The CondorX6:30-35 0 The Cooper Ornithological Society I984

NESTING AND FEEDING HABITS OF BROWN-CHESTED MARTINS IN RELATION TO WEATHER CONDITIONS

ANGELA K. TURNER

ABSTRACT. -Brown-chested Martins (Phaeoprognetaperu) at Guanare, Vene- zuela, have a clutch size of 4.0 + 0.2 (SE) eggs,smaller than that reported for the ( subis),a temperate .The eggsare incubated for 62.4% of the daylight hours; incubation periods are longer at low ambient tem- peratures. Nestling Brown-chested Martins do not lose weight near fledging; the growth rate constant is 0.284. On a biomass basis, Brown-chested Martins bring more dragonflies to the nest than reported for Purple Martins; relatively more dragonflies are brought as the nestlings grow. Cool, wet, and cloudy weather reduces feeding activity and the rate at which food is gathered by the tropical martin, as has been reported for the temperate species.

Among temperate hirundines, such as Purple Guanare along the main road into the town. I Martins (Progne subis),Common House-Mar- found 22 nest-sites at or near eight bridges, tins (Deli&on urbica), and Barn (Hi- although only 12 nests were accessible.The rundo rustica), bad weather and food scarcity martins fed close to the nest-sites (within reduce the frequency of feeding visits to the roughly 1 km of them) over marsh, grassland, brood and the growth rate and survival of nest- and natural savanna devoted to cattle grazing. lings (Finlay 197 la, Rheinwald 197 1, Bryant The dominant plantswere herbaceouswith few 1975, Turner 1980). Little is known, however, trees,which were mostly under 20 m high. The about the effects of weather on related aerial ground was partially flooded in the wet season. feedersin the tropics where, in contrast to high Small areas of gallery forest extended along latitude sites(e.g., Finlay 197 la), cold weather stretchesof the rivers, but I never saw martins is not usually experienced during the breeding feeding there. season(for example, Ricklefs 197 1). Tropical I monitored the nest attendance of incubat- hirundines, however, feed less during heavy ing martins (sex unknown) at two nests (for rainfall and hot weather (Moreau 1939, Rick- eight l-h periods over two days at one nest lefs 197 1). and 18 1-h periods over seven days at the oth- My purposewas to seehow the breeding and er) and the feeding activity of adults at two feeding ecology of a hirundine is affected by other nests (one with three nestlings-for 25 variations in weather and feeding conditions 1-h periods over eight days-and a secondwith in an area of high ambient temperature. In my four nestlings-for 24 1-h periods over 10 study, the ambient temperature varied from days). Observations began when both broods 23 to 35°C whereas in Finlay’s (1971a) for were seven days old and ended when they were example, it ranged from 2 to 24°C. In this pa- 23 days old. Broods were aged by comparison per, I describethe breeding and feeding habits with weights and wing-lengths of chicks of of Brown-chested Martins (Phaeoprognetap- known age in another nest that was checked era), and compare them with published in- daily. formation concerning Purple Martins, giving I determined what the ate from the particular attention to the effects of weather remains (wings) of prey in droppings under a and feeding conditions. perch and in three nests.Although this method has been used in other studies of hirundines STUDY AREA AND METHODS (Bryant 1973, Waugh 1979) it was not reliable I studied Brown-chested Martins at Guanare, for determining the size of dietary items such Venezuela (9”2’N, 69”44’W, elev. 183 m) from as Lepidoptera and Odonata, because only 12 April to 7 June 198 1. The mean annual fragments of their wings remained. Hence, temperature there is 28.2”C and the annual these groups are probably under-represented rainfall is 1,465 mm. The dry seasonlasts from in my data. I also obtained food bolusesfrom November to the end of March, although some collared nestlingsin two nests (not otherwise rain falls in every month. The peak of the wet usedfor feeding studies).One brood was 7 days seasonis in July (Gonzalez 1948). and the other 11 days old when bolus collec- My study sites were bridges over streams tion began;both were 23 days old when it end- and rivers roughly l-20 km southwest of ed. Collars were left in place for 24 2-h periods BROWN-CHESTED MARTINS 3 1 over 16 days. Walsh (1978) noted that small items slipped past the collar on Purple Martins more than 21 days old, but I saw no evidence of this in my study. Boluses were collected mainly in dry weather; hence, the droppings 50- may represent the overall diet of the martins better than the boluses.In order to determine m _ how much food was brought to a chick per bm unit time, I measured the time taken for the z parent to collect each bolus. E 30- I observed feeding martins on 18 days for periods of 5-l 0 min each (60 periods between 4 07:00-l l:OO, 63 between 11:30-15:00, 74 be- I o” tween 15:30-l 9:00) and recorded the habitat : and foragingheight of the birds asfollows: over 101 0; 0. PO open ground, waterside vegetation, water, or . near trees; below 5 m, 5-50 m, or above 50 , 4 12 20 28 m. I also measured food abundance at these AGE, DAYS feeding sites using a fine mesh (< 1 mm) hand FIGURE 1. Growth curves for three speciesof hirun- net to sample flying (80 samples over dines: open circles,Purple Martin (n = 11; Allen and Nice 23 days): 50 strokes through the air 0.1-2 m 1952);closed circles, Gray-breasted Martin (n = 11; C. T. above ground per sample. To estimate the den- Collins, unpubl.); triangles,Brown-chested Martin (n = 3; sity of rapidly flying insects, such as dragon- this study); horizontal bars, adult weights (Finlay 197la, flies, I set up 14 100-m transectsat the same ffrench 1976, this study). sites and counted the number of flying Odo- nata within 2 m of them over a period of 3 min. 26 h of observation) of the 12 daylight hours At the beginningof each observation period, daily. The attentivenessof the incubating par- I noted the ambient temperature in the shade ent was negatively correlated with T, (r = (T,) and sunlight (T,), windstrength, rainfall -0.57, P < 0.01, 24 df). Incubation periods intensity (both rated on a scale of 1 to 5) and (between successivebouts of feeding) were 2- cloud cover. The latter was rated on a scaleof 25 min in dry (n = 29) and 2-54 min in wet 1 to 7: 1, clear sky; 2, > 0 5 25% white cloud; (n = 39) weather, but over 50% of them lasted 3, > 25 _( 50% white cloud; 4, > 50 I 75% 2- 12 min (median = 11 min). Feeding periods whitecloud; 5, > 75 I 100%whitec1oud;6, i were generally shorter, 60% being less than 8 75% grey cloud; 7, > 75% grey cloud. Values min long (median = 7 min, range l-l 8 min, of 6 or 7 occurred immediately before, during, IZ = 73). The longest period that a martin was or after it rained and such conditions are here- away from its nest was during very heavy rain. after referred to as “wet’.‘;. values between 1 Nestlings in one nest reached a peak weight and 5 denote “dry” condttions. of 36.5 k 0.61 g (n = 3, Fig. 1) at about 20 Numbers throughout the text are means + days of age; the growth rate constant, K, was 1 SE. 0.284 days-’ (calculated from Ricklefs’ [ 19671 graphical method). They came to the entrance RESULTS of the nest-hole to beg for food on day 18 and left the nest at approximately four weeks of BREEDING BIOLOGY age. Fledging successwas 7 1% ( 10 of 14 nest- I found 2 nests in dead trees and 20 in holes lings fledged from six nests). in bridges. Five bridges had a single nest, two had three nests and only one (with 16 appar- FEEDING ECOLOGY ently suitable holes) had four active nests. On a numerical basis, Isoptera were the main Adults frequently fought at entrancesto holes constitutent of the adult martins’ diet, fol- when more than one nest was present at a spe- lowed by Hymenoptera and Diptera (Table 1). cific site. The mean wing-length of the food items was The mean clutch size was 4.0 ? 0.2 eggs 8.4 * 0.1 mm (n = 358). Termites and ants (range 3-5, y1 = 10). Six clutches were de- were caught mainly in wet weather and also stroyed by predators or floods; in the other formed a higher proportion of items in the four, 7 of 14 eggshatched. droppings than in the boluses. (Table 2). The The incubation period was 14-15 days. I composition of the boluses indicates that the saw only one member of each pair incubating. chicks’ diet consistedof (1) significantly (P < The eggswere covered for 62.4 * 2.6% (n = 0.001) smaller insets in wet (48.1 f 6.6 mg, 32 ANGELA K. TURNER

TABLE 1. Percentoccurrence (by numbers)ofinsect taxa TABLE 3. Correlations between the feeding ecology of in the diet of adult Purple and Brown-chestedmartins. Brown-chestedMartins, abundance,and weather.

