BirdTrack data reveals migrants' behaviour


Some of our most evocative summer visitors have been undergoing worrying declines in recent years and the factors behind these declines are not fully understood. In research published earlier this year, BirdTrack data from the Noughties were compared with data from the Inland Observation Points survey, a project run by the BTO in the 1960s. This revealed that 11 of 14 species studied have made a significant advance to their arrival dates. Swallow and House Martin are among six species that now arrive back more than 10 days earlier than previously. Four species, including Whinchat and Garden Warbler, are now leaving significantly later in the year. Intriguingly, most of the species which showed limited or no change to their arrival and departure dates are also those which have suffered the largest population declines.

Our recently launched BirdTrack Research Project will enable expert BTO researchers to find new ways to analyse millions of BirdTrack records to answer some of the most pressing questions about our summer migrants and help understand more about why they are disappearing. This important research will deliver fresh insights into bird population and distribution trends, habitat use and migration patterns across a range of species throughout the UK and beyond. Thanks to everyone who has donated so generously to the BirdTrack Appeal.

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You can further support this vital research by submitting your sightings to BirdTrack. The most valuable data are those submitted as complete lists, as these provide information about how frequently a species is being recorded at any point in the year and act as a robust measure of arrival and departures dates of migrants. All a complete list involves is a reasonable effort at covering your birding site and submitting a list of all birds you positively identified. While birders have been great at recording their first spring migrants on complete lists, there are fewer lists submitted in autumn. To this end, we need your complete lists to help get a more comprehensive picture of the departure dates of our summer visitors.

If you are out birding this autumn and have a smartphone, why not try out the new version of our app for Android and iOS?

Written by: Stephen McAvoy, BirdTrack Support Officer