Breeding biology of the Chilean Elaenia (Elaenia chilensis), a long-distance migratory passerine in South America

GOROSITO, C.A.; TUERO, D.T.; CUETO, V.R.

ARDEA

NEDERLANDSE ORNITHOLOGISCHE UNIE

Año: 2022 vol. 110 p. 227 - 238

0373-2266

Studies examining breeding biology provide information aboutreproductive parameters, which are useful in formulating life-historytheories. Although these studies have notably increased in theNeotropics in recent years, some gaps remain; thus, more research isneeded to better understand life-history strategies of New Worldbirds. Furthermore, research into the breeding biology of migratorybirds is crucial to advance our understanding of trade-offs betweenreproduction and migration in Neotropical austral migrant birds. Ouraims were to describe in detail the breeding biology of the ChileanElaenia Elaenia chilensis, a long-distance Neotropical australmigrant, and to discuss current life-history theories for New Worldpasserines. We monitored 113 nests during four consecutive breedingseasons (2014/2015–2017/2018) in the Andean-Patagonian Forest. Thebreeding season lasted 77 days and the nesting period, from egglaying to fledging, had a mean duration of 29.9 days. Mean clutchsize was 2.4 eggs (range: 1–3) and decreased throughout thebreeding season. The incubation and nestling stages lasted c. 14 dayseach. Fledgling number also decreased as the season progressed. Themean ± SE daily nest survival rate was 0.960 ± 0.005, correspondingto an overall nest success of 29.5%. Predation was the main cause ofnest loss (61.1%). Reproductive parameters of the Chilean Elaeniacoincide with characteristics of high-survival species that investlittle in reproduction. Despite being a long-distance migrant, itslife-history strategy does not seem to be much faster than that ofits tropical resident congeners. This might not support the resultreported in the Northern Hemisphere that migratory birds have afaster pace of life than resident birds.