Fruit abundance may fine‐tune timing of reproduction of the Chilean Elaenia ( Elaenia chilensis ), a long‐distance migratory bird in South America

GOROSITO, CRISTIAN A.; TUERO, DIEGO T.; CUETO, VICTOR R.

IBIS

WILEY-BLACKWELL PUBLISHING, INC

Año: 2023

0019-1019

Timing of reproduction has a great impact on the breeding success of birds because amismatch with the moment when environmental conditions are warm or when food ismost plentiful can reduce nestling survival and increase the energetic cost of parentalcare. Consequently, birds synchronize gonadal maturation with the most favourable environmental conditions, using photoperiod changes throughout the year as an initial proximal cue. Additionally, non-photic cues, such as temperature and food abundance, maybe necessary to fine-tune reproductive timing. However, the influence of non-photic cueson finely tuning reproductive timing is not yet fully understood for migratory birds.Here, we evaluate how much non-photic cues influence the reproductive timing of theChilean Elaenia Elaenia chilensis, a long-distance migrant that reproduces in the Andean–Patagonian Forest. We assessed associations of mean temperature, ripe fruit and arthropod abundances with the number of nests in the laying period, and also with the numberof nests with hatchlings. In both analyses we used cross-correlations and partial leastsquares path modelling. Mean temperature was not consistently associated with thebreeding phenology of Chilean Elaenias. The increase in number of nests in the layingperiod was preceded by the increase in caterpillar abundance and coincided with theincrease in ripe fruit abundance. The timing of nests with hatchlings matched with thetiming of highest ripe fruit abundance. Both types of food could contribute to the beginning of reproduction of birds and be used as proximal cues by Chilean Elaenias. Ripefruits would also be beneficial for nestling growth because parents feed them with fruits,and might potentially play an ultimate role in reproduction. Because ripe fruit abundance was related to the egg-laying and hatching stages, it may be the main cue used byChilean Elaenias to fine-tune reproductive timing. These findings allow advances in ourunderstanding of the importance of non-photic cues in the reproductive phenology ofmigratory birds and also generalize our knowledge among regions and taxa, as most studies on this topic focus on the Northern Hemisphere.