The effect of nest temperature on growth and survival in juvenile Great Tits Parus major

Abstract

For birds, maintaining an optimal nest temperature is critical for early‐life growth and development. Temperatures deviating from this optimum can affect nestling growth and fledging success with potential consequences on survival and lifetime reproductive success. It is therefore particularly important to understand these effects in relation to projected temperature changes associated with climate change. Targets set by the 2015 Paris Agreement aim to limit temperature increases to 2°C, and, with this in mind, we carried out an experiment in 2017 and 2018 where we applied a treatment that increased Great Tit Parus major nest temperature by approximately this magnitude (achieving an increase of 1.6°C, relative to the control) during the period from hatching to fledging to estimate how small temperature differences might affect nestling body size and weight at fledging and fledging success. We recorded hatching and fledging success and measured skeletal size (tarsus length) and body mass at days 5, 7, 10, and 15 posthatch in nestlings from two groups of nest boxes: control and heated (+1.6°C). Our results show that nestlings in heated nest boxes were 1.6% smaller in skeletal size at fledging than those in the cooler control nests, indicating lower growth rates in heated boxes, and that their weight was, in addition, 3.3% lower. These results suggest that even fairly small changes in temperature can influence phenotype and postfledging survival in cavity‐nesting birds. This has the potential to affect the population dynamics of these birds in the face of ongoing climatic change, as individuals of reduced size in colder winters may suffer from decreased fitness.

Experimental nest cooling reveals dramatic effects of heatwaves on reproduction in a Mediterranean bird of prey

“…This finding is in line with previous studies on both wild bird species (Andreasson et al, 2018;Corregidor-Castro & Jones, 2021;Rodriguez & Barba, 2016;Shipley et al, 2022;van de Ven et al, 2020) and poultry (Nawaz et al, 2021). Two non-mutually exclusive mechanisms may explain the impaired growth in nestlings exposed to elevated T nest .…”

Extreme hot weather has stronger impacts on avian reproduction in forests than in cities

“…Additionally, during heat stress, evaporative water loss is elevated as the organism tries to cool itself by evaporation to maintain body temperature in the physiologically normal range, causing dehydration [44,45]. Thus, increased metabolic rate and water loss both can lead to decreased body mass, as it has been shown in several bird species [16,[46][47][48].…”

Extreme Hot Weather Has Stronger Impacts on Avian Reproduction in Forests Than in Cities

“…Additionally, during heat stress, evaporative water loss is elevated as the organism tries to cool itself by evaporation to maintain body temperature in the physiologically normal range, causing dehydration (Weathers, 1972;Arad et al, 1989). Thus, increased metabolic rate and water loss both can lead to decreased body mass, as it has been shown in several bird species (Quinteiro-Filho et al, 2010;Kruuk et al, 2015;Corregidor-Castro and Jones, 2021;Oswald et al, 2021). Although parents can help their nestlings thermoregulate, great tits cannot shade their nest-boxes and they are not known to be able to cool their nestlings in other ways such as providing water.…”