SHORT CO,MMUNICATIONS 437

Wilson Bull., 11 l(3), 1999, pp. 437-439

Cooperative Foraging in the Mountain Caracara in Peru

Jason Jones,2’

ABSTRACT.-Cooperative foraging behavior is detail observations of cooperative foraging rarely observed in ground-walking birds. I report on behavior in the Mountain Caracara (Phalco- observations of cooperative foraging behavior by boenus megalopterus). This species is adept Mountain Caracaras (Phalcoboenus megalopterus) in the puna region of Peru in September of 1995. On at ground foraging and in non-urban areas several occasions, three individuals (two adults and feeds on large arthropods, rodents, and birds one immature) were observed working together to turn (Brown and Amadon 1968). Breeding usually over large rocks to obtain prey from beneath. These occurs between October and December with cooperative foraging events are notable in that, unlike two, rarely three, eggs laid (Brown and Ama- cooperative foraging behavior observed in other don 1968). ground-walking birds, only one individual obtained prey from a given cooperative effort. The presence of STUDY AREA the immature individual may be indicative of delayed dispersal, a behavior not previously described for this The observations were made in the Peruvian puna poorly known species. Received 14 Dec. 1998, ac- zone on the road between the towns of Quillabamba cepted 28 March 1999. and Ollantaytambo, Department of Cuzco (13” 9 ’ S, 72” 14 ’ W, 3750 m elevation). This region is charac- terized by dry grasslands, dominated by genera such as Calamagrostis and Fesfuca with interspersed shrubs Cooperative foraging involves two or more of the genera Astragalus, Berberis, and Lupinus (Park- individual organisms assisting one another in er et al. 1982). Mountain Caracaras are common in this obtaining a food item. Among vertebrates, region (Parker et al. 1982) and are often found near this behavior is well described in many social towns where they feed on refuse and carrion (White and Boyce 1987). mammals (Macdonald 1983, Serfass 1995) and some fish (Dugatkin and Mesterton-Gib- RESULTS bons 1996) but is relatively uncommon in I observed cooperative rock-turning on four birds (Sullivan 1984). Among birds, cooper- occasions from l-6 September 1995, as I ative hunting appears most frequently in sea- watched three individuals (two adults and one birds (Parasitic Jaegers, Stercorarius parusi- immature) foraging together on the puna ticus, Pruett-Jones 1980; Brown and Ameri- grassland. The immature bird was easily dis- can White pelicans, Pelecanus occidentalis tinguished by its plumage. On each occasion, and P. erythrorhynchos, J. Jones, unpub. one of the adults approached a large rock, data). Examples from land birds include the walked around it, uttered a high-pitched cooperative hunting behavior exhibited by kieeer, and then stood by the rock. Apparently Harris ’ Hawks (Parubuteo unicinctus; Mader responding to the vocalization, the other in- 1979, Bednarz 1988), Golden Eagles (A&la dividuals joined the first at the rock and pro- chrysaetos; Collopy 1983) and Crested Ca- ceeded to work together to flip the rock from racaras (Caracara plancus; Morrison 1996). its resting place, with each bird using one of Most of these instances of cooperative hunt- its talons. The bird that made the call partic- ing involve highly mobile prey items; coop- ipated in the the turning but also appeared to erative foraging for less mobile organisms is act as a “watcher” and was the individual re- uncommon (Sullivan 1984). In this report, I sponsible for prey capture. On one occasion, the item was captured by an adult which then ’ ’ 4974 Lakeshore Rd., Kelowna, British Columbia, gave it to the immature bird. No begging vo- Canada, VlY 7R3. 