eggs were included in the census. Empty nests were not included in the census because (1) if the nest were built and abandoned, somewhat after the manner of Marsh Wrens, the nest was never intended for use as a function of reproduction, or (2) if the nest were in the 4-day interim between completion of construction and the

laying of the first egg, (Kotter, 1970), the nest would have been counted as a "0" in the census and the figures derived would have been misleading if eggs had been laid in the nest after the census had been completed.

For these reasons, then, empty nests were not included in the census.

Other authors must have counted in the same manner; otherwise their average clutch size would have been more like Kotter's (1970) when he used the total number of nests in the sanple, occupied or not, and got an average of 2.66 eggs per clutch.

Egg Measurements

Measurements were made of the longitudinal and transverse axes of the ibis egg. The larger of both measurements were (long"itudinal X

transverse in mm) .56.15 X 40.40, while the smaller measurements were

45.90 X 33.60. The averages of these were 51.40 X 36.75. Variations from these measurements may be found in the literature, but they are 41 small, especially when average measurements are compared. Individually, large and small eggs may be found but the average sizes of large numbers of eggs from single colonies are very similar, even in colonies separ- ated by long distances geographically. Bent (1926) reported extremes of 55 X 38, 46 X 33, with an average of 51.5 X 36.0 for 46 eggs measured in Texas. In Utah, Kotter (1970) gave 58.9 X 39.5 and 46.9 X 34.0 as the extremes, with an average of 52.0 X 36.7 for the 266 eggs in the study nests at Farmington Bay, Utah. Bee (1933) measured 64 eggs, giving

61.5 X 38.8 and 47.8 X 33.2 as extremes and 51.86 X 37.02 as the mean at

Black slough, Salt Lake Co., Utah. In Box Elder Co., Utah, Boyle (1922) recorded 56.5 X 38.1 and 48.8 X 35.5, with an average of 51.97 X 33.47.

Palmer's (1962) all-inclusive average of 51.24 X 35.90 emphasizes the overall uniformity of egg sizes of the White-faced Ibis throughout its

North American range. The only deviation from this nearness of agree- ment is the report of Davie (1900) which gave an average of 48.75 X 33.75, with extremes of 55.0 X 37.25 and 43.25 X 32.25, considerably smaller than the others. Davie's measurements were intended as general for the

White-faced Ibis, but apparently the 50 eggs he measured were from birds which for reasons either physiological or genetic produced smaller eggs than those reported from other parts of the ibis' range; hence, we can- not consider Davie's figures as general for the ibis.

Egg Volumes

Preston (1968), in discussing various means of measuring eggs, argued that measuring all the eggs of a colony produces a bias toward the larger clutches, especially if the measurements are made in an attempt to establish a norm, or average, for a species. He stated that 42 it is not the number of eggs but the number of clutches, or sets, or eggs that is the important consideration. He said that selecting one egg randomly from each of about 20 or more clutches gave results which better represented the species.

In accord with Preston's (1968) findings, then, volumes were calculated for 31 eggs from as many nests, with an average of 36.93cc.

For comparison, volumes were calculated for 28 eggs selected from

Kotter's (1970) list of the 204 eggs which he had weighed and measured

(Table 4). These ~re selected on the basis of being average or near average in the longitudinal or transverse axis. Eight eggs with the average transverse axis (36.7rrn:n) were selected along with 3 eggs having

the average longitudinal axis (52.0rrn:n). In order to enlarge the sample,

I selected the next smaller and larger numbers from the average and recorded all eggs having those dimensions. It was necessary to move two increments from the average longitudinal axis to find sufficient numbers to meet Preston's (1968) suggestions for a minimum number of sets. In the range from 51.8rrn:n to 42.3 (none of the eggs measured 51.1 rrn:n), 8 eggs were found on each side of the average. Remarkable balance may be noted in this selection, even without the 51.lrrn:n increment. Of the 3 eggs with the average longitudinal axis, 2 are identical and the third is smaller. Only 2 of the smaller eggs are in the 51.9mm category, with 6 eggs in the 51. 8mm bracket. This was nearly reversed in the larger categories, with 5 eggs measuring 52.2mm and 3 eggs, 52.3mm. Two duplications occurred, giving a net count of 17 clutches, with an aver- age volume of 38.11cc. Taken by groups, the smallest average volume occurre~ as expected, in the 51.8mm group. However, the next 2 smallest averages were found, in order, in the 52.3mm and 52.2rmn groups. The average, 52.0rrn:n, had the largest average volume. 43

