2025 Hertfordshire Swift Nest Survey
Graham Knight
Dear all,
It is finally time to share a short summary of the results of our nest survey from last year:
The survey recorded a total of 1082 Swift nests in the county in 2025, with 96 of these (8.87%) being in Swift boxes or bricks.
The survey results are largely due to collaboration between several Swift groups, who undertook many hundreds of hours of survey work, both using the traditional survey method where observations take place of Swifts entering and exiting nest sites, and the “call and response” method which is best used early in the morning. At least 450 of the nest records were found by call and response.
Three towns reached the milestone of joining the “100 club”: Hertford (144 nests), Hitchin (118 nests) and Bishop’s Stortford (100 nests), the latter being home to the fabulous colony at Redwood Court which recorded a minimum of 47 nests in a single building.
Further, the East Herts District Council area (which includes Hertford, Ware and Bishop’s Stortford) recorded 462 nests as a result of a large amount of survey work. The detailed records from this area, which include precise nest locations, allow us to compare with previous years: it appears that at least 285 of the 355 East Herts nests recorded in 2024 were again occupied in 2025, a minimum return rate of 80%. The actual rate is likely to be higher, with some nests probably missed and a few not checked in 2025.
The map and table show the Swift hotspots – however we are of the view that there are a lot more Swift nests to be found, and that considerably less than half of the Swift nests have been recorded this year.
This is because although records have come from all over the county, intensive survey work has not been carried out in many towns, especially in the western and southern parts of Hertfordshire – and no evening surveys have been done in many areas. For example, Watford is the largest town in the county but only 6 hours of survey work took place, resulting in 18 nests being found.
This leads us to the conclusion that the actual county Swift population is at least in the region of 2500 to 3000 pairs, if not higher. We also believe that if survey work were to be carried out intensively in other counties, far more nests would be found than suspected, and that the national population is considerably greater than official estimates.
It is hoped that the number of Swifts using bricks and boxes will continue to increase in future years and that this will help to stabilise the county population.
My personal takeaways from this: the more you survey for Swift nests, the more you will find, and there are always more Swift nests than you think there are.
Many thanks to everyone who told us about Swift nest sites, and in particular the following who all put in many hours of hard work: Clive and Helen Fleming (Hertford Swift Group) Gavin Vicary (North East Herts Swift Group), Jayne Topping (Ware Swifts & House Martins) and Dean Cornish and Helen Matthews (Hitchin Swift Action). Particular thanks to Dean for the map as well.
Roll on 2026!
Best wishes
Graham Knight