Brown-chested Ambient PUIpk PUIpk MZU-tlll’ telIlpWa- TaXOn Martin’ Martinb (n = 389) twe in Cloud Dependent variable sunhEht P cover P n Isoptera 0 0 62.5 Orthoptera 1.1 trace 0 Meals h-l nest- Odonata 15.1 o-1 6.7d ling-’ 0.42 0.01 -0.32 0.05 49” Hemiptera 14.6 2-28 1.6 Bolus dry Lepidoptera 9.4 o-14 1.3* weight, mg 0.16 N.S. -0.14 N.S. 24 Diptera 16.1 3-20 10.8 Bolus collection Hymenoptera 23.0 2-35 15.2 time, min -0.85 0.001 0.73 0.001 24’ Coleoatera 12.5 32-68 2.1 Food-gathering rate, mg mini 0.75 0.001 -0.66 0.001 24’ a From gizzards (Beal 19 18). b From gizzards (Johnston 1967). Dragonfly num- = From droppings (this study). bers along d Probably underestimated since these were fragmented in the droppings. transects 0.94 0.001 -0.83 0.001 14 Log,, dry weight of net samples 0.39 0.001 -0.23 0.05 n = 56 insects) than in dry (103.2 * 3.3 mg, 80 y1= 167 insects) weather, and (2) fewer dra- - The number of l- or 2-h periods Over which measurements were made. gonflies when it was wet (36% vs. 63% in wet and dry weather, respectively, x2 = 6.43, P < 0.05). Diptera, Hymenoptera, and small Lep- quickly in warm and dry than in cool and wet idoptera were the major food items in their weather (Table 4, Fig. 2). In this context, the first two to three weeks. Throughout the nest- number of dragonflies and the size of the net ling period, the proportion of dragonflies in sampleswere both correlated with T, and cloud the diet increasedand in dry weather was pos- cover (Table 3). itively correlated with nestling age (r = 0.66, In dry weather, martins fed mainly at low P < 0.05, 9 df). The mean dry weight of prey and medium heightsover watersidevegetation items in the boluseswas 89.0 * 3.4 mg (n = and around trees, but in wet weather they fed 223). more at medium heights (Table 5). Each nestling was fed on average 2.82 f DISCUSSION 0.33 times per hour (n = 24 h of observation) in a brood of three and 2.88 k 0.24 times per BREEDING BIOLOGY hour (n = 25 h of observation) in a brood of Purple Martins in North America usually nest four. In dry weather, nestlings in the latter in (artificially) large groups in martin houses, brood were fed more frequently as they grew within which each male maintains a territory (r = 0.62, P < 0.01, 15 df); the same was not (Brown 1979). Brown-chestedMartins are ter- true for the brood of three (Y = 0.18, 16 df). ritorial, but nest singly or in small groups in Feeding frequency was correlated with T, and natural cavities;in Argentina, for example, they cloud cover (Table 3). During very heavy rain, use old furnariid and termite nests (Hudson the parents ceasedfeeding the nestlings. 1920). Gray-breasted (Progne chalybea), The dry weight of food boluses(overall mean Southern(Galapagos) (P. &guns modesta),and 133.4 -t 2.9 mg, yt = 149) was not correlated Caribbean (P. duminicensis)martins also nest with the weather, but the time taken to collect in crevicesamong rocks or in man-made struc- them was (Table 3): food was gathered more tures(Hartley 19 17, Hudson 1920, Beebe 1924, ffrench 1976). TABLE 2. Percentoccurrence (by numbers)of insecttaxa In common with many generaof birds (Lack in the droppingsand food bolusesofnestling Brown-chest- 1947), tropical and insular speciesof Progne ed Martins. and Phaeoprognehave smaller clutches than their temperate counterparts.For example, the Droppings B0llJses TaXOn (n= 115) (n = 223) Purple Martin has a clutch of 4.8 eggsin Al- berta (Finlay 1971b), 4.9 in Michigan (Allen Isoptera 43.5 8.5 and Nice 1952), and 4.6 in Texas (Brown 1978) Odonata 15.7 54.7 Hemiptera 0 0.4 the range being three to eight eggs.In contrast, Lepidoptera 11.3 22.9 the clutch size of the is only Diptera: 4.3 6.3 two in Tobago and up to six elsewhere in the Brachycera 2.6 1.3 West Indies (ffrench 1976); Gray-breasted Syrphidae 0.9 4.9 Calypterae 0.9 0 Martins produce two to five eggsin northern Hymenoptera: 25.2 7.2 South America (Hartley 19 17, ffrench 1976, Formicoidea 11.3 0.4 Collins, unpubl.) and five in Argentina (Hud- Aculeata 3.5 6.7 son 1920); the Brown-chested Martin, four BROWN-CHESTED MARTINS 33

TABLE 4. Differences in the feeding ecology of Brown-chested Martins in wet and dry weather. Values in the table are means f SE (n) for the number of l- or 2-h periods over which observationswere made.

