General comments: As a resident, this species is probably quite local, but in most years, primary immigrants from Europe boost numbers and render the species more or less ubiquitous.
The text books inform us that there are fresh influxes of primary immigrants in most years. Based on the sudden appearance of large numbers on the same dates that other immigrant species appear, this appears to hold true in Hertfordshire. However, it is clear that not all reports can be explained this conveniently and it is evident that some primary immigrants must establish localised breeding populations. Unfortunately, almost every record we have for this species relates to an adult; it is unclear if the species is a permanent resident or just a temporary one - unable to survive the winter here and so dependent upon fresh immigration each year.
Recorded in 36 (88%) of 41 10k Squares. First Recorded in 1834. Last Recorded in 2023. Additional Stats
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