Migrating Birds Struggle to Keep Up with the Weather
It is vital that wild birds return to our shores at the right time. Their arrival has to coincide with the appearance of food sources in order for them to feed themselves adequately and to care for their young. The birds spend the winter in warmer regions and then return to breed in the spring. Unfortunately climate change is causing spring to begin early and the birds are unable to speed up their returns so that they arrive on time.
New Research into Migration
New research suggests that birds are less adaptable to climate change that had been hoped. Spring has started to arrive 6-8 days earlier than it used to and scientists are discovering evidence that the birds are struggling to adjust to the new timetable. The problem could potentially affect half of all birds in the UK including geese, songbirds and raptors. Some species are showing signs of leaving their winter homes earlier but many are unable to perceive the shifts in temperature and still rely on the duration of daylight to tell them when to fly.
Upping the Pace
These birds would have to speed up their journeys in order to arrive at the right time. But how do they do that? The would not have sufficient energy to flap their wings any harder as they must travel such huge distances. A new study, published in Nature Climate Change suggests that they could reduce the length of their stopovers. These are the pit stops they make in order to rest and restore their energy levels before continuing with their journey.
Sadly the study has also revealed that reducing the stopovers by as much as 50% would only enable the birds to arrive two days earlier when they really need to arrive much earlier than that. The peak availability of caterpillars, for example, has advanced 20 days since 1980. There is an increasing disparity between the peak availability of food sources and the arrival of the birds and this could lead to serious declines in the number of birds in the UK.
To make matters worse, climate change could also impact the birds' stopover locations and so their rest stops might actually have to be longer in the future. It is possible that birds have failed to adapt to climate change because the change has been so rapid. Perhaps over time they will learn to adapt their migration patterns so that they arrive at their nesting grounds earlier in the year. That is if there are any birds left!