Monday, 1 March 2010

Wknd 27-28 February

Final wknd of the month coincided with the end of winter atlas (year 3 out of 4) so most effort again on chasing missing species, despite continuing atrocious weather. Around areas east of Tranent on Saturday, several ticks now bring up all NT47 tetrads to at least 37 species, though all with one or two remaining obvious omissions, still including Wren at New Winton where failed again. Despite some snow cover, good numbers of Fieldfare in crop, with c. 600 in flocks (190+160 Liberty Hall, 120+20 Jersulem Fm, 80 Redcoll, etc).

Sunday saw the highest tide I have ever witnessed along Seton coast, with Seton harbour wall fully engulfed and waves crashing over promenade path onto grass, normally the domain of dog walkers. Lots of wood in the sea, and gulls feeding on storm debris along upper shore, first LBB back to join overwintering Lucy who was still at the harbour. Nice to record a Stonechat again by the Seton Burn. Offshore, Gannets ticked in several tetrads and plenty Fulmars sheering on the strong wind.

Finally, got the latest batch of owl post mortems back, 5 out of the 7 collected mid-Jan to mid-Feb, all of which would have perished during pretty severe conditions weather-wise, with snow lying for a long period prior to most being found - so had wondered if they would have been in poor condition. Quite the contrary, all 5 were adults (3 female/2 male), all with a top body condition score (for fat and muscle bulk) of 5/5, all a decent weight (minimum 317g) and moreover, all 5 had well-filled intestines and most had been feeding well, e.g. gizzards of the two collected on 15/1 contained 4 short-tailed field voles (Dolphingstone A1) and 2 small rodents (Newton A720), respectively.

It fairly straightforward to determine sex in all these cases, the illustrated male from Newton A720 being very pale above, and completely spotless below, equally with the Sheriffhall A720 male (recovered in crouching position), as shown in two more pics below:

This specimen was pristine with no external signs of injury, but cause of death was a ruptured atrium and liver, so it had clearly been struck, but perhaps not died immediately.

The females are distinguishable in more distinct and darker upperpart markings (i.e. bars on flight feathers, plus grey on mantle and hindneck), obvious spots below, and the buffish colour on the sides of the neck, all shown well in further pics below of Whitecraig A1 bird:

Pics in the earlier post clearly show dark grey on mantle and hindneck, and buff neck sides, though spots are relatively small. The final two pictures show the Mungoswells B1377 female, which had more distinct and larger spots spread right across underparts:

Based on these features, it should be possible to sex many owls in the field/from photos, though BTO guidance (leaflet 23) suggests that only about half are easy and 10% can't be sexed in the hand, so some caution is still needed with any intermediate birds.

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