Table 4. Comparison of volumes and weights of White-faced Ibis eggs of various sizes (modified from Kotter, 1970).

a Length Width Volume Weight

51.8 36.2 35. 72 38.7 " 36.4 36.21 37.2 II 36.8 36.90 38.0 II 36.9 37.80 37.6 II 38.0 39.46 41.0 II 38.2 39.75 40.0 51.9 35.9 35.18 35.6 II 39.0 41.54 42.4 52.0 38.2 39.91 40.7 " II II 39.8 II 37.5 38.46 39.1 52.2 35.4 34.40 36.7 II 36.4 36.38 36.3 " 37.0 37.59 39.6 II 37.5 38.61 38.8 " 39.2 43.02 42.8 52.3 36.6 36.83 38.3 " 37.1 37.85 37.4 II 37.9 39.50 40.0 50.1 36.7 35.50 37.4 50.3 If 35.64 36.7 50.7 II 35.92 36.4 51.4 II 36.42 37.3 53.5 It 37.91 38.0 53.8 ii 38.12 36.8 54.8 II 38.83 38.9 55.2 II 39.11 41.4 55.4 " 39.25 40.5

aOverall average volume = 37.91cc. b Overall average weight = 38.66gm. 44

In the other dimension, 9 eggs were found having the average transverse axis of 36.7mm. One of these was found in the same clutch as an egg selected for one of the longitudinal axis groups, but was not the same egg. In attempting to increase the number of eggs in the sample by using the transverse axis measurements of 36.6mm and 36.8mm, I found that of the 16 eggs in these two categories there were 8 duplications, one of which was the same egg selected for the longitudinal axis com- parison and another was actually a triplication, being of the same clutch as an egg from each of the two axis. Therefore, the 9 eggs with the transverse axis measurement of 36.7mm comprise this portion of the sample.

The average volume for these 9 eggs was 37.41cc, giving an overall aver- age for both axes of 37.91cc.

Worth (1940), in attempting to develop an index relating egg volume to incubation time, gave 1.75 cu. in. (29.09cc) as the average volume for eggs of the Glossy Ibis (E_. falcinellus) with an incubation period of 21 days. Worth's average volume is less than the smallest egg found in the present study and nearly 10cc or nearly 25 percent less than the average for f• chihi, yet the incubation period is identical with that reported by Bent (1926), Harkin (1961) and Palmer (1962) and observed by Kotter (1970). The average volume for the present study,

36.93cc, when compared with Worth's chart, gave an incubation period more nearly like that of the Wood (Aix sponsa) at 29 days, or the

Broad-winged (Buteo platypterus) at 24 days. One could be led to believe that P. chihi is a larger bird than f• falcinellus, or at least, that the eggs are such. However, Palmer (1962) classified these two species as subspecies off. falcinellus and, in giving separate measure- ments for the subspecies, showed P. f. falcinellus as having a larger 45 egg than_!:.!• chihi, in direct contradiction to the report of Worth.

Also, Bent (1926) and Palmer (1962) list the incubation period as 21-22 days. Worth's data needs updating to make the table valid, at least for this species.

By holding one of the two dimensions constant and increasing the other, an increase in volume will be noted (Table 4). However, a cor- responding change in weight does not occur, precluding a direct rela- tionship between weight and volume. Romanoff and Romanoff (1949) stated that it is possible to calculate the volume (V) of an egg if the weight

(y) is known, by the equation V = 0.933y, which they further refined to

V = 0.913y for precocial birds and V = 0.959y for altricial birds, such as the ibis. Comparison of the volumes and corresponding weights in

Table 4 shows that an egg of any given volume may weigh less than an egg of a smaller volume, or more than an egg of greater volume. Indeed,

Table 4 shows also that eggs with identical volumes may vary from each other in weight. Hence, Romanoff and Romanoff's formula, which may hold true for some species, is inaccurate for the White-faced Ibis.

As shown in Figs. 12, 13, a change in volume is more closely related to a change in the transverse axis than to a change in the longitudinal axis.

