Tuesday, 29 July 2014

Noar Hill, Revisited - July 2014

Around this time last year I visited the Hampshire and Isle of Wight Wildlife Trusts Noar Hill Nature Reserve in order to carry out a grasshopper survey. The visit was a success as we recorded the local Rufous Grasshopper, along with a variety of other species. The Trust is looking to set up a standardised monitoring programme for the species, so when I was asked to assist I jumped at the chance. We visited the site on 22nd July with the main purpose to survey for grasshoppers, and test the survey methodology that had been designed, but whilst I was there I took the opportunity to catch up with a few other species. 

As I have covered grasshoppers before I didn't take any photos, but during the survey we recorded Rufous, Common Green, Field, Stripe-winged and Meadow Grasshopper and Speckled, Dark and Roesel's Bush Crickets. Noar Hill is well know for its orchids too and there was plenty of evidence of them, but the only species in flower was the Pyramidal Orchid

Pyramidal Orchid Anacamptis pyramidalis

As would be expected at this time of year, butterflies were everywhere and making use of the abundance of nectar available. Meadow Brown, Ringlet, Gatekeeper and Red Admiral were the most numerous, the latter species making the most of the flowering Hemp Agrimony.

Red Admiral Vanessa atalanta

Silver-washed Fritillary and Marbled White seemed to be just hanging on, with some very tatty individuals present, whereas the Brimstone's and Green-veined White's were immaculate and clearly evidence of a recent emergence.

Brimstone Gonepteryx rhamni
Green-veined White Pieris napi

We also recorded Large and Small Skippers, but the only species of Blue recorded was Common Blue. This time last year their had been an abundance of Chalkhill Blues at the site, but we may have been a bit early this year.

Small Skipper Thymelicus sylvestris infected with the red mite Trombidium breei

Whilst photographing a Small Skipper and Common Blue I noticed that they were infected with a small red mite. I did a bit of research and it appears that this mite is Trombidium breei, which usually attaches itself to the legs or thorax of its host. Apparently there are no detectable negative impacts on the host butterfly, and the mites transfer from host to host via flower heads. For more information on butterfly parasites check out the following link enemies of butterflies.

Common Blue infected with Trombidium breei
Female Common Blue

Another species recorded was the Small Heath, but only in small numbers. In total we recorded 13 species of butterfly during our visit.

Small Heath Coenonympha pamphilus

Despite the orchids not being in flower there were plenty of other plant species on show, including bellflower, yellow-wort, Greater Knapweed and Harebell.

Greater Knapweed Centaurea scabiosa
Harebell Campanula rotundifolia

The Small Scabious flowers were proving very popular with the Six-spot Burnet moths, which were the most numerous moth species we recorded.

Six-spotted Burnet Zygaena filipendulae stephensi on Small Scabious

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.

Monday, 14 July 2014

Aromia moschata on the River Itchen, Shawford, Hampshire - July 2014

Yesterday (13th July) afternoon I went for a stroll along part of the River Itchen near Shawford, Hampshire. The River Itchen is one of the best examples of a chalk river and flows for 28 miles from mid-Hampshire to Southampton. The Itchen Navigation is a modified part of the river and former canal which was used to ship freight, such as timer and chalk, to the Port of Southampton. The advent of the railway saw the end of the need for the navigation and it fell into disrepair. The Hampshire and Isle of Wight Wildlife Trust managed a project to restore the old navigation, and preserve it for future generations. Details of the project can be found here

I was keen to see the Itchen Navigation, which was my main reason for going there, but as with any site, you never know what wildlife you might find. Being a Sunday morning it was quite busy, with dog walkers, fisherman, picnickers and swimmers all using the river. But at the busiest spot, and where one might least expect to find something, I noticed a large longhorn beetle quietly going about its business.

The Musk Beetle Aromia moschata

The Musk Beetle Aromia moschata is a large metallic green beetle, with a body length of between 13 - 35 mm. It is easily identified by its large size and metallic green colour. Adult beetles are found in wet areas from May to September, and can be found visiting the flowers of umbellifers, such as hog weed and meadowsweet, as with this individual. 

