How climate change is affecting migratory birds

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How climate change is affecting migratory birds

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Being a bird sounds amazing. Well, you only need to wake up, feed, find a mate, rest and let the universe continue with or without you. This is the cycle of life. From an ecological perspective, the most important habitual characteristics of animals are to eat, breed and survive. Humans, in most cases, when the day ends, we are glad to have made it through and when the morning comes, it’s a new day to be the best versions of ourselves, all over again, but this time different than our yesterday.  The non-human being faces fewer challenges than us. Especially in areas where there is no human interference. Humans have made it difficult for species in the non-human world, who could do well without us, to survive. Most have adapted to our existence but for some…well, this commentary says it all.

Let’s consider a migratory bird considering we just marked World Migratory Bird Day, this weekend. This event is observed every 2nd weekend of May every year. In this scenario, let’s pick the Thrush Nightingale, Luscinia luscinia. Also known as sprosser.

The Thrush Nightingale breeding ground stretches from northern and eastern Europe to western Siberia. During the non-breeding season, it heads south through the Sahara Desert to Ethiopia through Kenya and Tanzania to Zambia and southern Africa. It departs from its breeding grounds in early August, eventually getting to southern Africa around late December-January, making it one of the latest arriving migrants recorded in the region. This occurs during the winter period in Europe and Siberia since the cold temperatures will be too much for the species and others of its kind to stand the harsh winter weather. This behaviour, by the way, is called overwintering. Sprosser mainly departs in late March, eventually arriving at its breeding grounds in the period from late April to mid-May.

Between Europe/Siberia and Zambia, this is a ‘short’ trip on a physical map but in actual sense, it is more than a 10-hour flight for migratory birds, even though our mechanical birds have made it easier for humans to mimic birds. Imagine having to fly (you have wings) from Russia to Kenya, passing through all the geographical boundaries that ensure we remain as civilized nations. Flying through all the man-made dismay civilized nations have created to live ‘better’ lives. So we think. From buildings to wind vanes and the occasional gunshots stripping the air proofing that light is faster than sound. Where pristine forests have become concrete jungles that even choosing to rest might place you (a migratory bird) at risk of not finding a safe place to rest or even feed.

Climate change has not made things any easier. This is because the climatic conditions are today not as predictable as their ancestors were accustomed to. Phenologically, there is limited food and sometimes time to build fat reserves. In some instances, breeding when there is plenty of food becomes a big hustle because of limited resources. This results in population decline for migratory bird species in areas with a late food peak as breeding is now not guaranteed. Even though studies have identified magnetic cues alert migratory birds to build fat reserves, what happens when there is no food (arthropods and small, soft berries)?

As ecological processes continue to change in repose to climate warming, migratory birds have been documented to arrive and breed early when it is Spring or leave late during Winter. Migratory birds can be affected by shifts in global climate patterns. In the African region, insect abundance and vegetation cover vary greatly between seasons. There are plenty of insects peaking during the rainy season which drops in abundance during the following dry periods. If a Sprosser landed in Kenya this year, the first few months of 2018 experienced very harsh dry weather which was followed by heavy rains beginning March.

Climate change has a longer timescale compared to natural disasters such as volcanic eruptions, habitat destruction (change in land use), air and water pollution and invasive animal and plant species, which could affect the pathway or ecological setting of a migratory bird. When we look at 20 – 50 years from today, the effects of climate change are likely to become increasingly noticeable relative to the other factors.

Effects of climate change include shifts in species’ geographical range which is a result of a shift in the normal patterns of temperatures and humidity that will restrict species boundaries. A 1 °C rise or drop in temperature moves ecological zones on Earth by about 160 km.

Higher temperatures are most likely to be accompanied by more humid, wetter conditions, but the geographical and seasonal distribution of precipitation will change. The ability of species to respond to climate change depends on migratory bird species’ ability to ‘monitor’ shifting climate which could lead to colonizing new territory or modifying their physiology and seasonal behaviour, before and during migration, to adapt to the changed conditions where they are. This seems easy, but, animals do not adapt as easily as we might think. It takes time. Time, which could lead to the extinction of migratory bird species that are already on the endangered species list. We can only choose to act because climate change is today not a naturally occurring process but a human-caused extinction accelerator.

Climate Change stands on its own in the Sustainable Development Goals in SDG goal 13 as Climate Action. With this, one of the goal targets is integrating climate change measures into national policies, strategies and planning. Kenya, through the Ministry of Environment and Forestry, seeks to restore water towers and green zones through ongoing afforestation campaigns. This will, fortunately, provide a safe haven for migratory birds when they land, not immediately, but in the coming years. For now, responsible actions throughout the world, especially in countries that are migratory routes for migratory bird species, action needs to be taken to mitigate climate change while ensuring birds do not stop in the middle of their journey without getting to their final destination. Birds are great ecological indicators, and when we begin to observe migratory birds with less fat reserves plus delayed arrival, then we know the state of the earth may not be that favourable for all of us.

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Vicki Wangui
Vicki Wangui
Vicki Wangui is a believer in all things beautiful. A believer in spreading information in regards to environmental awareness. A believer in sharing all that is good in Kenya's natural world. A believer in speaking truth with no boundaries. Do you have a story, photo, experience or message you need to share? Send your work to

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