Pipping

The first indication that the ibis eggs were about to hatch was the appearance of a faint network of fine white lines on the smooth, pale greenish-blue shell. This began at the transverse axis and spread toward the poles of the egg. A day or two after the first appearance of the network, a small, cracked hump, or pip, appeared on or near the 41

40 -E ...... E 39 (/)

·- 38 *<{ w (/) 37 er.: LtJ CJ)> 36 z <{ 0::: l- 35

34 31 32 33 3"4 35 36 37 38 39 40 41 42 43 44 45

VOLUME (cc) ..

Fig. 12. Comparison of volume with transverse axis of egg of White-faced Ibis, showing nearly linear relationship.

+" 0, 56

55

54

E 53 -E 52 -en X- <( 51 _, <( 50 z 0 - 49 ::> I- (!)- 48 z 0 _, 47

31 32 33 '34 35 36 37 38 ~9 40 41 42 43 44 45 VOLUME (cc)

-1:-- Fig. 13. Comparison of volume with longitudinal axis of eggs of White-faced Ibis, showing -..J lack of linear relationship. 48 transverse axis. This was the location of the , a calcified enlargement near the tip of the upper mandible. Hatching was usually completed within the next 24 hours. Once the faint reticulation appeared, hatching was almost certain. Only two eggs in the study nests were observed to begin the process without completion. One, in nest #10, was deserted at about the time the reticulation appeared. Another, in nest

#2, proceeded until the egg tooth had emerged and stopped at that point when the nest was abandoned. All of the other eggs in the study nests hatched if the reticulations appeared, or else they never advanced beyond the smooth-shell stage.

Hatching

Hatching success can vary according to the basis for the calcu- lations. By counting all eggs in all the nests and using this total in the calculations, one assumes that all the eggs have an equal chance for hatching. It was obvious from the beginning of this study that 15 of the eggs in the study nests would not hatch since adults were not observed near the nests and the eggs were subject to ambient weather con- ditions. These nests were probably abandoned before they were selected as study nests. This is similar to nests mentioned by Smith (personal communication) as being abandoned as soon as the clutch was completed, but the reasons were different. Those nests mentioned by Smith were abandoned due to soft being crushed when incubated by the adult; those in the present study had no soft eggshells and even handling by the author did not cause any damage to the shell. Obviously, includ- ing these eggs in the total number would give low apparent hatching success figures. However, for comparison purposes, the percentage must 49

be calculated using this figure since Kotter (1970), the only reference with this type of information for the ibis, used the total number of

eggs in his 100 study nests. All but two nests of the 84 in his study hatched at least one egg. The eggs in these two nests were included in

the total number of eggs, giving a success figure of 65.7 percent. In

the present study, using the same basis for a total, i.e., all eggs in

the study nests, hatching success was 45.8 percent. It is obvious that, with the possible exception of the two nests in which no hatching occurred, all the nests in Rotter's study which contained eggs were attended by adult birds. Limiting the total number of eggs to those which were attended by adults for even a short period of time brings

the hatching success of the present study to 57.9 percent, still con- siderably lower than Kotter's figure. Further limiting this to only

those nests in which at least one egg hatched gives a result of 86.8 percent for the 11 nests in the present study compared to 67.5 percent for Kotter 1 s 82 nests. These figures would probably have been much closer together if the samples had been of more comparable sizes.

Variation occurs in the nesting season from year to year and may also occur from colony to colony (Ryder, 1967). Using 21 days as the normal incubation period (Bent, 1926; Harkin, 1961; Palmer, 1962), egg laying on Provo Bay probably began about May 19, slightly later than

Harkin's (1961) estimate of May 20 as the mean clutch completion date.

The nesting season at Farmington Bay in 1969 (Kotter, 1970) began about

May 8, with hatching occurring from May 29 to June 6. In Fig. 14, the three peaks when many birds were hatched on the same day indicates that at least two major egg-laying periods occurred, one on either side of a quiet period from May 29 to June 6. The eggs hatching after June 19 could have been laid by (1) birds renesting after abandoning the first en 6 (!) (!) 5 w LL. 4 0 3 0:: w 2 a)

::> z o.______,.______8 9 10 II 12 13 14 15 16 17 18 L9 20 21 22 2 3 24 25 26 27 DATE

Fig. 14. Distribution of egg hatching from June 8-27, 1971.

