FIRST OBSERVATION OF INFANTICIDE AND CANNIBALISM IN NEST OF CHIMANGO CARACARA ... by filial cannibalism in the Chimango Caracara (Milvago.
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LETTERS
VOL. 46, NO. 4
J. Raptor Res. 46(4):412–413 E 2012 The Raptor Research Foundation, Inc.
FIRST OBSERVATION OF INFANTICIDE AND CANNIBALISM IN NEST OF CHIMANGO CARACARA (MILVAGO CHIMANGO) KEY WORDS: Chimango Caracara; Milvago chimango; Argentina; cannibalism; infanticide; nesting. Infanticide and cannibalism are behaviors exhibited between individuals of the same species. Infanticide is aggressive behavior in which a mature animal kills young offspring; cannibalism is a feeding behavior exhibited by genetically related or unrelated individuals of the same species. Filial infanticide occurs when parents kill offspring in their own brood and is sometimes followed by the parents’ consumption of their own young, termed filial cannibalism. Infanticide and cannibalism have been documented in many wildlife species including several species of raptors belonging to several different families (Jones and Manez 1990, Negro et al. 1992, Boal and Bacorn 1994, Garcı´a Dios 2003, Margalida et al. 2004, Korn ˇ an and Macek 2011, Ortega-Jimenez et al. 2011). These behaviors are difficult to witness, however, especially filial infanticide and filial cannibalism. To appropriately assign these behaviors, a genetic relationship between predator (parent) and prey (offspring) must be established. Here, we report the first case of filial infanticide followed by filial cannibalism in the Chimango Caracara (Milvago chimango), a common but little-studied raptor that is well adapted to human environments and is often observed in urban areas (Fraga and Salvador 1986, Bellocq et al. 2008). We monitored a nest of Chimango Caracaras during the austral summer 2010–11 in La Pampa province, Argentina (36u439S, 64u169W). The caracaras built the nest on a calde´n tree (Prosopis caldenia) within 30 m of a house, a behavior commonly observed in this raptor species (Morrison and Phillips 2000, Biondi et al. 2008). Nest tree height and nest height were 6.3 m and 2.8 m, respectively. The behaviors of parents and nestlings were recorded using digital video recording equipment (Vivotek Outdoor Day and Night Network Bullet Camera IP7330, Vivotek Inc., New Taipei City, Taiwan, and a Hard Disk Lacie d2 Network, LaCie U.S., Oregon, U.S.A.). This equipment was installed 2 d after we found the nest containing two unhatched eggs, on 13 February 2011. Nest activities were recorded continuously for 16 d, until 2 March. Both parents had been captured previously and marked with alphanumeric-coded PVC rings, which facilitated individual recognition in the video recordings. The first egg hatched on the morning of 19 February (at approx. 1000 H) and the second egg hatched a day later, on 20 February (at 1100 H). Both parents delivered food to the nest between 19 and 25 February (n 5 73 deliveries). The food items delivered to the chicks included invertebrate prey (54.8%), carrion (11%), birds (2.7%), and small mammals (1.4%). Among invertebrates, insects were the
primary prey (97.5%); other invertebrate prey included annelids (2.5%). On 25 February at 0730 H, the marked female entered the nest, attacked and killed both nestlings using her talons and her bill. She remained in the nest until 0802 H, but did not feed on the dead nestlings. The marked adult male arrived at the nest at 0809 H with food in its bill. After a few minutes, the male began feeding on the prey it had brought and also on the dead nestlings. Between 0826 H and 1315 H, the female Chimango Caracara returned to the nest on four occasions and took the remains of the dead nestlings out of the nest. After his first visit, the male Chimango Caracara returned to the nest on two other occasions between 1002 H and 1604 H. That was the last time the parents were recorded, and no other Chimango Caracaras were recorded in the nest until the video equipment was removed at 1848 H on 2 March. A partial reduction of brood size by infanticide has sometimes been explained by constraints on the availability of food resources (Ingram 1959). Such brood reduction can be an important mechanism to ensure survival of some nestlings when food resources are insufficient to feed the entire brood. Instead of simple brood reduction, the killing behavior exhibited by these adult Chimango Caracaras toward their nestlings resulted in loss of the entire brood. Loss of entire broods by infanticide has been documented previously in raptors but only for nests with broods containing a single young (Ortega-Jimenez et al. 2011). To our knowledge ours is the first case, for a raptor species, of an entire brood lost by infanticide with brood size larger than one nestling. The nest we monitored was delayed in terms of the reported breeding chronology for the species (Chimango Caracaras typically lay their eggs between September and November [Fraga and Salvador 1986, Morrison and Phillips 2000]). The eggs in this nest were laid in late January, one of the latest egg-laying dates recorded for the species. Thus, food shortage may be a plausible but not the single explanation for the behavior we observed. Other possible factors could be related to stress associated with breeding near humans or with the camera itself. However, we monitored other Chimango Caracara nests located near houses in the same area and the chimangos nested successfully in them (n 5 38; C. Solaro unpubl. data). Parents at this nest where cannabilism was observed may also have been young and inexperienced and thus unable to raise the nestlings successfully (Newton 1998).
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LETTERS
We are grateful to M. Galmes and G. Almeida for providing the video recording equipment, to G. Ferna´ndez Riga for her comments on the manuscript, and to C. Ortı´z-Echagu¨e for allowing us to carry out this study on her property. This study was funded by the PI-R018 of the Department of Natural Resources, University of La Pampa. JHS and CS were funded by the National Research Council of Argentina (CONICET).—Claudina Solaro (email address: csolaro@ conicet.gov.ar) and Jose´ Herna´n Sarasola, Centro para el Estudio y Conservacio´n de las Aves Rapaces en Argentina (CECARA), Universidad Nacional de La Pampa, Avda. Uruguay 151, 6300 Santa Rosa, La Pampa, Argentina, and Instituto de las Ciencias de la Tierra y Ambientales de La Pampa (INCITAP), Consejo Nacional de Investigaciones Cientı´ficas y Te´cnicas de Argentina (CONICET), Avda. Uruguay 151, 6300 Santa Rosa, La Pampa, Argentina. LITERATURE CITED BELLOCQ, M.I., J. FILLOY, AND P.I. GARAFFA. 2008. Influence of agricultural intensity and urbanization on the abundance of the raptor Chimango Caracara (Milvago chimango) in the Pampean region of Argentina. Annales Zoologici Fennici 45:128–134. BIONDI, L.M., M.S. BO´, AND A.I. VASSALLO. 2008. Experimental assessment of problem solving by Milvago chimango (Aves: Falconiformes). Journal of Ethology 26:113–118. BOAL, C.W. AND J.E. BACORN. 1994. Siblicide and cannibalism at Northern Goshawk nests. Auk 111:748–750. FRAGA, R.M. AND S.A. SALVADOR. 1986. Biologı´a reproductiva del Chimango (Polyborus chimango). Hornero 12: 223–229.
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Received 10 May 2011; accepted 9 July 2012 Associate Editor: Joan M. Morrison