Musk Beetle

The larvae live in young and healthy willows Salix sp. and take three or more years to reach maturity. The antennae are conspicuously long, and in the male reach the apex of the elytra, when laid back. Looking at the length of the antennae on this individual it is clear that it is a male.

Musk Beetle

In the UK the Musk Beetle is locally distributed and is classified a Nationally Scarce B, which means that the species is found in between 31 out of 100 tetrads. Referring to the National Biodiversity Network Gateway, which is found here, I see that the species has been recorded in this 10km square before, albeit to the south.

Sunday, 13 July 2014

Prehistoric Woodpecker - July 2014

The local Green Woodpeckers were particularly vocal this afternoon in the field behind my house, but even so it was a real surprise when one turned up in my net. This is not a species I get to handle that often, although we did catch three during the ringing sessions at Titchfield Haven last year. This individual was a juvenile bird that was still exhibiting the heavy mottling that they show, and the grey iris. In this plumage you have to admit that Green Woodpeckers look as if they would be better placed in prehistoric times, and resemble a Pterodactyl.

Juvenile Male Green Woodpecker

Juvenile Green Woodpeckers undergo a partial post-juvenile moult which involves the primary, tail and body feathers; they do not moult their secondaries, primary coverts or tertials. Adult birds undergo a complete moult post breeding. They can usually be sexed from June, and it is possible to see the red malar stripe in the picture above that identifies this bird as a male.

Juvenile Green Woodpecker showing primary moult

The image above shows the primary moult in this individual, and no moult in the secondaries or tertials, as would be expected. Green Woodpeckers will breed at one year old and according to the BTO website the longevity record is 15 years and 8 days and was set in 1985.

Juvenile Green Woodpecker showing bright yellow rump.

Green Woodpeckers feed mainly on ants, which is why they are often seen on the ground. Their long thin tongue is around 10cm long and is armed with barbs that hook the ants out of their nests. Local names for the Green Woodpecker include 'yaffle', 'pick-a-tree' and 'rain fowl'.

Some clues to ageing birds - July 2014

Normally by now we would have started ringing at Titchfield Haven, but unfortunately we are running very behind this year. In preparation for a start next week, we did cut in most of the net rides this morning, and hope to finish things off one evening during the week. With no ringing at the Haven my activity has been limited to occasional sessions in the garden and so for this post I thought I would go through some of the ageing features on the species that I have caught.

Over the last 3 or 4 years I have regularly caught Great-spotted Woodpeckers, particularly through June, July and August, when the young have recently fledged. Determining the age of a juvenile Great-spotted Woodpecker is pretty straight forward since they have red crown feathers (see below). Birds cannot be sexed until they have undergone their post-juvenile moult and the red nape patch has developed in males, or not in the case of females.

Juvenile Great-spotted Woodpecker

Juvenile birds undergo a partial post-juvenile moult that includes body, primary, upper wing coverts and tail feathers. Usually most, if not all, of the secondary, tertial and greater coverts and primary coverts are retained. Following completion of the post-juvenile moult it should be possible to see a contrast between retained juvenile feathers and new black adult type feathers. Juvenile birds also show white tips to the primaries, that is until they have undergone their post juvenile moult and replaced their primaries.

Active wing moult of Great-spotted Woodpecker - note the white tips to the outer primaries of the juvenile feathers which will not be present in a juvenile bird.

Blackcaps breed in the scrub behind my garden and so I often catch newly fledged birds when ringing in June and July. Juvenile birds have a dark brown cap, which to the unwary could be confused with the chestnut brown cap of a female bird. They cannot be sexed until they have undergone their post juvenile moult. Juvenile Blackcaps undergo a partial post juvenile moult (which does not include primary, secondary or tail feathers), whereas adults undergo a complete moult post breeding, replacing all their feathers. It may therefore be possible to see a contrast in retained greater coverts in juveniles to aid ageing.