Lil 0 51 nest, or (2) birds which arrived and nested later than the first group.

Measurements of the Young

Four measurements were made on the nestlings for comparison of the areas in which the most rapid growth seemed to take place. Linear measurements of the beak, tarsometatarsus and a feather were made daily on each bird along with the weighing (Figs. 7, 8, 9, 10).

At hatching, obviously, a bird has weight, a bill, and legs.

These three parameters, then, were measured from the day of hatching.

Feathers were measurable on the fourth day when the sheaths erupted from the on the earliest birds. Others erupted as late as the eighth day.

Superimposing the graphs showing linear increase (Fig. 15) gives a comparison of the growth rates of these parts of the nestling's body.

The beak increases most rapidly at first, but is overtaken by the tarso- metatarsus at about the same time the begin emerging from the skin. From this point in time, the order of increase reverses, with the feather growing most rapidly, the tarsornetatarsus next and the beak becoming the slowest growing of the three. The average daily growth rate for the three reflects this (Fig. 15). Comparison of Fig. 7 with Figs.

8 and 9 shows a plateau forming at day 9 for all but the feather. When rapid growth is resumed by these two, the feather almost triples its daily rate, going from 4.75mm per day to 13mm. This is probably a re- flection of a metabolic redirection of energy.

Data after the 15th day should be considered unreliable because the number of birds measured was small and the same bird was rarely measured on consecutive days. 52

120 l = Feather

110 2= Torsometata rsus 3= Beak

100

90

80

-E 70 -E r 60 I- (.!) z 3 w 50 _J

40

30

20

10

o.______I 2 3 4 5 6 7 8 9 IO I I 12 13 14 15 16 17 18 19 20 21 D A Y

Fig. 15. Direct comparison of the linear measurements of beak, feather, and tarsometatarsus of nestling White-faced Ibises. 53

Measurements of specimens of adult ibises in the B.Y.U. Life

Sciences Museum indicate that the young ibises may grow to have a tarsal length of 98rrnn, a beak length of 132mm, both well within the range given by Palmer (1962), and a feather length of approximately 175mm.

These dimensions should be attained by the end of the first year (Palmer,

1962).

Kotter's (1970) thesis is the only one giving information on the weights of the nestlings. He was able to conduct this phase of the study for only four days, during which his subjects were gradually depleted by what he surmised as Franklin Gull incited by the markers which he placed on the ibis nestlings' legs. By the fifth day, none of his subjects remained. The weights he was able to record, how- ever, were within the ranges shown in Fig. 6.

Development of the Young

While inside the egg, the ibis's was pointed toward the large end of the egg and the base of the neck was at the small end. The neck was bent with the lower part of the head resting on the stomach.

This positioned the egg tooth near the transverse axis. At hatching, the egg tooth was used to pierce the shell, after which by squirming and pushing, the ibis was able to push the shell parts away from each other and work its way out into the nest. Shell parts were apparently disposed of by the adults as none were observed around the nests. The new nestling was covered by a soft, fluffy black down, which offered little protection to the pink skin. The eyes were semi-closed and the tarsi were pink, with faint hints of black along the posterior side. The beak was about 15mm long, with three black bands separating two pink areas. The birds were of flying age before the pink areas were covered by the black. On some, 54 a slight reddish fringe could be seen on the pinkish of the head.

On the first and second day, the birds could be handled with little apparent fright on their part.

On the second day, a patch of white down which nearly covered

the crown appeared. The reddish down seen on the first day may have been covered with residue from the inside of the egg; however, some birds which totally lacked the red fringe on the first day were seen with the white down on the second day, indicating that at least in some cases, the white down was a growth which occurred between the first and second days.

Some hatchlings also developed a reddish patch of down with a white fringe. The eyes were fully open. A visible increase had occurred in body dimensions; hence, one was able to plainly distinguish between nestlings if they were one day apart in age, and the marking which caused

Kotter (1970) to lose his subjects is unnecessary. The posterior half of the tarsus was now pinkish-black. The middle band on the beak was expanding away from center.

Little physical change, save an increase in size, was to be noted on the third day. However, a change in behavior could be detected when one approached the nest. The young sat up in the nest and squawked hoarsely when alarmed. Little resistance was offered when the birds were handled. The legs were very weak at this age and little movement was noted in the nest. The black on the tarsus had increased until about 75 percent was pinkish-black (Fig. 16).