2 Present address: Dept. of Biology, Queens’ Univ., calizations were uttered by the younger bird Kingston, Ontario, Canada, K7L 3N6; nor did it adopt any unusual posture. Each lift- E-mail: [email protected] ing event took approximately 30 min from call 438 THE WILSON BULLETIN l Vol. 111, No. 3, September 1999 to prey capture. This species, although a ward is perhaps indicative of the length of ground-foraging specialist, has weak legs time these birds remain together as a foraging (Brown and Amadon 1968). After examining unit; that is, an individual is willing to help the rocks (approximate dimensons 30 X 20 X today because its turn will come eventually 10 cm), I do not believe that one individual (see Tiivers 1971 for discussion of reciprocal could have turned over any of the rocks by altruism). itself. Congeners of the Mountain Caracara hatch At no time during the days of observation their eggs in December and fledglings are usu- was the immature bird more than 100 m from ally independent by March (Brown and Ama- one or the other of the adults, although the don 1968). As my observations took place in adults were often separated by distances up to September, the immature member of the trio 500 m. In a series of 12 one-hour watches (n was probably a chick from a previous breed- = 4 for each individual), I determined that the ing effort and its presence, therefore, may rep- two adults appeared to spend more time for- resent delayed dispersal. Delayed dispersal is aging than did the immature bird (adult = fairly common in Neotropical raptors (Mader 68.6%, imm. = 52.3%) although the differ- 1981). How common delayed dispersal is in ence was not statistically significant (x2 = Mountain Caracaras and how it may affect the 3.334, df = 1, P = 0.067). incidence of cooperative foraging, is uncer- Subsequent investigation revealed that tain. worms or arthropods could be found under most (19 of 24) of the rocks in the vicinity; ACKNOWLEDGMENTS several of the rocks (5 of 24) also hid rodent I thank .I. Barg, E. Carruthers, E Chavez-Ramirez, runways. Examination of the surrounding D. Jones, W. Rendell and four anonymous reviewers grassland showed that prey items of a similar for providing helpful comments on earlier drafts of this size but different taxa (e.g., grasshoppers rath- manuscript. er than millipedes) were available without LITERATURE CITED rock lifting. BEDNARZ, J. C. 1988. Cooperative hunting in Harris ’ DISCUSSION Hawks (Parabuteo unicinctus). Science 239: Unlike most land bird species, Mountain 1525-1527. BROWN, L. AND D. AMADON. 1968. Eagles, hawks and Caracaras were not using cooperative foraging falcons of the world. Vol. 2. McGraw-Hill, New behavior to pursue and subdue large, highly York. mobile prey items. Rather, they required co- COLLOPY, M. W. 1983. Foraging behavior and success operation to obtain access to otherwise inac- of Golden Eagles. Auk 100:747-749. cessible prey items. While the turning over of DUGATKIN, L. A. AND M. MESTERTON-GIBBONS.1996. small rocks was one of the main foraging be- Cooperation among unrelated individuals: recip- rocal altruism, by-product mutualism and group haviours exhibited by these individuals, the selection in fishes. Biosystems 37: 19-30. cooperative rock-turning events did not occur MACDONALD, D. W. 1983. The ecology of carnivore within the set watches and did not seem to social behaviour. Nature 301:379-384. represent a major foraging strategy for these MADER, W. J. 1979. Breeding behavior of a polyan- individuals. The main difference between the drous trio of Harris ’ Hawks in southern Arizona. cooperative behavior observed in Mountain Auk 96:776-788. Caracaras and that observed in other cooper- MADER, W. J. 1981. Notes on nesting raptors in the llanos of Venezuela. Condor 83:48-51. atively foraging birds is that only one individ- MOFXISON, J. L. 1996. Crested Caracara (Caracura ual obtained food from a given foraging event; plancus). In The birds of North America, no. 249 Harris ’ Hawks, for example, share large prey (A. Poole and E Gill, Eds.). The Academy of Nat- that are cooperatively caught (Bednarz 1988). ural Sciences, Philadelphia, Pennsylvania; The This disparity in obtaining a food reward may American Ornithologists ’ Union, Washington, D.C. even out over time (e.g., one of the four prey PARKER, T A., III, S. A. PARKER, AND M. A. PLENGE. 1982. An annotated checklist of Peruvian birds. items was given to the immature bird) but Buteo Books, Vermillion, South Dakota. there apparently is often no immediate reward PRUETT-JONES,S. G. 1980. Team-hunting and food for some of the individuals participating. That sharing in Parasitic Jaegers. Wilson Bull. 92:524- individuals are willing to help without a re- 526. SHORT COMMUNICATIONS 439

