[INFORMATIVE] Migratory Mayhem: How the climate crisis impacts avian species

Migratory Mayhem: How the climate crisis impacts avian species

Leah Mari Li

Migratory birds, with their iconic V formation, have long been important symbols of faith, fortune, and freedom. Their long and arduous journeys, stretching across continents, have been a source of fascination and inspiration for many. Their disappearance would undoubtedly leave a gaping hole in our skies, but how does climate change threaten these avian travelers? As rising temperatures, shifting seasons, and habitat loss disrupt their migratory patterns, the survival of these birds is increasingly at risk. This article explores the profound impact of climate change on migratory birds, highlighting the urgent need for conservation efforts.

Free as a bird
Migratory birds are species that, contrary to non-migratory birds or resident birds, leave their breeding grounds and spend the winters in warmer regions. These migrations typically occur from north to south, as many migratory species, mostly insectivores, struggle to find enough food once breeding seasons are over. Other motivations include reduced exposure to predators or pests, warmer weather, and longer daylight hours. One common example of this behavior is the common nightingale, which spends the warmer seasons in Europe before migrating to Sub-Saharan Africa. However, these flight routes vary from species to species.

What has long fascinated researchers and bird enthusiasts is how migratory birds can successfully navigate their way across continents with such impressive accuracy. But how do they exactly do it? One method involves following environmental cues like the position of the stars and the sun. Remarkably, due to their ability to perceive UV light, they can even navigate when the sky is cloudy. The other method, which is particularly intriguing for scientists, is their use of an internal compass to determine their angle towards the Earth's magnetic field. Surprisingly, it was also discovered that even animals raised in isolation knew exactly where they needed to go.

Similar to these internal compasses, migratory birds also use internal clocks that help them determine when it’s time to move into the skies for their next destination. In addition, shorter day lengths as well as different food supplies can stimulate hormones and trigger their instinct to migrate. However, this is also when their hardships begin.

The early bird catches the worm?
Migratory birds rely on various cues in their environment to determine when to leave their breeding grounds, when to molt, and when to fatten up for their long and arduous journey, some spanning over 25,000 miles.

However, climate change is disrupting these carefully tuned schedules. Precipitation patterns and seasonal timings are changing all across the globe: spring is arriving two weeks earlier on average, and autumn is lasting two weeks longer. While some birds try to adapt, many species simply cannot keep up with these rapid changes. For instance, whooping cranes arrive 22 days earlier at their breeding grounds and leave 21 days later in the fall compared to the 1940s. Unfortunately, not all species can adapt quickly enough, and their migratory behaviors, deeply ingrained in their genes, may take generations to adjust.

This leads to a serious risk of a timing mismatch. Migratory birds depend on the food sources brought by spring, such as flowers, leaves, and insects. As the abundance of these resources changes, birds may arrive too early or too late, disrupting their feeding and breeding cycles. The risk for a bird to arrive at the wrong time increases the further it has to migrate. For instance, the Arctic tern travels from the Arctic all the way to the Antarctic coast, facing complete uncertainty about the seasonal conditions on the other side of the world. Some species will also be at risk of a timing mismatch between the time for breeding and the time when prey are most abundant.

As if these challenges weren’t dramatic enough, climate change introduces more direct effects. Warmer winters can change or shorten migratory routes, or in some cases, result in a complete cancellation of the journey. Species like cranes or starlings decide to stay in Germany instead of flying to warmer countries like Spain or Portugal. Unfortunately, these birds are not accustomed to the colder winters, and many of them may not survive the temperatures. Moreover, birds that choose not to migrate start to compete with resident birds and might even become invasive species when settling in new habitats.

How to kill two birds with one stone (not literally)
A UN report reveals that about 44% of all migratory species are at risk of becoming extinct. Droughts and fires, intensified by extreme heat, destroy the habitats of many species. In addition, rising sea levels drown nests built in marshland areas, and rising temperatures increase the spread of various viruses and diseases, threatening the lives of many wild birds.

Resolving these problems requires complex solutions that target both the climate crisis and support the conservation of migratory birds. Effective strategies would be to preserve critical habitats, introduce crucial measures to reduce greenhouse gas emissions, and protect key breeding and stopover sites. It is crucial to combine existing initiatives, such as habitat restoration projects, with community-based efforts, such as local conservation programs. Only through collective action and commitment can we ensure a safe future for these remarkable travelers.


Sources:
Adams, A. (n.d.). Climate change and migratory birds. Worldmigratorybirdday.org. Retrieved August 18, 2024, from https://www.worldmigratorybirdday.org/2007/index44cb.html

al Conocimiento (Knowledge Window), V. (2024, May 10). How climate change affects bird migrations. OpenMind. https://www.bbvaopenmind.com/en/science/bioscience/how-climate-change-affects-bird-migrations/

Arctic migratory birds initiative (AMBI). (n.d.). CAFF. Retrieved August 18, 2024, from https://www.caff.is/work/projects/arctic-migratory-birds-initiative/

Burakoff, M. (2024, March 5). As spring shifts earlier, many migrating birds are struggling to keep up. Audubon. https://www.audubon.org/magazine/spring-shifts-earlier-many-migrating-birds-are-struggling-keep

Carey, C. (2009). The impacts of climate change on the annual cycles of birds. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 364(1534), 3321–3330. https://doi.org/10.1098/rstb.2009.0182

Kathryn. (2022, July 20). How does climate change impact birds? American Bird Conservancy. https://abcbirds.org/blog/climate-change-impact/

Larson, C. (2024, February 12). Nearly half of the world’s migratory species are in decline, UN report says. AP News. https://apnews.com/article/united-nations-report-migratory-species-decline-9068ad6e13c7f6ee57d6d92deef4646f

Major new UN report finds climate change is severely impacting Migratory Species of Wild Animals. (n.d.). Cms.int. Retrieved August 18, 2024, from https://www.cms.int/en/news/major-new-un-report-finds-climate-change-severely-impacting-migratory-species-wild-animals

Mitwirkenden, V. der. (n.d.-a). Laden Sie Arktis Seeschwalbe im Australien kostenlos herunter. Vecteezy. Retrieved August 18, 2024, from https://de.vecteezy.com/foto/25928593-arktis-seeschwalbe-im-australien

Mitwirkenden, V. der. (n.d.-b). Laden Sie fliegende Vögel bei Sonnenuntergang kostenlos herunter. Vecteezy. Retrieved August 18, 2024, from https://de.vecteezy.com/foto/1307643-fliegende-vogel-bei-sonnenuntergang

Powell, H. (2021, August 1). The basics of bird migration: How, why, and where. All About Birds. https://www.allaboutbirds.org/news/the-basics-how-why-and-where-of-bird-migration/To the ends of earth. (n.d.). Nationalgeographic.org. Retrieved August 18, 2024, from https://education.nationalgeographic.org/resource/ends-earth/