The most notable change occurring on about the fourth day was

the emergence of feather sheaths on the alar and capital tracts. The white down on the crown was beginning to diminish. On a few of the birds, a white spot appeared on the upper throat. The legs had gained 55

Fig. 16. White-faced Ibis nest containing (counter clockwise from egg) pipped egg, two- and three-day old nestlings. Note cowering posture of nestlings. 56

a little strength and the birds were able to move around the nest a

little but they were not strong enough to support the body. The tarsus

was nearly covered with black, but much pink still showed through.

Behavior was unchanged.

On about the firth day, the birds were able to lift their bodies

off the nest slightly, but were as yet unable to walk. The tarsi were

almost completely black, with little pink showing. The white down on

the head was almost gone in most birds but remained in some. The egg

tooth had disappeared. A change in behavior was noted. Upon being

alarmed, the nestling attempted to hide its head in some way, by pushing

it under its own stomach or under a sibling. The squawks were fewer and

of less volume. Since it now had a little strength in its legs, the

nestling kicked feebly when lifted from the nest. This type of behavior

would continue until about the eighth day.

A #6 band from the U.S. Bureau of Sport Fisheries and Wildlife may be placed on the leg after about the sixth day. The tarsus was com-

pletely black with little, if any, pink showing. The tarsal coloration must be at this stage before the knuckles are large enough to prevent

the band from slipping off. The white crown had almost disappeared.

Sheaths were more numerous but were still present only on the alar and

capital tracts.

By the seventh day, the nestling was able to stand in a slightly

crouched position. The tarsus was completely black and remained so until

adult began to appear (Palmer, 1962). Very few white crowns, if

any, remained at this stage. Feather sheaths were beginning to break and

shafts appeared from the ends of the sheaths as a short, dark-green

tassel.

Behavior again changed on about the eighth day. The birds were 57 able to stand upright and walk for very short distances. In attempting to escape, the young took only a few steps before collapsing. When lifted from the nest, the young kicked frantically until their toes grasped something, even if it was their own wing, at which time they ceasedstruggling. Cowering in the nest or attempts to hide the head were not noted from this time on. The birds uttered no noise at this time and made no defensive movements when handled. The primary and secondary wing feathers began to emerge and the postnatal molt was clearly evidenced by the thinning black down. Small, black pin feathers began to appear on the body.

Most of the young were able to wander short distances from the nest beginning about the ninth day. If they did not leave the nest proper, they were at least able to stand upright and walk on the edge of the nest. The skin was somewhat darker. The beak had more than doubled in length and the birds had increased nearly 8 times in weight. The neck had lengthened, giving a very awkward, unbalanced look to the bird .•

I ts posture and dexterity while walking added nothing to its image of grace.

At ten days, another slight change in behavior occurred. Upon being approached, the nestling stood on the opposite side of the nest, facing the intruder. It then bowed its wings out about an inch from the body, as if trying to intimidate. From this age on, belligerence increased and defense became more active. By belligerent defense, I mean only that the birds occasionally attempted to bite or stab with the beak, but the efforts were feeble and accompanied by little strength, resulting in only slight discomfort. Escape was the prime defense and the birds would gradually become more adept at moving through the bul- rushes. 58

By the twelfth day, it was rare to find a nestling in the nest proper, but they were usually within a few feet of the nest in the bul- rushes and moved slowly enough to be caught. The wing feathers were about 45mm long at this stage, with about 11mm of dark, metallic green extending from the sheath. The body feathers were still quite bristly, with little vane showing. The beak had begun to show a little decurving, which was evident only upon close examination.

From this point in time, the birds were absent more and more from the nest. Strength and agility had developed so much that it was difficult to capture them if they were outside the nest. It was also for this reason that the information later than the 15th day in Figures

7, 8, 9, 10 and 15 must be questioned as being representative of birds of that age since the older birds measured were the weaker, less-devel- oped ones who could not escape. Graphs depicting a sample containing all birds over 15 days of age would probably be characterized by rapid in- creases on the upper end which probably would not taper until adulthood was nearly reached. As it is, however, the only representatives of this age group are those that were unable to escape.

