Monday, 4 March 2013

Conclusion of winter atlas

Most activity in the final week was owling, as local atlas fieldwork concluded after 6 years. Could not have asked for better weather, full moon and final two nights could have heard a pin drop at times. Highlights - finally getting Tawnys at Kamehill/East Fortoun (NT57U) and in Craigs Wood, Dirleton (NT58B). At former site (failed stake-out last weekend) tried 3 hours before dawn in ideal conditions, got an immediate response to my hoot from south of Kamehill, which then prompted reply from woods S of East Fortoun - nothing better to get owls calling than another owl! Moved on to the Dirleton site, this was approximately the 10th visit, and Jim had been at dusk the previous evening again drawing a blank - on arrival before having chance to generate any hoots heard a vocal pair moving throo the wood from the west, and at least one more in kewick call further N in Archerfield.

Early on final evening first went to Amisfield Park by Haddington, some ideal habitat around the walled garden but negative on Tawny. Did flush a Woodcock, and soon after had a proper roding sneeze note - not proper evidence of breeding interest but with eggs often laid in March* so roding must often commence in February. Later that evening went back to Ormiston area - on the minor road west out of the village under again ideal completely calm conditions immediately got distant wailing Tawny hoots from direction of Ormiston Hall, then replies from Cousland Park - the former approx one mile distant, the latter one mile from the first and about 1km from me. Magic to hear their exchanges in the dark and to appreciate they will probably have all their neighbours mapped out and known from these types of conversations - Tawny calls apparently can be recognised to individual bird even by humans. Also got Oyc tick near there at Caerlaverock Farm and Wolfstar, the latter a 10km tick for NT46 previously looked for when BTO Atlas was concluding, not that this matters any more. Moved on to Fountainhall near Pencaitland (NT46I) and on arrival a Tawny in SW corner of the Big Wood was giving loud kewick calls, obviously as alarm at arrival of car/light at this remote spot. So the final winter atlas tick at 10 minutes to midnight, a reminder that our coverage will remain incomplete - there presumably have been owls resident there throughout the 6 years of fieldwork!

Together with third party reports concluded with 7 more Tawny additions this week taking total to 21, the latest map now as per above (10+ Borders records updated 5/3). So we have c. 86 Tawny Owl presence records in interconnected tetrads in northern East Lothian, with just 14 blanks in a block of 100 tetrads, all but two of which (NT46T Saltoun Forest, NT67J Fir Links Wood) have <5% mapped wooded area (now indicated by X on map) - though even in these we have reports of their occasional or regular presence (NT58G, NT57J) so they will surely occur in all tetrads from time to time. Did not have time to really get anywhere beyond this area, which is effectively only about a half of East Lothian, in turn a third of Lothian, in turn a third of South-east Scotland area - so this area of more intense coverage is roughly just 5% of the total tetrads in South-east Scotland Atlas (1770). Thus it does not assist much with the regional species map but it does provide useful evidence on local status.

At the end of the project I realise how poor was my strategy for owling at the start, and more as a note to self I summarise some of the main rules:

  • Weather is key, if at all possible choose a calm night when your audible range extends dramatically, moreover the owls may be more inclined to communicate with one another. They presumably also hunt much more successfully when calm so might have more time for social interaction.
  • Timing is also very important - Tawnys will often call around dusk, sometimes before sunset but especially in the first hour after, when they start getting active; but in the mood they can be calling at any time of the night, also occasionally by day.
  • Watch out for noise interference; at sites near roads dusk visits can be poor due to traffic noise, thus try same very late or towards dawn; any rain can have a very bad impact on audibility due to drips on leaves, strong wind is worse; the dawn chorus, and dusk quivalent, can be a significant problem from late January, particularly Song Thrush and Robin singing in the hour after dusk can make it hard to heard distant calls.
  • Do what you can to provoke calling, while being mindful of disturbing their breeding preparations. No more than once per site is required if a reply comes. A lure could be use, but I have only used hooting with cupped hands. It is vital that fingers are slightly wet (small bottle of water needed) otherwise a wuffly sound tends to result; with a good seal you can produce a far-carrying ocarina hoot without too much trouble; per BWP a standard hoot call is this pure hoot, followed by a gap of 2-5 seconds, then the brief "hu" call and the wavering hoot, quite easy to generate with a little practice; however I suspect any approximation to a hoot can be enough to rouse their interest.
  • If you get one hoot don't leave immediately but make sure there are no replies from other birds nearby, you might get two additions or a count increase once they are calling to each other.
  • It takes very little to provoke alarm calls from a Tawny, indeed any loud noise seems to work (witnessed from gun fire/fireworks), perhaps not to be recommended but I do try clapping on occasion; but more relevant in many cases is the sound and lights from a car, anywhere where traffic is not routine, e.g. woodland track - listen immediately on arrival as bird may withdraw from "threat".
  • Seasonal variation - not sure I have detected any of this, under right conditions can be very vocal any time of the year suspect other factors (above) more important.
  • Persistence; we might imagine that with a strongly resident species they like the same patch of wood and stay there; evidence from repeated visits to same sites (5-10 visits for several sites before first found) suggests not, they will roam around at least within an area of a tetrad, thus if you can't hear them at greater range, or prompt them to call, there is no substitute for going back several times
  • Except residents' reports of course, always worth asking as it might be surprising where they are regularly heard, even in unpromising locations.
  • Finally presence can be confirmed by other signs, pellets, feathers, etc. Have so far devoted no effort to locating such as it is probably pretty inefficient on average.

By contrast, final efforts for Barn Owl were unproductive. Scoured the area from Cousland (NT36Z) to East Linton (NT57Y) on the Tuesday evening along corridor S of Tyne, where many remaining gaps in map (above), but neither that trip nor the others produced any - the only exception being one recovered freshly dead on the A1 at St Clement's Wells (below). Other reports suggest there are still good numbers e.g. in parts of the Borders but again the difficulty of finding any in lowland East Lothian reaffirms view of very depressed numbers. It also serves to reemphasise how the main roads can be a blackhole for them - the few that encounter them, often young birds wandering from natal areas, often do not last long.

Other atlassing was mainly towards plugging those remaining annoying gaps in maps of very common species - mopped up Herring Gull for NT68A, Pheasant for NT57Y and Rook for NT47U, also Skylark and Oystercatcher becoming very widespread and surely with extensive coverage in the last week of February the mapped distributions would be very much more complete. After several dedicated trips in search of Grey Partridge in my home tetrad (NT47N), and of course lots of casual observations, had depressingly concluded they had gone since I logged them early on for breeding, but am now informed per landowner/farmer they have been regular this winter around Harelaw/Redhouse. Another message we seem to be getting all the time, the immense value of third party reports from residents, all comes down to time in the field and there's no substitute for living/working there!

The final list of targets found ranks as follows, after Tawny:

  1. Linnet 10
  2. Pied Wagtail 10
  3. Black-headed Gull 10
  4. Jay 9
  5. Treecreeper 9
  6. Feral Pigeon 8
  7. Tree Sparrow 8
  8. Meadow Pipit 7.5
  9. Brambling 7
  10. Bullfinch 7
  11. Goldcrest 7
  12. Long-tailed Tit 7
  13. Magpie 7
  14. Mute Swan 7
  15. Skylark 7

So now rest for one month (needed) before even greater exertions are required to finish up the breeding atlas. Actually, for Tawny Owl which is so resident, there must be a value in combined breeding/winter maps so I will not be going all out to prove presence again in all of same tetrads - breeding will be the main focus.

* Hoodless & Coulson (1998) Breeding biology of the Woodcock Scolopax rusticola in Britain, Bird Study 42, 5, 195-204

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