~ Longevity & Site Fidelity ~
Ringers often consider retrapped birds as being the “poor relations” during the a day’s ringing, but these retraps provide us with the individual bird’s unique history.
Sometimes a particular bird will only be caught in a certain month of the year for several consecutive years. This indicates the bird is using Stanford as a stopping off point during its annual migration between countries or, if it is a resident UK species, during local movement. A good example of this is a Willow Warbler (1W8238). Originally ringed as a juvenile in Cambridgeshire (July1994), retrapped the following year in Sussex and then trapped only once or twice at Stanford in each of several consecutive years (1998 -2001) during the Spring migration period.
Some birds resident at Stanford throughout the year will be retrapped many times throughout their life and we have several instances of such birds being retrapped over twenty times with one particular Dunnock (R181637) having been trapped on some thirty occasions over a six year period. We have several examples of long lived birds (illustrating faithfulness to a site - site fidelity, as well as old age). Two examples of migrants are -
Stanford Reservoir currently holds the UK and European record for longevity of three species -