High temperatures drive offspring mortality in a cooperatively breeding bird

An improved understanding of life history responses to current
environmental variability is required to predict species-specific
responses to anthopogenic climate change. Previous research has suggested
that cooperation in social groups may buffer individuals against some of
the negative effects of unpredictable climates. We use a 15-year dataset
on a cooperative-breeding arid-zone bird, the southern pied babbler
Turdoides bicolor, to test i) whether environmental conditions and group
size correlate with survival of young during three development stages
(egg, nestling, fledgling), and ii) whether group size mitigates the
impacts of adverse environmental conditions on reproductive success.
Exposure to high mean daily maximum temperatures (mean Tmax) during early
development was associated with reduced survival probabilities of young in
all three development stages. No young survived when mean Tmax >
38°C across all group sizes. Low reproductive success at high temperatures
has broad implications for recruitment and population persistence in avian
communities given the rapid pace of advancing climate change. That impacts
of high temperatures were not moderated by group size, a somewhat
unexpected result given prevailing theories around the influence of
environmental uncertainty on the evolution of cooperation, suggests that
cooperative breeding strategies are unlikely to be advantageous in the
face of rapid anthropogenic climate change. An improved understanding of
life history responses to current environmental variability is required to
predict species-specific responses to anthopogenic climate change.
Previous research has suggested that cooperation in social groups may
buffer individuals against some of the negative effects of unpredictable
climates. We use a 15-year dataset on a cooperative-breeding arid-zone
bird, the southern pied babbler Turdoides bicolor, to test i) whether
environmental conditions and group size correlate with survival of young
during three development stages (egg, nestling, fledgling), and ii)
whether group size mitigates the impacts of adverse environmental
conditions on reproductive success. Exposure to high mean daily maximum
temperatures (mean Tmax) during early development was associated with
reduced survival probabilities of young in all three development stages.
No young survived when mean Tmax > 38°C across all group sizes. Low
reproductive success at high temperatures has broad implications for
recruitment and population persistence in avian communities given the
rapid pace of advancing climate change. That impacts of high temperatures
were not moderated by group size, a somewhat unexpected result given
prevailing theories around the influence of environmental uncertainty on
the evolution of cooperation, suggests that cooperative breeding
strategies are unlikely to be advantageous in the face of rapid
anthropogenic climate change.