Heathfiedl Starling Roost

21st February 2018:  An estimated 20-25,000 into roost.  This was my first visit to the site and is a much higher estimate than the 7,000 or so quoted by several people.  I may have over-estimated and was sussing the site out as part of a wider study in South Devon.  I have had considerable experience estimating large flocks as a regular WeBS counter on the Mersey Estuary for 15 years and  have been monitoring the Starling roost at Slapton on an almost daily basis for the last 6 years and a roost (in bamboo - shades of South Brent) at Ashprington which began in early December 2017 and has now finished.

Estimating at Slapton can  be done by estimating individual flocks as they arrive making an overall estimate more accurate - none come in from the sea!  However, both the Ashprington and Heathfield roosts are less easy to use this technique as there is no overall view from all directions that birds could be coming from.  However, it would be possible to estimate birds coming into Heathfield from the Dartmoor direction although clearly that is primarily because of where the roost is generally viewed from.  It is well known that people tend to under count such large roosts/flocks but I may have lost my touch!

It is possible that there were more birds tonight at Highfield ahead of the arctic airstreams over Scandinavia & the Continent and that over the North Atlantic coalescing  over the UK.  Numbers at Slapton fluctuate depending on weather conditions and always peak ahead of cold northerly airstreams dipping again as the cold spell hits the UK only to rise again ahead of the next cold airstream.  Birds are clearly migrating through Slapton in a similar way to Wood Pigeons and finches  and possibly follow the south coast in a similar way after breaking off from the main flyway down the Danish, Dutch, French coast and crossing the English Channel at Dungeness.  Work is currently in hand to see if there is evidence for this from datasets held by British south coast county ornithological societies and Scandinavian/European datasets, particularly long term datasets from Falsterbo and Ottenby in Sweden.  There clearly seems to be a correlation with data from Dungeness BO.

The Slapton roost has regularly been used for at least 213 years and, in recent times, always finishes before Christmas (although extending into mid- January in two of the last three years and showing changes in behaviour, particularly in relation to site fidelity within the Slapton reed beds depending on weather conditions and the need for greater shelter, possibly as a result of climate change).  I would be interested in meeting anyone who regularly counts the Highfield roost to see if data from there may be of use to this study as well as to see if I have lost my touch (!) although I'm pretty clear there were more than 7,000 tonight.

Posted February 21st, 2018 at 8:10 pm by Dennis Elphick in Scarce / Rare Birds & Passage Counts