The dates at which nestling birds were historically ringed with metal bird rings by volunteer bird ringers yields information about the timing of breeding seasons. The current dataset consists of ringing data of nestling birds from the period 1911-1959. Each record lists one individual ringed bird with the unique ring number, the date the bird was ringed, the geographical name of the locality and the geographical coordinates (WGS84). Information about the nestlings age and brood size may also be present. 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 2016.