Latitude-specific responses of European birds’ population growth rates to temperature and water availability

Climate limits the distribution of species and varies along a latitudinal
gradient. However, studies relating climate variation to species
population growth rates in different climatic zones while taking into
account species’ ecological traits are scarce. We assessed species
population responses to the main climatic constraints at a continental
scale by studying how precipitation and temperature at different latitudes
influence interannual growth rates while considering species’ life-history
traits. We gathered data on the abundance of 141 European breeding bird
species from national breeding bird monitoring schemes in the
Mediterranean (Catalonia, NE Spain), temperate (Czech Republic), and
boreal (Sweden) climatic zones for the period 2002–2022. We used
generalized linear models to relate the interannual population growth
rates of bird species to spring and winter temperature, water availability
and heavy rainfall in the breeding season. We considered migration
strategy as a covariate possibly shaping bird responses to climate. We
found general positive effects of spring and winter temperatures and water
availability, and negative effects of heavy rainfall. Increased
temperatures affected residents more positively in southern Boreal than in
continental and Mediterranean climatic zones. Long-distance migrants
responded negatively to temperatures in continental and northern Boreal
zones. Higher water availability supported residents and short-distance
migrant populations more in lower and higher latitudes than in
mid-latitudes. Heavy rainfall tended to affect birds, especially
residents, more negatively towards the north, where we revealed the
strongest effect among the considered climate variables. Similarly,
short-distance migrants suffered more from the intensive rains in northern
Boreal than in other climatic zones. Previously, temperature has been
shown to be a strong climatic constraint of bird population dynamics. Our
results suggest that future changes in precipitation regimes during the
birds’ breeding season should also be considered among the important
climatic pressures on bird population growth rates in different climatic
regions.