Effects of Climate Change on Birds

Climate change is a critical issue around the world as it is disturbing all aspects of our environment. Along with other biotic factors, it is also disturbing animal wildlife. Birds are especially one of the classes of kingdom Animalia which is greatly affected by this climate change in a variety of ways. In this article, I am discussing the various effects of climate change on birds and how it is disrupting their habitats and endangering their populations. Birds are increasingly being affected by the changes in climatic patterns in terms of their habitats, migration, egg laying, and physical appearances.

On analyzing the data of the birds collected over the years, it has been seen that the birds are now changing their habitats due to global warming. Some of the birds of North America are shifting northward over time. The 90 years of Christmas Bird Count data suggest that as compared to a few decades earlier, some of the birds are expected to be found farther North. These birds include Woodpeckers and birds of prey such as Hawks along with other sub-tropical and desert area birds like Green Jay and Black-tailed Gnatcatcher among 70 different bird species.

Migratory birds are also showing changed patterns of their annual migration over the decades. One of the reasons for migration is that food is not available in indigenous habitats during winter seasons. Other factors include temperature changes, fewer daylight hours, and instinctive behavior in them. This means that each year they migrate from nesting grounds in the north towards the overwintering areas in the south mainly due to food, moderate climate, and more survival probability in the south. A study by the scientists of the Dept. of Bioscience at Durham University tells that several species of trans-Saharan migratory birds have reduced their stay up to 50-60 days in their African non-breeding or overwintering grounds. To study changes in arrival and departure dates over time, the research team used data on bird records collected by ornithologists in The Gambia (collected between 1964 and 2019) and The Gibraltar Ornithological & Natural History Society (collected between 1991 and 2018). The team found that the birds were leaving for winter destinations in the autumn later and coming back to their breeding grounds in spring earlier than before. They connected the observed changes to alterations in the vegetation and climate changes as the relatively cold temperature in the North is now becoming favorable for these birds to spend more time of the year in that part. It has been seen in Nightingales and Willow Warblers as they are now spending longer time in European breeding grounds, so some ornithologists have now started thinking that if the climatic conditions continue to change like these, the winter migration of birds might eventually come to an end.

An interesting migration pattern is studied in the recent research on the bird named Richard's pipits. Normally, the birds show migration patterns in such a way that they spend their breeding season in the North and the winter season in the South, this particular bird breeds in Siberia and used to overwinter in Southern Asia. But the recent research published in Current Biology tells that Richard's pipit is seen to overwinter in southern Europe in recent years in such a way that it flies from East to West rather than following its traditional migratory path that is North to South. They associated this change in migratory behavior with the change in climate such that these parts of Europe are now suitable for birds to overwinter.

There has also been seen that this change in climate followed by altered migratory patterns has resulted in the changes in body shapes of some of the birds. Brian Weeks, an assistant professor at the University of Michigan, Zimova, and other co-authors of a paper that was published in Ecology Letters in 2020 took data from the dataset on body size and wing length for species including dark-eyed juncos and white-throated sparrows. They discovered that, on average, wings grew longer and bodies smaller over 40 years. They discovered a similar trend when they combined this with climatic data. Rapid warming of temperature is followed by decrease in body size. They have also seen that these birds are departing for their breeding grounds earlier and late migrants are flying later than they did 40 years ago. These experts have connected this change in migration patterns with the change in their morphology. They predicted that the increase in the length of the wings is associated with more efficient and faster flights, so the species that have evolved the longer wings are the ones who reach their breeding grounds earlier.

Apart from these more scientific and evolutionary impacts, birds are being affected by climate change in some other ways also. In the wood fires due to global warming, birds are among the vulnerable community of animals which are greatly affected as their habitats are destroyed. The rise in sea level is affecting the birds that make their nests and reside along the coasts like Saltmarsh sparrows. Some diseases are associated with warmer climates and droughts. Droughts due to warmer temperatures lead birds to stay near water bodies and make a way for mosquito-borne infections.