Breeding success of short-tailed shearwaters following extreme environmental conditions

Abstract

Extreme weather events are increasing in frequency, causing disruption to global ecosystems. Large-scale events, such as marine heatwaves, can impact the abundance of prey species, which consequently influences the behaviour of top-level predators such as seabirds. The short-tailed shearwater Ardenna tenuirostris is a trans-hemispheric migrant with typically a highly synchronous breeding phenology. Here, we document short-tailed shearwater colony occupancy for the period 2011-2020, with a focussed assessment of their breeding success in the 2019/20 season, which followed a marine heatwave that occurred predominantly in the non-breeding areas in the North Pacific Ocean. The return of the birds to their breeding colonies in southeast Australia was delayed by approximately 2 wk in October 2019, and the subsequent breeding season ended with only 34% breeding success, with nest abandonment beginning in the incubation phase. A North Pacific marine heatwave in 2019, associated with a mass mortality event of over 9000 birds (‘wreck’ of beach-washed birds), led to reduced adult body condition and carry-over effects causing egg and chick failures during the subsequent breeding season. Localised weather events (i.e. flooding of burrows due to heavy rainfall) also influenced breeding outcomes of the 2019/20 season. The relationship between wreck events and seabird breeding ecology is an understudied area, partly due to the difficulties around quantifying the scale of wrecks. Our study is one of few that documents poor seabird breeding success following the extreme marine conditions which have persisted in the North Pacific Ocean since 2013.

Burrows buffer nest temperatures and offer a stable thermal microclimate for threatened seabird chicks during extreme events

“…Consequently, Atlantic pu n chick body temperature has been observed to signi cantly decrease during periods of high precipitation (Vongraven, Aarvik & Bech, 1987). Moreover, burrowing seabird colonies are often vulnerable to ooding and collapse during heavy rainfall, particularly in unvegetated areas, which can lead to breeding failure (Tiller et al, 2000;Glencross, Lavers & Woehler, 2021). For example, a mass mortality of Atlantic pu n chicks was recorded following extreme precipitation and cold weather in Witless Bay Ecological Reserve (Wilhelm et al, 2013).…”

Evaluating the breeding phenology of the endangered ‘a‘o (Newell’s Shearwater Puffinus newelli) on Kaua‘i to better focus conservation actions and management decisions

“…Several hypotheses have been presented to explain the evolution of asynchronous breeding seasons in seabirds. Tropical and sub-tropical species may be less constrained than temperate species by dramatic changes in weather towards the end of the breeding season that could result in total breeding failure (Brooke 1990, Glencross et al 2021). Alternatively, smaller species have a shorter breeding season than larger ones and thus have some flexibility in when they can initiate breeding each year (Brooke 1990).…”

Delay in Adélie penguin nest occupation restricts parental investment in nest construction and reduces reproductive output

“…Because overall population change integrates key demographic parameters including reproductive success, understanding the short‐term response of demographic parameters is a critical element in developing an understanding of the overall drivers of population change (Fayet et al., 2021 ; Labrousse et al., 2021 ). Reproductive success may be driven by both extrinsic (environmental) and intrinsic (behavioural) factors (Glencross et al., 2021 ; Morandini et al., 2021 ) operating on various spatial and temporal scales (Barreau et al., 2019 ; Caravaggi et al., 2019 ; Emmerson & Southwell, 2022 ).…”