Juvenile Blackcap - showing brown crown, note the deeper brown colour as opposed the the chestnut of a female.

The shape and extent of wear on feathers can be very useful when ageing birds in the autumn, particularly tips of primaries and tail feathers. Juvenile tail feathers are generally pointed and thinner, but also look at the ground colour of the feathers. Juvenile feathers tend to have a brownish wash unlike the greyish tone of adult feathers, although this can be more difficult to determine in female birds.

Blackcap - Juvenile tail; pointed tail feathers are often a good clue to the age of a bird

Blue Tits and Great Tits follow the same moult strategy as many passerine species, with adults undergoing a couple moult of all feathers post breeding where as juveniles undergo a partial moult. This post-juvenile moult does not include any wing or tail feathers and therefore any bird that is replacing it's primaries (as in the image below) must be an adult. In the image below it is possible to see a contrast between the new blue adult primary coverts and the old greenish juvenile ones, thereby making this bird as an age code 5.

Post Breeding Wing Moult in a Blue Tit

The image below illustrates the post-juvenile moult of a Great Tit. Although it cannot be seen in this image, there is no moult in the primaries or secondaries, but there is in the greater coverts. It is possible to see the old juvenile retained greater covert (and all primary coverts), contrasting with the new adult type feather, which is still growing and partially in pin.

Post Juvenile Wing Moult - note contrast between new adult type feather and retained juvenile one.

Another feature that can indicate the age of a bird is a fault bar or growth bar on the tail feathers. Such features are caused by structural differences that have occurred during the development of the feather. If, as in the image below, the pattern forms a band across the tail at the same location on the feather, this indicates that all the feathers have been grown at the same time, as when in the nest. With the exception of the few species that periodically moult their tail feathers, or where an individual has accidentally lost its tail, this can point to the bird being a juvenile. When an adult bird replaces its tail feathers, as with a post breeding moult, the bird would replace its feathers in pairs, and therefore any anomaly would not appear as a band across the tail.

Fault Bar on a Great Tit

It is important to remember when ageing birds to look at a number of features in combination before reaching your conclusion. Even if you have a bird of known age it helps keep you eye in for when you are faced with a difficult individual.

Sunday, 6 July 2014

Patch Birding at Curbridge - July 2014

After my visit to the Black Redstarts I stopped off at Curbridge for a spot of patch birding. By early July there can often be small numbers of waders present, which are probably failed or non-breeders. The tide was out, but coming in and so I walked along the creek from the Horse and Jockey end. There were a few Black-headed Gulls, four Little Egrets, Common Moorhen, Mute Swan and several Mallards, including one duck with about 10 recently hatched chicks. As I approached the main estuary I spotted a couple of Common Greenshanks and two distant Eurasian Curlews.

The greenshanks were both adult birds, which would be expected this time of year. They are very obvious to tell from juveniles by the heavily streaked and spotted upper breast and their broad and more rounded scapulars. The two birds were roosting on the waters edge directly at the mouth of the creek and therefore I was able to creep up and get some great views.

Adult Common Greenshank - Curbridge
Adult Common Greenshank - Curbridge
Adult Common Greenshank - Curbridge

After I had finished watching the greenshanks I turned my attention to the rest of the estuary. There were a further six Little Egrets, around 70 Black-headed Gulls and two Eurasian Curlew. Scanning over the mud I picked up two adult Oystercatchers and a chick. Interestingly the chick was still flightless and given that it was on a piece of mud that is totally covered at high tide, it will be interesting to see where it goes. 

Oystercatcher with chick - Curbridge

At the far end of the estuary I suddenly noticed a tern feeding over the water. It is not that uncommon to see Common Terns this far up the River Hamble, but this bird was an adult Sandwich Tern, which I must admit I don't recall having seen before. It didn't come very close but I still managed to grab a record shot before it turned around and headed back down the river. 

