Birth rate of large, migratory birds declined due to climate change

Subject :Environment

Section: Climate change

Context: Study shows declines in offspring production were observed in relatively large birds & migratory birds.

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Climate change has reduced the overall birth rate of bird species across the world, a new study has found.
Researchers analysed 201 wild bird populations from all continents between 1970 and 2019 and found birth rate has declined during recent decades, with great variation among species and populations.
Declines in offspring production were observed in relatively large birds and migratory birds, whereas species whose production increased were small-bodied and sedentary.
The research suggested that larger species were more vulnerable to declines in offspring production. Body mass exceeding one kilogram for sedentary species and 50 grams for migratory species is associated with adverse trends in offspring production.
Larger-bodied species may respond slower to changing environmental and climatic conditions due to their lower fecundity (ability to produce young) and extended maturation period.
Thus, climate variability is an important factor when coupled with migratory habits and the number of broods raised in the breeding season.
The researchers found that non-migratory species, especially smaller ones, can usually adjust to changes in local conditions and may benefit from climate warming. While migratory species, except the smallest, may suffer.
The study aimed to look at the temporal changes in annual offspring production by female breeders in relation to changes in local temperatures and species’ life history traits.