IRISH PHENOLOGICAL OBSERVATIONS FROM THE EARLY 20TH CENTURY REVEAL A STRONG RESPONSE TO TEMPERATURE

Abstract

Phenology, the study of the timing of recurring life cycle events, has gained global scientific recognition in recent years as it demonstrates how ecosystems are responding to climate change. However, in Ireland the systematic recording of phenological events has not been traditionally undertaken. Here we present some recently rediscovered historic phenological records, abstracted from the Irish Naturalists' Journal for the period 1927-1947 (with a gap from 1940 to 1945) and analyse them with respect to temperature data, sourced from Dr Tim Mitchell's Tyndall Centre webpage. We find that in many cases in Ireland spring phenological events, such as first flowering, first leafing and first observations of insects, show an earlier trend in response to increasing spring temperatures over the study period. In addition, we compare spring migrant bird arrival dates from the Irish Naturalists' Journal records with those abstracted from various published and unpublished bird records from the eastern region of Ireland for the period 1969-1999. We demonstrate that five out of the seven species analysed were recorded earlier in the more recent time period, and three of these were significantly earlier. These results illustrate the value of historic phenological data records for investigating and comparing past and present climate influences on species developmental behaviour.