Age and terminal reproductive attempt influence laying date in the thorn‐tailed rayadito

Abstract

Age‐specific variation in reproductive effort can affect population dynamics, and is a key component of the evolution of reproductive tactics. Late‐life declines are a typical feature of variation in reproduction. However, the cause of these declines, and thus their implications for the evolution of life‐history tactics, may differ. Some prior studies have shown late‐life reproductive declines to be tied to chronological age, whereas other studies have found declines associated with terminal reproduction irrespective of chronological age. We investigated the extent to which declines in late life reproduction are related to chronological age, terminal reproductive attempt or a combination of both in the thorn‐tailed rayadito Aphrastura spinicauda, a small passerine bird that inhabits the temperate forest of South America. To this end we used long‐term data (10 years) obtained on reproductive success (laying date, clutch size and nestling weight) of females in a Chilean population. Neither chronological age nor terminal reproductive attempt explained variation in clutch size or nestling weight, however we observed that during the terminal reproductive attempt older females tended to lay later in the breeding season and younger females laid early in the breeding season, but this was not the case when the reproductive attempt was not the last. These results suggests that both age‐dependent and age‐independent effects influence reproductive output and therefore that the combined effects of age and physiological condition may be more relevant than previously thought.

Female extra‐pair behavior is not associated with reduced paternal care in Thorn‐tailed Rayadito

“…Rayaditos have an average lifespan of 4.8 years, with some individuals reaching the age of 9 years (Quirici et al., 2019). In Navarino, female rayaditos lay one clutch of 1–10 eggs per breeding season, although replacement clutches are observed.…”

Influence of the haemosporidian Leucocytozoon spp. over reproductive output in a wild Neotropical passerine, the Thorn‐tailed Rayadito (Aphrastura spinicauda)

“…As this species is a secondary cavity nester (Remsen 2003), it easily adopts artificial nestboxes, thus facilitating monitoring of its reproductive biology and behavioural ecology. Thorn-tailed Rayaditos can live to at least 9 years (Quirici et al 2019), are socially monogamous without obvious sexual dimorphism, and exhibit biparental care (both members of the pair contribute to nest-building, incubation and the feeding of nestlings; Moreno et al 2005, Espíndola-Hernández et al 2017. Nest construction lasts 9-20 days (Moreno et al 2005).…”

“…Nest construction lasts 9-20 days (Moreno et al 2005). Females lay one clutch per breeding season during the austral spring (Moreno et al 2005) and the laying date depends on the age and terminal reproductive attempt of females (Quirici et al 2019). Clutch sizes vary with latitude (mean 2.5 vs. 4.5 at lower and higher latitudes, respectively; Quirici et al 2014) and elevation (4.1 vs. 4.5 at lower and higher elevations, respectively; Altamirano et al 2015).…”

Does baseline corticosterone influence inter-annual apparent survival of the Thorn-tailed Rayadito?

“…Thorn-tailed Rayadito are small (~11 g) and usually lay one clutch per breeding season during the austral spring [37]. Thorn-tailed Rayaditos can live at least nine years (nestlings marked and recaptured nine years later) and their mean the lifespan is 4.8 yr [38]. The nest construction period lasts 6-15 days, and the incubation period is 9-15 days.…”