Sunday, 20 July 2014

The First Common Cuckoo ever ringed at Titchfield Haven - July 2014

The title pretty much gives away what the highlight of our first bird ringing session of the autumn at the Haven was today, and so I'll start this blog with a picture of it, a juvenile Common Cuckoo. It was a welcome reward for our hard work cutting in the net rides over the last week and the first Common Cuckoo ever ringed at the Haven.

Juvenile Common Cuckoo

The morning began with a 4am start and as usual our nets were set low in the hope of catching Grasshopper Warblers. Our quest started well and we started the season with nine new Grasshopper Warblers, all of them juveniles.

Juvenile Grasshopper Warbler (yellow form)

We caught most (six) of the Grasshopper Warblers in the first round, but added the odd single throughout the morning. The rounded tail shape is typical of the genus Locustella but the dark streaks along the shaft of the under tail coverts can be very variable in their extent.

Under-tail Coverts and Tail of Grasshopper Warbler

It was whilst extracting one of the Grasshopper Warblers that we heard an odd call. We recognised it as a juvenile begging call, but couldn't work out what it was, that is until we saw a Cuckoo fly over the top of the reeds. The very next round the bird, or another, was in the net. The bird was clearly still dependant on its unfortunate parents, who happened to be a pair of Reed Warblers, as its wing feathers had not fully grown. According to the BTO website the average wing length is 219mm, this birds wing was only 137mm. This was the first cuckoo I have ever had the pleasure to handle, other than a dead Yellow-billed Cuckoo that was found in Woolston, nr Southampton, many years ago. It was a truly stunning bird with heavily chestnut barred upper parts and strongly barred underparts. Most of the upper parts were pale fringed and the white nape patch, typical of a juvenile bird was clearly visible. The gape was a deep orange colouration, and was striking. After release the bird moved around the ringing area begging constantly, its busy parents in constant attendance.

Juvenile Common Cuckoo
Juvenile Common Cuckoo
Juvenile Common Cuckoo
Juvenile Common Cuckoo
Juvenile Common Cuckoo

A Common Kingfisher would have normally been a good candidate for bird of the session, but on this occasion the juvenile had to make do with the runners up spot. This bird was clearly a juvenile as the front of its tarsus and upper foot was brown and there were dark smudges on the breast, that almost formed a band. In colouration this individual was quite dull, the we considered that the crown feathers were more green-blue, than blue-green, making it a female, but this was the first of the year so we didn't sex it.

Juvenile Kingfisher
Juvenile Kingfisher

A juvenile Reed Bunting was another good bird for us at this location. This individual was sexed as a female due to the pattern and lack of black in the crown and throat feathers. Other species captured included Reed, Sedge and Cetti's Warbler, Blackcap and Whitethroat, Chiffchaff and Goldcrest.

Juvenile Reed Bunting (female)

A canary yellow Willow Warbler was the first of the autumn, and hopefully will be the first of many. They certainly appear to have had a good breeding season at Botley Wood.

Juvenile Willow Warbler

We have often had discussions about ageing Cetti's Warblers. Swensson suggests that there are no plumage differences between adult and juveniles, but adults undergo a complete moult post breeding, whereas juveniles undergo a partial mount. In most passerines this would mean that juvenile greater coverts are retained and thus a difference should be visible. A couple of years ago I read a paper that suggested this was indeed the case and we started looking and ageing birds based on this feature. Given the generally plain plumage, good light is needed to see the feature, but it is visible in some individuals. Today we ringed five Cetti's Warblers, one of which was undergoing its post juvenile moult and had retained two of its greater coverts. It will be interesting to see whether this feather is picked up throughout the autumn as we re-trap this bird, which we will undoubtedly do.

Cetti's Warbler Wing

The session finished with 74 birds ringed of 15 species; Reed Warbler (21), Grasshopper Warbler (9), Sedge Warbler (9), Chiffchaff (9), Blackcap (6), Cetti's Warbler (5), Wren (4), Whitethroat (3), Robin (2) and single Cuckoo, Kingfisher, Blue Tit, Willow Warbler, Goldcrest and Reed Bunting. Let's hope it's not all downhill from here.

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