Rapid plastic breeding response to rain matches peak prey abundance in a tropical savanna bird

Abstract

Changes in climate are shifting the timing of life cycle events in the natural world. Compared to northern temperate areas, these effects are relatively poorly understood in tropical and southern regions, where there is limited information on how timing of breeding and food availability are affected by climatic factors, and where patterns of breeding activity are more unpredictable within and between years. Combining a new statistical modelling approach with 5 years of continuous individual‐based monitoring of a monsoonal tropical insectivorous bird, we quantified (a) the proximate climatic drivers at two trophic levels: timing of breeding and abundance of arthropod prey; (b) the effect of climate variation on reproductive output and (c) the role of individual plasticity. Rainfall was identified as the main determinant of phenology at both trophic levels. Throughout the year, likelihood of egg laying increased very rapidly in response to even small amounts of rain during the preceding 0–3 weeks. Adult body mass and male sperm storage also increased rapidly after rain, suggesting high breeding preparedness. Additionally, females were flexible, since they were more likely to nest whether their previous attempt was longer ago and unsuccessful. Arthropod abundance also increased after rainfall, but more slowly, with a peak around 10 weeks. Therefore, the peak food availability coincided with the presence of dependent fledglings. Fitness benefits of nesting after more rain appeared to be linked to offspring quantity rather than quality: nest attempts following higher rainfall produced larger clutches, but showed no improvement in nestling mass or relative fledging success. The response of clutch size to rainfall was plastic, since repeated sampling showed that individual females laid larger clutches after more rain, possibly mediated by improved body mass. Rapid, individually flexible breeding in response to rainfall and slower increase in arthropod abundance also as a response to rainfall, might buffer insectivorous species living in tropical seasonal environments from climate change‐induced phenological trophic mismatches.

Evolutionary drivers of seasonal plumage colours: colour change by moult correlates with sexual selection, predation risk and seasonality across passerines

“…Both species have high annual survival rates (Leitão et al ) and live in the tropics, where predation risk on fairy‐wrens appears to be relatively low (Cain et al ) and where reduced seasonality may favour less well‐defined breeding schedules (Leitão et al ). In purple‐crowned fairy‐wrens ( M. coronatus ), seasonal plumage colours appear to be in the process of being lost due to a lack of strong sexual selection (Kingma et al ; Fan et al ) and a lack of a defined breeding season, as the species can breed year‐round in response to rainfall (Hidalgo Aranzamendi et al ).…”

“…It has previously been shown that mammals and birds that moult from brown to white pelage to maintain crypsis against snow have limited plasticity in response to rapid changes in the timing and duration of snow cover, resulting in low survival (Mills et al 2013;Imperio et al 2013;Zimova et al 2014;Zimova et al 2016;Atmeh et al 2018;Mills et al 2018). To what extent passerines have the capacity to adjust the timing of colour change in response to climate change is presently unknown, as are the consequences for sexual selection (Cockburn et al 2009;Hau et al 2017) and predation risk. In at least some species the timing of the moult to conspicuous breeding plumage seems flexible, and varies with environmental conditions (e.g.…”

Compensatory Breeding in Years Following Drought in a Desert-Dwelling Cooperative Breeder

“…Although weather conditions in highly seasonal temperate environments can vary considerably between years (Griesser et al, 2017), distinct seasonal weather patterns lead to the relatively predictable onset and duration of annual breeding seasons (Greño et al, 2008;Simmonds et al, 2017;Laplante et al, 2019). This differs somewhat from more arid sub-tropical environments, where breeding seasons typically span many months and animals respond flexibly and opportunistically to highly variable weather conditions and less defined seasonality (Griffith et al, 2016;Hidalgo Aranzamendi et al, 2019). In hotter, drier, and less predictable environments, the effects of variation in weather patterns and of extreme weather events may manifest as foregone or failed breeding in poor years (McCreedy and van Riper, 2015;Conrey et al, 2016;van de Ven, 2017;Cooper et al, 2019;Moore and Martin, 2019;Sharpe et al, 2019).…”

When to start and when to stop: Effects of climate on breeding in a multi‐brooded songbird

“…Although the vast majority of analyses of avian breeding phenology to date have been on northern hemisphere populations, recent multispecies analyses have revealed substantial effects of weather on breeding phenology across a range of Australian bird species (Chambers et al, ; Duursma, Gallagher, & Griffith, , ). A detailed individual‐level study of purple‐crowned fairy‐wrens ( Malurus coronatus coronatus ) in the Australian tropics shows the dependence of breeding phenology and reproductive success on rainfall (Aranzamendi, Hall, Kingma, van de Pol, & Peters, ), but in general, the effect of climate on breeding phenology and individual fitness is less well understood in southern hemisphere bird species. In this study, we investigated the effects of climate variables on the breeding phenology of another multi‐brooded passerine, the superb fairy‐wren ( Malurus cyaneus ), using a long‐term study with 28 years of individual‐based field data.…”

“…A detailed individual-level study of purple-crowned fairy-wrens (Malurus coronatus coronatus) in the Australian tropics shows the dependence of breeding phenology and reproductive success on rainfall (Aranzamendi, Hall, Kingma, van de Pol, & Peters, 2019), but in general, the effect of climate on breeding phenology and individual fitness is less well understood in southern hemisphere bird species.…”