The first twenty are in! But how do this year’s arrival dates compare with those of previous years?
A review of how spring is progressing, in terms of the arrival of summer visitors, covers the five weeks up to 9th April. Two species, Blackcap and Chiffchaff, are excluded as both have significant wintering populations that cloud the arrival dates of those wintering outside of the UK.
This year, one species sets a new record for the earliest ever arrival date. The Garden Warbler at Boddington Reservoir on 7th beats the previous earliest, which was in 2010, by three days. This year’s Common Whitethroat and Willow Warbler are relatively early for the county, being only three days and seven days later than the earliest, in 1998 and 1997, respectively. No other species produced noteworthy arrival dates, especially when population dynamics are taken into consideration.
With another fifteen species to arrive over the next five weeks or so it will be interesting to see if they are on time, early, or late. An expanded list of general migrant arrival and departure dates, including historical extremes, is published annually in the Northamptonshire Bird Report.