Friday, 7 April 2017

Spring has arrived on Bardsey, and in some style! Our most sizeable arrival of the year to date arrived today, with excellent numbers of many species, several firsts for the season and fantastic diversity.

Willow Warblers adorned almost every tree and bush. 50 were ringed in the Observatory garden, 12 more at Ty Nesaf, and with field observations a total of 120 were detected today. Chiffchaffs were in fine numbers too, 81 being the second highest count of the season. 25 Goldcrests were mostly in Nant Plantation, 16 Blackcaps included ten ringed in the observatory garden. Warbler wise though, the stars of the show were three Grasshopper Warblers, also our first of the year, with one seen in Cristin Withy and two reeling on the mountainside just above the Observatory.

The identification of Chiffchaff and Willow Warbler can appear complex at first glance, but it's just about knowing where to look.

figure 1

Figure 1 shows both a Chiffchaff (left) and a Willow Warbler (right). Instantly visible is the size difference, with Willow Warbler looking far larger and shows a longer primary projection (highlighted in image). Chiffchaff is often less colourful as well, with the breast a more subdued yellow or even buff and its mantle and wings usually a olive-green colour.

figure 2

When looking at the wing of the bird, the primaries in particular, the difference becomes definitively clear. The primary feathers, the largest of the flight feathers, are numbered from the outside of the wing towards the body. On each primary from P2-5 there are notches on the edge of the feather called emarginations. In Willow Warbler only P2-5 are emarginated, whereas P2-6 are emarginated in Chiffchaffs. This is shown in figure 2 which makes the bird on the left a Willow Warbler and the bird on the right a Chiffchaff.

figure 3

Since both juvenile and adult Willow Warblers do a complete winter moult ageing them in Spring is impossible. However, due to the less durable quality of juvenile feathers compared to adults, ageing Chiffchaffs is a possibility. As is visible in figure 3, the edges to the primaries are very worn and even show some bleaching at the tips, which make this last years juvenile and therefore a 2nd calendar year bird (euring age code 5). In general the feathers of an adult bird would also be more glossy and slightly darker, their primary coverts broad and neatly edged greenish, and finally have darker tail feathers.

An excellent back-up cast of passerines were noted across the island. A stunning male Ring Ouzel briefly showed up in Cristin Withy, with singles of Redwing and Fieldfare at Nant. While common across most of the country, the most notable bird was undoubtedly a Yellowhammer that flew North along the mountain, before briefly settling in Ty Capel. The past five years to 2012 have averaged just two records a year for this island scarcity.  Modest finch passage continued from yesterday, with 22 Goldfinches, 7 Lesser Redpolls (including three ringed and one control) and five Siskins moving through, while the total number of Linnets was down slightly to 187. 54 Swallows, 17 Sand Martins and 18 alba Wagtails moved north, with six White Wagtails on Solfach. Two Tree Pipits (yet another first for the year) included one seen well in Ty Pellaf Withy. 24 Wheatears were scattered across the island, while perhaps the single Starling wasn't quite as exciting as the highlights above, but nontheless a definite migrant!

Lets also not forget, amidst all this excitement, a gorgeous, second-year female Sparrowhawk that ended up in the nets at the Observatory, nor two Buzzards that circled overhead as we took photographs of it. The sea was understandably underwatched, a winter plumaged Red-throated Diver off the North End the only notable sighting, while four Manx Shearwaters called from their burrows in the daytime, with many more come nightfall.

Seven Peacock were also on the wing, alongside a Green-veined White and a Small Tortoiseshell, with three Harbour Porpoise off the West Coast.

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