Variable Dry weather Wet weather P

Meals h-l nestling-l 3.3 + 1.3 (35) 1.7 + 1.1 (14) 0.00 1 Bolus dry weight, mg 129.6 f 20.4 (16) 118.5 f 34.3 (8) N.S. Bolus collection time, min 4.3 k 1.2 (16) 9.1 f 2.7 (8) 0.00 1 Food-gatheringrate, mg min-I 30.7 f 11.8 (16) 14.2 f 4.7 (8) 0.001

(Hudson 1920, this study); and the Southern chestedMartins (82%) than has been reported Martin on the GalapagosIslands only 1.9 eggs for Purple Martins (8% lost, 4% infertile; Brown (Beebe 1924). 1978). Nest failures are common, however, in Incubation periods are similar among the tropical altricial species(Ricklefs 1969.) members of this group: 15-l 8 days for Purple Nestling Purple Martins gain weight until and Gray-breasted martins (Hartley 19 17, Al- they exceed the average adult weight (Fig. 1) len and Nice 1952, Finlay 1971b), and 14-15 before diminishing as water is lost from ma- days for the Brown-chested form in my study. turing tissues (Ricklefs 1968). Gray-breasted Only female Purple and Gray-breasted mar- and Brown-chestedmartins do not exhibit such tins incubate (Hartley 1917, Allen and Nice marked peaks followed by weight recession 1952). (Fig. 1). The growth rate constant of Brown- Weather conditions influence incubation be- chestedMartins (0.284 days-‘) was lower than havior in both Purple and Brown-chestedmar- that reported for Purple and Gray-breasted tins. The Purple Martin incubates for 8 1% of martins (0.384 and 0.395 days-‘, respectively; daylight hours when the ambient temperature Ricklefs 1976). is 14.4”C, but only 69% at 19.8”C (Allen and The nestling periods of Purple and Brown- Nice 1952). The Brown-chested Martin spent chested martins are both about four weeks lesstime on eggs(62%) than the Purple Martin (Finlay 197 1b, this study), whereas that of the does, but incubated at a higher average am- Gray-breasted form has been reported as only bient temperature of 27.6”C. 22 days (Hartley 1917) as well as 28 days Purple Martins usually spend 4-15 min at (Collins, unpubl.). Fledging success(as a per- a time on the eggs,but sometimesover 30 min, centageof nestlingshatched) of Brown-chested especially in bad weather; their inattentive pe- (71%) and Purple martins (70% in Alberta riods generally last lessthan 12 min (Allen and [Finlay 1971b]; 84% in Texas [Brown 19781) Nice 1952, Kendeigh 1952). Finlay (1971a), is similar. Allen and Nice (1952) however, however, noted that the female spendsa long gave a lower figure of only 46% for Purple time away from the nest in very inclement Martins in Michigan during inclement weath- weather. Brown-chested Martins also have er. short inattentive periods, and long spellsat the nest in cool, cloudy weather. Egg losses were much higher for Brown- TABLE 5. Density of Brown-chestedMartins at various feedingstations. Values in the table are numbersofmartins observed at each station expressedas a percentageof the total number of martins observed at all feeding stations. .

Feeding DO Wet All Feeding height weather weather weathers ; 40- site (n = 129) (n = 68) (n = 197) .; (m)

F Open ground 15 0 0 0 _ 30- . 5-50 6.2 0 4.1 : F : . >50 0 0 0 s n . Trees 15 14.7 23.5 19.3 z- 20- . . . 5-50 34.1 39.7 32.0 z . . . >50 0 0 0 . . . . 8 Waterside <5 31.0 0 20.3 . P O-‘ n : 5-50 6.2 47.1 20.3 >50 0 0 0 . Over water <5 6.2 0 4.1 I $4 26 26’ 50 35 314 36 5-50 0 0 0

TEMPERATURE, OC >50 0 0 0

FIGURE 2. The rate of food-gatheringby Brown-chest- Niche breadtti 4.72 2.30 4.76 ed Martins in relation to the ambient temperature in the nNiche breadth B = I/B p, where p, is the proportion of observations in sun. Each point representsa 2-h period. category i (Levins 1968). 34 ANGELA K. TURNER

TABLE 6. Percentageoccurrence (by weight) of insect 1972). Thus, the diet of all speciesof Progne taxa in the diet of nestlingPurple and Brown-chestedmar- and Phaeoprogneis probably affected by bad tins. weather.

