The dates at which nestling birds were historically ringed by volunteer ringers yields information about the timing of breeding seasons. The current dataset consists of ringing data of nestling birds over the period 1911-1959. Fieldnames are largely self-explanatory, data follows the EURING 2000+ code. For a detailed explanation and preferred citation, see the link in the field 'Relation', below, or paste the following URL in your browser http://www.euring.org/data_and_codes/euring_code_list/euring_exchange-code_2000.pdf . The dataset consisted of 157.978 records at 14-2-2014. More data will be added during 2014 and 2015.