Adult Sandwich Tern - Curbridge

The only other bird of note was a roosting Lesser Black-backed Gull, so with time pressing on I headed back to the car. On the way back my attention was drawn to a large orange butterfly which turned out to be a Silver-washed Fritillary, my first of the year. Unfortunately I only had my long telephoto with me and was unable to get a photo.

Saturday, 5 July 2014

Breeding Black Redstarts - July 2014

In Hampshire the Black Redstart Phoenicurus ochruros is considered to be a scarce passage migrant and winter visitor that occasionally breeds, and when it does breed there are usually only low numbers (one or two) of breeding pairs. The UK breeding population according to the BTO 2007 - 2011 Bird Atlas, is currently agreed at between 19 - 44 pairs. It is evident from this information that Black Redstart is a pretty rare breeding bird in Hampshire, so when I was informed of a pair on a private site near Lee-on-Solent, I was keen to check them out to see if the chicks could be ringed in the nest. 

Access to the site was tricky and needed security clearance and I needed to arrange for a Schedule 1 endorsement on my ringing permit, since the species is afforded extra protection whilst breeding. With help from the Dean Swennson who found the birds and the BTO for immediately issuing me with the appropriate endorsement, we were ready to go.

Black Redstart - with Prey

We arrived on site and were immediately watching the two birds going to and from the nest site feeding their young. We watched them for a while and were impressed at how quickly the were able to find prey and return to the nest, it was just continuous. The birds are pretty accustomed to people, since there are plenty around on weekdays, and so seemed unfazed by our presence.

Black Redstart - the darker bird

It was raining occasionally first thing and a bit chilly, so rather than disturb the nest we sat and watched the birds. Normally I would have considered sexing them to be quite easy, but both birds feathers were very worn, and neither bird was showing any evidence of white wing flashes. One bird was darker but it didn't look right for a male.

Black Redstart territory

The territory was located amongst some fairly run down but still used industrial buildings that were constructed of a mix of corrugated asbestos sheeting and block. Opposite these buildings there was a small area of grass and a single oak tree, and this was where the birds were mainly feeding. The grassland was enclosed within a Heras type fence and both birds were regularly using this to spy their prey.

The nest as it turned out was inaccessible. It was located in a live electrical switching unit (see below) which was locked, but partially rusted out. The birds were entering it from the underside where it was badly rusted, but I could not see the nest. It was a real disappointment but there was no way I was going to blindly put my hand into a buzzing box that was connected to mains electricity.

Black Redstart nest location

I had prepared myself well though in case of disappointment and had packed a couple of spring traps and some meal worms. It was obvious where the birds were mainly hunting, so I set the two traps on the ground by the Heras fencing......and almost immediately caught a bird.

Second year presumed male

This was not the bird that I had photographed above, but the other one of the pair and its plumage was in terrible condition. Black Redstarts undergo a complete moult post breeding, with juveniles undergoing a partial post juvenile moult. It was clearly evident, based on the contrast between the brown post juvenile feathers and the blacker adult type, that this bird was a second year bird.

Second year Black Redstart

As if the contrast in the feathers wasn't confirmation enough of age, the wing and tail feathers were also extremely abraded. The tips of the primaries were particularly bleached and worn.

Extremely abraded with feathers

With regards to the tail, all of the feathers were worn but the central pair of feathers were again extremely worn. 

Abraded tail feathers

I presumed that sexing the birds would be easier in the hand since the female should show a well developed brood patch. We didn't catch both of the birds, but this bird showed no evidence of a brood patch and therefore I presumed that it was the male.

Ringed Black Redstart with beak full of prey

After release the bird was straight back into feeding its young, but now seemed slightly more wary of our presence so we sat back and watched from a distance. According to the BTO ringing totals only 43 Black Redstarts have ever been ringed in Hampshire, it would be interesting to know how many of those were pulli. Given that we are now at the beginning of July and the condition of the birds feathers, I wonder if this was their second brood.
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