SERFASS,T L. 1995. Cooperative foraging by North TRIVERS, R. L. 197 1. The evolution of reciprocal altm- American river otters, Lutra canadensis. Can. ism. Q. Rev. Biol. 46:35-57. Field-Nat. 109:4X-459. WHITE, C. M. AND D. A. BOYCE. 1987. Notes on the SULLIVAN, K. A. 1984. Cooperative foraging and court- Mountain Caracara (Phalcoboenus megalopte- ship feeding in the Laughing Gull. Wilson Bull. rus) in the Argentine puna. Wilson Bull. 99: 96:710-711. 283-284.

Wilson Bull., 11 l(3), 1999, pp. 439-440

Predation by Rufous Motmot on Black-and-Green Poison Dart Frog

Terry L. Master ’

ABSTRACT-I observed a Rufous Motmot (Bar- the black-and-green poison dart frog (Dendro- yphthengus mart@ feeding a black-and-green poison bates auratus) and phantasmal poison dart dart frog (Dendrobates auratus) to another motmot in frog (Dendrobates tricolor). However, these the Caribbean Slope lowland rainforest of northeastern Costa Rica. Neither individual appeared to suffer any frogs were raised in captivity and either do not ill effects from what was probably courtship feeding. produce or have relatively low levels of the Small vertebrates are typical prey for the larger species characteristic skin toxins &richer 1997; C. of motmots. Blue-crowned Motmots (Momotusmom- Rowsom, pers. comm.). ota) have been observed consuming several species of At approximately 9:30 CST on 26 March poison dart frogs raised in captivity but captive reared 1995, an adult Rufous Motmot was observed frogs either do not contain, or have reduced levels of, the toxins that native frogs produce. Relatively little is in secondary lowland tropical forest from a known about the effects of poison dart frog toxins on hiking trail located at Estacion Biologica La predators. Presumably, the digestive system of the Ru- Suerte, near Cariari, Limon Province, north- fous Motmot is capable of neutralizing the potentially eastern Costa Rica (10” 26 ’ N, 83” 46 ’ W). toxic effects of such prey. Received 15 Sept. 1998, The bird landed 25 m from the trail on an accepted 1.5 Feb. 1998. exposed perch 3 m above the ground and was easily observed for approximately 4 min. Af- ter 4 min another individual landed on the Poison dart frogs have long been known to same branch next to the first individual. The possess toxic skin secretions, and, because of newly arrived motmot was carrying a black- their bright coloration, are thought to be apo- and-green poison dart frog in its beak which sematic to visually hunting predators such as it fed immediately to the first individual. It is Rufous Motmots (Baryphthengus martii) not possible to distinguish between sexes in which presumably have excellent color vision Rufous Motmots; however, this behavior was (Brodie and Tumbarello 1977). Smith (1975) interpreted as a male who was feeding the fe- demonstrated that hand-reared Torquoise- male as a courtship gesture. Both individuals browed Motmots (Eumomota superciliosa) had diagnostic black breast marks and raquet- showed an innate avoidance of snake-shaped tails indicative of adult birds, suggesting that models with patterns simulating those of coral this was probably not a fledgling being fed. snakes. All other snake models were readily The pair continued sitting on the branch for attacked implying that aposematic coloration is a deterrent to this species. Observations in- approximately 30 min after which they flew dicate that Blue-crowned Motmots (Momotus off together into the forest. Neither individual momota) at the National Aquarium consume appeared to suffer any ill effects from either several species of poison dart frogs including grasping or consuming the poison dart frog. The typical diet of motmots varies somewhat in conjunction with body size. Smaller species I Dept. of Biological Sciences, East Stroudsburg Univ., East Stroudsburg, PA 18301; prefer insects while larger species consume in- E-mail: [email protected] sects along with other invertebrates, small ver-