Predation by Crested Caracaras (Caracara plancus) on nests of the endemic Chubut Steamerducks (Tachyeres leucocephalus)

FORMOSO ANAHÍ E.; D'AGOSTINO ROMINA; AGÜERO MARÍA LAURA; AGU ARIEL

JOURNAL OF RAPTOR RESEARCH

RAPTOR RESEARCH FOUNDATION INC

Lugar: Lawrence, Kansas; Año: 2024 vol. 58 p. 1 - 6

0892-1016

Crested Caracaras (Caracara plancus) are opportunistic raptors with diurnal habits that feed on a great variety of prey and carrion, nestlings and eggs. In the coastal area of Chubut province (Argentina), it co-occurs with Chubut Steamerducks (Tachyeres leucocephalus), an endemic and vulnerable species. Here we report observations and timing of detection of Crested Caracara on nests of Chubut Steamerducks in the Interjurisdictional Marine Park in Northern San Jorge Gulf (Chubut, Argentina). We looked for nests on islands and islets in the park between September to December in 2015 and 2016. Using camera traps installed at 21 nests for a total of 166 camera nights. We recognized a total of 27 detections. We detected the presence of Caracara in 15% and 37% of the nests in 2015 and 2016, respectively. Our findings are consistent with those carried out in other species of steamerducks such as Fuegian Steamerduck (T. pteneres) in Chile; but contrast with evidence from Southern Argentina, where Chimango Caracara (Milvago chimango) was the main predator on steamerducks (Fuegian Steamerduck and Flying Steamerduck (T. patachonicus)). Furthermore, we found that the activity pattern of Crested Caracaras nest visits overlapped with the recesses pattern of Chubut Steamerducks. This foraging behavior would be responding to the fact that Crested Caracaras are visual predators and take advantage of the incubation pattern of Chubut Steamerducks to detect nests. In this study, our reports contribute to expanding the information on Crested Caracara food habits and increase understanding of potential limiting factors on Chubut Steamerducks nesting success.