Age at Leaving Nest

Leaving the nest will be defined herein as being of sufficient distance from the nest as to be unidentifiable with that nest. As stated earlier, the birds began v,andering outside the nest at about 8 days of age, but these birds only traveled about 5 feet from the nest and were thus identifiable with a specific nest. "Sufficient distance" means, then, that the birds were out of sight and could not be identi- fied but were not necessarily out of hearing range. 59

The age at which the young birds left the nest varied consider- ably, but was usually related to the bird's order in the sequence of hatching. Those hatched early in the clutch seldom left the nest before reaching 14 days of age while those hatched later sometimes left as early as 9 days. The example set by the older birds probably influenced the younger birds to leave earlier, even though they were not as physically developed as their older siblings were when they first left the nest.

The physical disposition of the nest itself at the time of leav- ing also influenced the age at which birds left the nest. A comparison of nests of different heights will illustrate this. Nest #17 was pro- bably about 54cm above the water when the birds left in the first week in July (Table 1). The three nestlings were over 20 days of age when they left. Nest #18 was about 30cm aoove the water when the birds left at 14, 16 and 11 days of age. (The latter bird probably was following the example of his elders.) By contrast, nest 4fo21had settled until the cup was only about 15cm above water. The oldest bird to leave this nest was 12 days old, and his siblings followed on the same day, the youngest being but 9 days old. Apparently, then, the proximity of the nests to the previous year's bulrushes, which lie horizontally across the water, is a strong influence in detennining when the birds will leave the nest.

Flight

The first flights of birds of the year were observed on July 4,

1971. Two birds were seen to rise to a height of about 4.5m and glide directly to a spot about 6m away. These were the only flights observed all day. On July 5th, ten such flights were seen, all direct glides for short distances. The first maneuver was seen on July 7th, when a bird 60 rose into the air, flapped rather than glided, and when beginning to land, rose, changed direction, and flew to another spot and landed. This flight was very slow and clumsy, accompanied by much frantic wing-beating.

After these incidents, however, many birds were seen flying skillfully for long distances over the marsh.

It is not difficult to differentiate between flying adults and young at any distance at which either color or silhouette can be seen.

The body of the adult is colored brownish-red to chestnut (Cory, 1899;

Forbush and May, 1939; Palmer, 1962) with metallic green wings and tail feathers. Though the young shares the wing and tail coloration, its body is a dull blackish-gray. Bill shape is also different, that of the adults being deeply decurved and long, while that of the young is visibly shorter and nearly straight with little decurving.

The age at which birds first fly was, according to Kotter (1970), during the fourth week of life. My only observation of anything resembl- ing flight by any bird whose age I knew occurred when a 23-day-old bird jumped off the scales and glided about 2.5m.

Food Items of the Young

A table (Table 5) in Ryder's (1967) paper quoted a list of food items compiled by Petersen in 1953 which was based on examination of 209 stomachs of ibises, 52 of which were immatures feeding with adults. He listed 11 orders of which had served as food for the ibises in northern Utah at some time over a three-year period (1951-1953). Four of these orders (listed in descending order of occurrence), Coleoptera,

Diptera, Hemiptera and Odonata, accounted for 97 percent of the insect portion of the total list. Earthworms accounted for nearly 40 percent of 61

Table 5. Numbers of food items found in 209 White-faced Ibis stomachs collected in northern Utah, 1951-1953 (Petersen, 1953, IN Ryder, 1967).

Period of collection (No.*of Stomachs in Parentheses ) May-June July-Aug Sept-Oct Food Item (76) (34) (99) Totals

Insects 1632 668 2238 4538 Orthoptera 0 11 11 22 Ephemerida 0 17 0 17 Odonata 15 61 407 483 Plecoptera 0 0 1 1 Homoptera 0 1 0 1 Hemiptera l 22 736 759 Coleoptera 1242 87 749 2078 Trichoptera 0 4 0 4 62 9 15 86 Diptera 302 456 319 1077 10 0 0 10 Earthworms 1482 406 1152 3040 Leeches 56 97 27 180 Snails 7.3 27 .3 103 l 2 13 16 Crayfish 0 0 1 1 Fish (carp) 0 1 0 1 Sma11 marrnna1 , bones 0 .L 3 4 Weed 0 1 4 4

*Fifty-two of the 209 stomachs were from immature ibises feeding with adults. 62

the total food items consumed by these ibises. Comparison of these results with Table 2 shows that only two insect orders, Coleoptera, and