Brown-chested Other aspectsof feeding ecology also depend Martinb (n = 223) on weather conditions and nestling age at least in some hirundines. The size of boluses ex- Isoptera 0 0.3 tracted from immature Brown-chested Mar- Odonata 30.2 69.9 tins did not changeas the chicks grew and the Hem&era 2.5 trace Lepidoptera 17.1 20.6 number of feeding visits per hour increasedat Diotera 27.3 2.5 only one nest. In contrast, the bolus size of Himenoptera 7.0 4.9 young Purple Martins increasesuntil they are Coleoptera 2.8 0 at least three weeks old, especially during the * From Walsh (I 978) first 10 days after hatching, and the number bThis study. of feeding visits per hour increasesduring the first 8-l 0 days (Finlay 197 1b, Walsh 1978). In Finlay’s study, feeding rates decreased after FEEDING ECOLOGY day 14, but larger food items were then brought Adult Brown-chested Martins feed mainly on to the nestlings. For British hirundines, the termites, a group that is unavailable to Purple frequency of feeding is also fairly constantafter Martins, which reportedly feed on a wider va- the first one to two weeksof the nestling period riety of prey (Table 1). The weather, however, (Bryant and Gardiner 1979, Turner 1980). affected the diet of Brown-chested Martins be- Thus, the daily food intake varies little after causerain stimulatestermites to swarm (Kirk- an initial period of rapid increase. patrick 1957), and these insectsare not always Among Purple Martins, parents feed their otherwise available; larger prey, such as dra- chicks less frequently during rain, overcast gonfliesand moths, were taken in dry weather. skies, and temperatures below 13°C (Finlay Nestling Brown-chested Martins were fed 197 1b). Brown-chested Martins also made more dragonfliesand fewer Diptera (by weight) fewer feeding visits and took longer to collect than has been reported for nestling Purple a bolus of food in bad weather, although day- Martins, at least in Canada (Walsh 1978, Table time temperatures in my study did not fall 6). The small quantity of Diptera brought to below 23°C. The low feeding frequency of both the former may reflect the relative scarcity of speciesis probably due to the scarcity of food large flies in this area (Turner 1983). I have in bad weather at Guanare and in temperate no information about the relative availability areas (Turner 1980, this study). Wet weather of Odonata in Venezuela and Canada. Chicks also reduced the number of feeding sites used of both martins, however, were fed propor- by Brown-chestedMartins as it does in British tionately more dragonflies and fewer syrphids hirundines (Waugh 1978). as they grew (Finlay 197 1b, Walsh 1978, this Weather, and consequently feeding condi- study). Since the tropical dragonflies averaged tions, thus influence the incubation behavior three times larger than the syrphidsin the birds and feeding ecology of both temperate and at of my study (mean dry weights of 93.1 and least one tropical speciesof martin despite the 32.5 mg, respectively), it may have been more warmer temperature of the tropical site. profitable for the adults to collect them, rather than syrphids, once the nestlings were large ACKNOWLEDGMENTS enough to I thank the Royal Society of London and CONICIT of Adult and nestlingSouthern, Gray-breasted, Venezuela for financial support, UNELLEZ and the Uni- versity of Los Andes for laboratory facilities, C. T. Collins and Caribbean martins commonly consume for the use of unpublisheddata, and D. M. Bryant, E. H. Odonata and Lepidoptera (Beebe 1924; ffrench Burtt, Jr., H. W. Kale, and an anonymous reviewer for 1976; Collins, unpubl.; Turner, unpubl.). This useful comments on the manuscript. is in marked contrast to other smaller hirun- dines which eat few large insects, relying in- LITERATURE CITED stead mainly on Diptera and Hymenoptera ALLEN, R. W., AND M. M. NICE. 1952. A study of the (Beal 19 18; Waugh 1979; Turner 1983). breedingbiology of the Purple Martin (Progne subis). Since dragonflies are scarce in cool, cloudy Am. Midl. Nat. 47:606-665. BEAL, F. E. L. 1918. Food habitsof the swallows,a family weather (this study), martins then consume of valuable native birds. U.S. Dep. Agric. Bull. No. other, often smaller, prey. Syrphids are also 619. less active in cloudy weather, which probably BEEBE, W. 1924. Galapagos:worlds end. Putnam, New explains why they form 24% of the nestling York. BROWN, C. R. 1978. Clutch size and reproductivesuccess diet of Purple Martins under sunny conditions, ofadult and subadultPurple Martins. Southwest.Nat. but only 3% under cloudy conditions (Spice 231597-604. BROWN-CHESTED MARTINS 3 5

