Scientists of the University of North Carolina have published the results of a citizen science programme called eBird, in which amateur birdwatchers have helped to collect data on bird numbers in the US, creating a database that shows frequency of occurrence for various bird species for given locations and dates.

From this database bird migration patterns can be established – for instance the route migratory birds take and the spring arrival of birds from the south, and the autumn arrival of birds from the north.

Since 2002 48 million bird observations from some 35,000 contributors were added to the eBird database. Indeed, the word amateur is hardly fitting, if you what true birdwatchers can be like.

The researchers who analysed the data – and just published their results in PLoS ONE – have focused on the spring arrival dates for 18 different species of birds in the eastern half of the US (including the red-eyed vireo, the scarlet tanager, the great-crested flycatcher and the indigo bunting) and find some seem to adapt more rapidly to a changing climate – or to be more precise: to a time shift in the onset of seasonally normal temperatures.

Less than a week before schedule – so far

The fast adapters on average arrived 3-6 days earlier for each degree Celsius of warming. That may not seem much, but especially in the northeastern states that one degree warming has already been surpassed. The authors think under continued warming the migratory birds in the Atlantic USA could get into serious trouble in 50-75 years.

Because of regional differences in the expected climatic changes, these could also affect the migratory routes birds take, possibly putting a greater strain on individual species. Changes in bird’s migratory routes are also observed under ENSO climatic fluctuations.

But what about the other species?

The fact that some species are quicker to adapt to climate change than others is in fact an ecological concern in itself. That is because species don’t live autonomously [as we humans commonly perceive our own existence on this planet] but rather form an intricate part of respective ecosystems. In Europe birdwatchers have for instance noted that the breeding behaviour of some great tit populations [those in the Netherlands, not those in the UK – these seem to differ genetically, and adapt faster to warming] does not correspond well with the earlier onset of spring temperatures, which leads to an ever-earlier caterpillar peak, that the young tits depend on.

The University of North Carolina researchers hope their study will increase awareness around bird conservation – and possibly help identify which species will be most threatened under continued climate change.

Changing migration patterns are not just a concern in the air, also on land and in the oceans forced migrations may the most important climate-induced contributor to biodiversity loss.

© Rolf Schuttenhelm | www.bitsofscience.org