Diptera, and spiders and snails, both minor items in Petersen's findings, were the only food items found in the regurgitant of nestlings in Utah

Valley. Some of the possible explanations for this difference are:

(1) earthworms do not exist in Utah Valley; (2) the adult ibises eat one

type of food themselves and give a different type to the nestlings;

(3) because of differential rates of digestion, only certain types of food remain for the young if the adults have to travel very far after obtaining the food; and (4) the food given the young is what is available near the nesting colony. Anyone who is at all familiar with Utah Valley recognizes immediately that (1) is ludicrous. The actual explanation is more likely a combination of (2), (3) and (4) than a single answer. Soft- bodied food items obtained at great distances from the colony will, obvi- ously be digested before the adult can return to the nest. Slower digesting foods will be all that remain for the young. The most blatant disadvantage here is that if the food is slow digesting, the young may starve to death with a full stomach because the food does not digest fast enough to supply energy for their high metabolic rate. Certain high- energy foods may be fed exclusively to the young, with the adults having an entirely different or at least more expansive diet. Further research into the food habits, especially specific food items and their geographi- cal locations from the colony, would shed light on this subject.

Knowlton and Harmston (1943) collected one ibis near Kanesville,

Utah, in July, 1940, which had eaten two adult grasshoppers and a field cricket. Table 5 shows that Orthopterans increase in numbers as a food item during the summer but are not of great importance. 63

Ectoparasites

Fmerson (1962) noted that the Mallophaga found on P. falcinellus and P. chihi were not distinguishable from each and listed the same species as inhabiting both hosts. He listed Ardeicola rhaphidius

(Nitzsch, 1866~ Ciconiphilus blagoweschenskii (Dubinin, 1938),

Colpocephalum leptopygos (Nitzsch, 1874), Ibidoecus bisignatus (Nitzsch,

1866), and Plegadiphilus plegadis (Dubinin, 1938) as the five species which could be possible parasites of these two species. Elbel (personal communication) identified all Mallophaga collected by the author from P. chihi as the last listed species. In addition, three flies were found but these have not been identified.

Wintering Grounds

There is general agreement that Mexico is the principal winter- ing ground for the ibises from Utah (Bent, 1926; Palmer, 1962; Ryder,

1967). Ibises have also been known to winter in the Los Banos and

Imperial Valley areas of California, near Yuma and Tombstone, Arizona

(Ryder, 1967), and in Louisiana (Bent, 1926; Ryder, 1967).

Table 6 lists the states in Mexico where ibises banded in Utah have been recovered (Josey, 1893; Bailey, 1906; Lamb, 1910; Phillips,

1911; Swarth, 1933; Bailey and Conover, 1935; Lea and Edwards, 1950;

Ryder, 1967). Ibises have been observed at other places in Mexico, but

these birds have not been coliec ted and their place of origin in North

America is not known. Such a place is San Luis Potosi (Davis, 1952), where only a few have been seen occasionally, giving the impression that perhaps these are stragglers from the surrounding states of Zacatecas,

Guanajuato,Queretaro or Tamaulipas (Fig. 17). 64

Table 6. Places of recovery of White-faced Ibises banded in Utah as nestlings.

Number of Places of Recovery Recoveries Percent

Arizona 1 0.9

California 2 1.8

Texas 1 0.9

Utah 5 4.5

Mexico (Total recoveries 102, 92.0 percent) Durango 1 0.9 Guanajuato 11 9.9 Guerrero 6 5.4 Jalisco 27 24.3 Mexico, D. F. 1 0.9 Michoacan 30 27.0 Nayarit 12 10.8 Queretaro 1 0.9 Sinaloa 6 5.4 Sonora 1 0.9 Tamaulipas 2 1.8 Vera Cruz 3 2.7 Zacatecas 1 0.9 111 100.0 65

CHIHUAHUA

LEGEND

M:MORE LOS A=AGUASCALIENTES HI D;H ID AL G 0 GUANA=GUANAJUATO QUERE=QUERE TARO

I I// =States reporting recoveries or slghHng1

Fig. 17. States in Mexico where White-faced Ibises have been recovered or seen. 66

The reported wintering grounds extend along both coasts and across the central highlands of Mexico for the ibises banded in Utah

(Fig. 17), strengthening the possibility that some birds from one nesting area will go to a different nesting area when they return north in the spring.

