Opportunity costs and the response of birds and mammals to climate warming

Abstract

As global temperatures reach record highs, threats posed by climate change to biodiversity become ever more severe. For endotherms, maintaining body temperature within safe bounds is fundamental for performance and survival. Animals routinely modify their behavior to buffer physiological impacts of high temperatures (eg ceasing activity, seeking shade). However, this can impose substantial costs related to missed opportunities to engage in other important activities, with potentially large but often overlooked consequences for survival and reproduction. Here, we outline behavioral trade‐offs birds and mammals face in navigating thermal landscapes and associated challenges of balancing energy, water, and time budgets; review the rapidly expanding knowledge in this field; and summarize examples – across taxa – of fitness costs during hot weather. We argue that a shift is needed in evaluating the impacts of heat on birds and mammals, and that fitness costs of missed opportunities must be explicitly integrated into climate‐change vulnerability frameworks.

The impacts of heat stress on animal cognition: Implications for adaptation to a changing climate

“…As a consequence, nestling mortality increases at high temperatures (Bourne et al, 2020a). Similar trade‐offs between thermoregulation and foraging or parental care have been described for many species worldwide (e.g., Catry et al, 2015; Cunningham et al, 2021; Edwards et al, 2015; Ma et al, 2018). As the number of hot days increases, these sublethal effects are predicted to drive future population declines (Conradie et al, 2019).…”

“…Below we review the evidence for effects of elevated temperatures on cognition and discuss potential fitness implications. We refer the reader to other studies (Buchholz et al, 2019; Cunningham et al, 2021; Diele‐Viegas & Rocha, 2018; Harvey et al, 2020; Stillman, 2019) for a review of the behavioral and physiological responses to increased temperatures.…”

“…Heat stress can also directly impact animals' ability to breed by altering gametogenesis (Alix et al, 2020; Hansen, 2009). Animals avoid heat stress by modifying habitat use and activity patterns to seek thermal refugia, but such behavioral adjustments may come at the cost of reduced mating opportunities, increased predation risk, and constraints on foraging or offspring provisioning (Bartholomew, 1964; Cunningham et al, 2021). For example, fiddler crabs ( Uca mjoebergi ) retreat into cool burrows as the sediment surface gets warmer (Munguia et al, 2017), but this prevents courtship display and mating, which can only happen on the surface (Darnell et al, 2020).…”

Dehydration risk is associated with reduced nest attendance and hatching success in a cooperatively breeding bird, the southern pied babbler Turdoides bicolor

“…Many studies have considered the impacts of climate variability and change on birds ( Dunn and Møller, 2019 ; McKechnie, 2019 ; Pearce-Higgins and Green, 2014 ). Impacts directly attributable to adverse weather and changing climate regimes include higher risk of mortality ( Bourne et al , 2020b ; McKechnie and Wolf, 2010 ; Sharpe et al , 2019 ), reduced breeding success ( Bourne et al , 2020a ; Conrey et al , 2016 ; Cruz-McDonnell and Wolf, 2016 ; Cunningham et al , 2013 ; Skagen and Yackel Adams, 2012 ), compromised body condition and immunocompetence ( du Plessis et al , 2012 ; Edwards et al , 2015 ; Gardner et al , 2018 ; Wingfield et al , 2017 ; Xie et al , 2017 ), declining populations ( Riddell et al , 2019 ; Saino et al , 2011 ), range changes ( Hockey et al , 2011 ; Huntley, 2019 ) and potentially maladaptive behavioural adjustments to foraging ( Bladon et al , 2019 ; Cooper et al , 2019 ; Cunningham et al , 2015 , 2021 ; Funghi et al , 2019 ; Pattinson and Smit, 2017 ), parental care ( Bourne et al , 2021 ; Carroll et al , 2018 ; Clauser and McRae, 2017 ; van de Ven, 2017 ; Wiley and Ridley, 2016 ) and migration ( Dunn et al , 2010 ; Samplonius et al , 2018 ).…”

A summer and winter’s tale: factors influencing avian community composition and species abundances in lowland subtropical floodplain forests in central eastern Australia

“…The former favour choices that optimise energy and nutrient input, and the latter reflects survival (Frid and Dill 2002;Cooper and Frederick 2007). Those factors set the feeding strategies and choices made by species into a framework of risk and trade-offs (Wilson et al 2020;Cunningham et al 2021). The extent to which human activities are perceived by animals as a threat influences their reaction to humans as potential predators (Price 2008;LaManna and Martin 2016;Gaynor et al 2019).…”