Back in 2018, 28 new Swift nest sites were created in the eaves of Lymington Business Centre where there is an existing colony of Swifts. The new boxes were fixed on the north and east sides which have slated walls.
Birds were seen entering at 13 sites this year. Numbers have varied between 9 and 16 pairs over the last seven years (excluding 2020 when surveying was affected by Covid restrictions). This year, for just the second time, birds were seen entering and exiting one of the boxes. The reason why there has been no wholesale take-up of the boxes, as was expected, is unclear, but it may be because we decided at the time to install the entrances at right angles to the building rather than flush with wall surface. I think now that that was the wrong decision as it makes it more difficult for birds to accurately enter the entrance hole(30x65mm) which would be more difficult if there is a breeze. It gives them no flat vertical surface on which to place their feet to guide their way in through the entrance.
We know that Swifts can and do enter a hole in a soffit where a 70mm airvent has dropped out or where a larger drain vent pipe has been removed and the hole in the soffit has not been repaired, but that larger hole size gives them a bit more ‘tolerance’. You wouldn’t want to get it wrong and hit a solid surface with you head at 40mph!
The options would appear to be:
• Provide a vertical landing strip on one side of the hole (we would need to know the usual approach direction of the birds).
• Replace the soffit of each box with the hole flush against the slate wall.
• Increase the size of the hole to 70 or 100mm.
The latter would appear to be the simplest option but we’ll give it some thought.
You can read Bob Lord’s excellent full report in detail here.
Comments