Banding

The first ibises banded in Utah were those processed by Alexander

Wetmore in 1916, when he banded 104 birds. From that year to 1970, another 3158 birds had been banded (Ryder, 1967; Smith, personal connnuni- cation) and 122 bands had been recovered, mostly from Mexico (Table 6;

Fig. 16), although some have been reported from California (Wetmore,

1923), Texas and Arizona (Ryder, 1967). Recoveries have also been made near the spot where the banding occurred. Ryder (1967) stated that some philopatry to the banding site is evident. One ibis was found near the banding site four years later, and another was recovered five years after banding some 16km from the banding site.

Birds have also been banded in California, Oregon, Kansas (Ryder,

1967), and Colorado (Ryder and Robinson, 1971), but in lesser numbers than in Utah and few recoveries have been reported.

During the present study, 207 bands were used and of these 198 are believed to have remained on the birds. One return has been reported, that being from a bird banded in 1970. The recovery was made in Novem- ber, 1970, at a place called Desconocido, Michoacan, Mexico (Fig. 17). 67

SUMMARY

The White-faced Ibis (Plegadis chihi) nests on Provo Bay, Utah

Co., Utah. Earliest arrival was April 15, 1971.

Nests are built in large, dense stands of hardstem bulrush

(Scirpus acutus). Nest height ranged from water level to 205cm.

Settling occurred in active nests while inactive nests showed little change in height. Variation could be seen in size of nesting materials from nests of different heights. Some variation was noted in the in- associated with nests of different heights. Nest spacing depended upon density of bulrushes rather than proximity of neighbors.

Desertion of some nests occurred because of (1) physiological reasons, (2) human disturbance, or (3) the presence of blinds or a combination of the three.

Average clutch size was 3.17, ranging from 1 to 6. Average egg length and width was 51.40mm X 36.75mm. Average volume was 36.93cc.

Hatching occurred from June 8-27, 1971, with overall success of

45.8 percent. Two distinct hatching periods were noted.

In 21 days, beak increased from 15mm to 50mm, tarsometatarsus from 15mm to 65mm, feather from 0mm to 120mm, and weight from 28gm to over 375gm.

Age of nestlings can be estimated by observing behavior, size and appearance. Bureau of Sport Fisheries and Wildlife bands may be attached after the sixth day.

Age at leaving the nest depended upon hatching order, sibling 68 influence and height of the nest. Youngest was 9 days.

Flight was observed on July 4, during the fourth week of life.

Flying adults and young can be differentiated by body coloration or size and shape of beak.

Food items of nestlings differ from those of free-feeding young.

The , Plegadiphilus plegadis, and three unidentified flies were the only ectoparasites found.

The White-faced Ibises winter in the highlands and along the coasts of central Mexico. Of the 207 bands used in 1970-71, one has been recovered from Michoacan, Mexico. 69

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ON UTAH L

Kenichi David Kaneko

Department of Zoology

M.S. Degree, May 1972

ABSTRACT

Information on the nesting of the White-faced Ibis (Plegadis chihi) in Utah County is presented for the first time. Nests built in hardstem bulrush (Sciprus acutus) settled £re an average height of 120.8cm on June 9 to 93.6cm on June 27, 1971. Nest spacing ranged from 2m to 9m, averaging 4.6m. Invertebrates of the class Arachnida and the insect orders Coleoptera, Homoptera, Lepidoptera, and Thysanoptera were collected in a Berlese funnel. Average clutch size was 3.17. Egg length and width averaged 51.40m X 36.75mm. Average volume was 36.93cc. In 21 study nests, 45.8 percent of the eggs hatched, beginning on June 8 and ending on June 27. The young weighed approximately 26g at hatching, with tarsometatarsus and bill each 15mm long. These increased to 400gm, 70m, and 45m, respectively, in 15 days. Feather shaft had grow to over 100mm. Major food items of the nestlings were larvae of the insect families Dytiscidae, Hydrophylidae (0. Coleoptera) and Stratiomyidae (0. Diptera). Ectoparasites collected were a louse, Plegadiphilus plegadis, and three unidentified flies.

COMITTEE APPROVAL: V I T A

Kenichi David Kaneko