A warbler is weighed at a ringing hut on a private reserve in East Sussex, Rye, UK. The British Trust for Ornithology is in the process of recording migrating hirundines and other birds at the reserve. Hirundines comprise of Sand Martins, House Martins and Swallows, all of which roost in high numbers on the reserve over summer before continuing their migratory route back to Africa. The information gathered, including age, weight and sex, allows the BTO to monitor long-term population and global migration patterns, which is important for conservation
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