BROWN,C. R. 1979. Territoriality in the Purple Martin. MOREAU, R. M. 1939. Numerical data on African birds’ Wilson Bull. 91:583-591. behaviour at the nest: s. smithii Leach, the BRYANT,D. M. 1973. The factors influencing the selec- Wiretailed Swallow. Proc. Zool. Sot. Lond. Ser. A tion of food by the House Martin, urbica. 109:109-125. J. Anim. Ecol. 42:539-564. RHEINWALD,G. 1971. Gewichtsentwicklungnestjunger BRYANT,D. M. 1975. Breedingbiology ofHouse Martins Mehlschwalben (Delichon urbica) bei verschiedenen Delichonurbica in relation to aerial insectabundance. Witterungsbedingungen.Charadrius 7: l-7. Ibis 117:180-216. RICKLEFS, R. E. 1967. A graphicalmethod of fitting growth BRYANT,D. M., AND A. GARDINER. 1979. Energeticsof equations to growth curves. Ecology 48:978-983. growth in House Martins, Delichon urbica. J. 2001. RICKLEFS,R. E. 1968. Weight recessionin nestlingbirds. 189:275-304. Auk 85:30-35. FFRENCH,R. 1976. A guide to the birds of Trinidad and RICKLEFS,R. E. 1969. An analysis of nestling mortality Tobago. Rev. ed. Harrowood Books, Valley Forge, in birds. Smithson. Contrib. Zool. 9. PA. RICKLEFS,R. E. 1971. Foraging behavior of Mangrove FINLAY,J. C. 197la. Some effects of weather on Purple Swallowsat Barre Colorado Island. Auk 88:635-6.51,-. Martin activity. Auk 93~231-244. RICKLEFS,R. E. 1976. Growth ratesof birds in the humid FINLAY,J. C. 1971 b. Breedingbiology of Purple Martins New World tropics. Ibis 118:179-297. at the northern limit of their range. Wilson Bull. 83: SPICE, H. 1972. Food habits of nestling Purple Martins. 255-269. M.Sc. thesis, Univ. of Alberta, Edmonton. GONZALEZ,E. 1948. Datos detalladosde climatologia de TURNER,A. K. 1980. The use of time and energy by Venezuela. Ministerio de Sanidady AsistenciaSocial, aerial-feeding birds. Ph.D. diss., Univ. of Stirling, Caracas,Venezuela. Scotland. HARTLEY,G. I. 1917. Nesting habits of the Grey-breast- TURNER,A. K. 1983. Food selection and the timing of ed Martin, p. 328-341. In W. Beebe, G. I. Hartley, breeding in the Blue-and-White Swallow. Ibis 125: and P. G. Howes, Tropical wildlife in British Guiana. 450-462. New York Zoological Society, New York. WALSH,H. 1978. Food of nestling Purple Martins. Wil- HUDSON,W. H. 1920. Birds of La Plata. Dent, London. son Bull. 90:248-260. JOHNSTON,R. F. 1967. Seasonalvariation in the food of WAUGH,D. R. 1978. Predation strategiesin aerial-feed- the Purple Martin, Progne subis,in Kansas. Ibis 109: ing birds. Ph.D. diss., Univ. of Stirling, Scotland. 8-13. WAUGH, D. R. 1979. The diet of Sand Martins during KENDEIGH,S. C. 1952. Parental care and its evolution the breeding season. Study 26:123-128. in birds. Univ. Illinois Press, Urbana. KIRKPATRICK,T. W. 1957. Insectlife in the tropics. Long- Facultad Forestales, Universidadde Los Andes, M&ido1-1 mans, London. Venezuela.Present address: Department ofBiological Sci- LACK, D. 1947. The significanceof clutch size. Ibis 89: ences,University of Stirling, Stirling, FK9 4LA, Scotland, 302-352. UK. Received 6 November 1982. Final acceptance5 July LEVINS,R. 1968. Evolution in changingenvironments: 1983. some theoretical explorations.Princeton Univ. Press, Princeton, NJ.

The Condor 86:35 8 The Cooper Ornithological Society 1984

RECENT PUBLICATIONS

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