Donal Hickey: Will climate change alter the arrival of the cuckoo

Tracking their migration can help answer questions like the effects of recent weather on wildlife
Donal Hickey: Will climate change alter the arrival of the cuckoo

The cuckoo was first heard in Buttevant, Co Cork, on March 16, 2020, a month earlier than in Co Mayo, in 2021.

Every day, we see signs of the changing climate. Four years ago, on January 1, the Botanical Society of Britain and Ireland found 239 species flowering in the wild from counties Cork to Donegal, about 10 times more than 30 or 40 years previously.

All of which makes the study of phenology (the timing of annual cycles of plants and animals, as when a plant flowers, goes to seed and insects emerge from hibernation) extremely relevant.

Nature and wildlife are responding to climate change, but the rate of change is still not clearly understood. In a bid to learn more, the National Biodiversity Data Centre is asking people to help provide records for the first occurrence of nine seasonal events, such as the cuckoo’s date of arrival.

This information, to be included in the Farmer’s Wildlife Calendar, can help answer questions like the effects of recent weather on wildlife and how climate change is affecting timings in nature.

Comparisons between the years 2020 and 2021 are interesting. In 2020, we had a good spring, which resulted in seasonal events being first recorded earlier than in 2021 when we had a markedly poorer spring.

For instance, the cuckoo was heard in Ardskeagh, Buttevant, Co Cork, on March 16, 2020, a month earlier than in Co Mayo, in 2021.

Blackthorn was flowering in Goleen, Co Cork, on February 14, 2020, two days earlier than in Corbally, Limerick, the following year.

Most of our summer migrant birds don’t arrive until April or May, by which time the winter visitors, such as waders, have departed. A notable exception is the swallow, which has been coming in early March in
recent years.

Birds migrate for food and the correct breeding conditions. They need to find food at the right time of the year to allow them
rear their young. Insect-eating birds cannot survive here in winter because the cold sees off their main source of food.

During the summer months, however, there’s an abundance of insects and, with longer days giving birds more time to forage, they have the perfect combination for rearing their young.

This seemingly just-right coming together of events is the result of millions of years of evolution. However, as the National Biodiversity Data Centre says, with our climate changing rapidly, such events may move out of sync and put nature at risk. If insect-eaters come too early, they could be short of food, for example. All about timing!

Meanwhile, we await the first swallows, due in a month or so.

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