Tuesday 25 May 2021

Wildlife in full swing

 

Wildlife in full swing


Since we re opened in the middle of April we have had dry and cold weather followed by wet and cold weather, so the arrival of summer migrants has been delayed, a similar story across the UK.

By the beginning of May the first swifts (2nd) and house martins had arrived and now when the weather is cold and wet the number of swifts and hirundines (swallows, sand martins and house martins) number in the hundreds and it is quite a sight as they feed on the emerging flies. The number of feeding birds has attracted several hobbies throughout the month and the resident pair of sparrowhawks frequent the reservoir wall, no doubt in anticipation of an easy meal; the male is regularly seen from reception hide.

The woodland across the reserve has burst into song during the month as more summer migrants have arrived. Early May allows a brief glimpse of the songsters before the trees come into full leaf and the birds are lost in the canopy. Nearly all the regular summer migrants have now arrived; chiff chaff, willow warbler, common whitethroat, sedge warbler, reed warbler, blackcap, garden warbler are all to be found along with the resident Cetti’s warblers. Garden warblers and reed warblers have been the latest to arrive but have given good views to visitors, particularly the garden warblers which have been singing out in the open near the path. Cuckoos have been heard on several occasions in south scrub but it does not appear that any have stayed in the area. The arrival of the summer migrants has added to the woodland chorus which up to April was made up of wren, robin, blackbird, song thrush, bullfinch, treecreeper, dunnock, greenfinch, chaffinch and goldfinch. A pair of great spotted woodpeckers are resident alongside the treecreepers in the reception wood and a pair of tawny owls is also nesting in that part of the woodland and we are anticipating the fledging of youngsters very soon. Both goldcrest and chaffinch have nested very near the car park and are often seen feeding around the wooden office building.


Water violet flowering in reception pond


Semifree morella


Vinegar cup fungus

The woodland floor is covered with more flowers coming into bloom. Wild garlic and dead nettle were the first to appear following the earlier violets and ground ivy but now there are a few bluebells (although the ones on the reserve are not native), pink campion, yellow archangel and woodland forget me not. The blackthorn blossom has died off and in the last week been replaced by hawthorn which is attracting a host of pollinators. Also, in the woodland there have been some fungi. A couple of species of slime fungi at the beginning of the month and more recently vinegar cup fungus and semifree morella. So, as well as searching the canopy to find the singing birds, make sure you look closely on the woodland floor. One of our volunteers happened upon a roe deer fawn when he was doing just that.


Young roe deer fawn

In terms of insects the butterflies, moths, dragonflies and damselflies are also late to appear and are still in low numbers. As regards butterflies, brimstone, speckled wood, small tortoiseshell, small green veined white and orange tip have all been seen. Our volunteers that set out the moth traps have had a very slow month with Least Black Arches, Yellow barred brindle and an English sulphur tubic being the highlights. Four spot chaser dragonfly and two species of damselfly, the common red and the large red are the only ones to have emerged in the last week.

On the water bodies there are still about 20 tufted duck on D reservoir and 4 great crested grebes which have been seen displaying. Elsewhere gadwall, mallard and teal have been breeding. A drake garganey appeared on south marsh on 4th /5th May, then a second male made an appearance on 10th May but these were last seen on 12th May. Greylag geese have young on North and South marsh and two pairs of mute swans have bred, one on north lagoon, one on south marsh west. There are 64 nesting pairs of black headed gull and possibly two pairs of common tern nesting on south marsh. Yellow wagtails have dispersed onto nearby farmland to breed, numbers dropping to single figures in the past couple of weeks compared to over 40 at the beginning of May. Pied wagtails and the occasional grey wagtail can be spotted feeding on the flies on top of the reservoir walls.


Oystercatcher chick (photo Maurice Dowson)


Greylag family on south marsh


Male garganey (photo Maurice Dowson)

There have been several waders passing through, usually on south marsh with a greenshank, 2 dunlin, 4 ruff and 2 common sandpipers on the 5th, common sandpiper on 11th and a wood sandpiper on 21st. A pair of oystercatchers have raised 2 young on south marsh and a pair of little ringed plovers continue to try to nest, let’s hope they are successful. Lapwings have been seen displaying over decoy fields and at Watton nature reserve.

There appears to be two pairs of marsh harrier breeding, one near North marsh, one near south lagoon and a pair of kingfishers in the southern part of the reserve. Both species attracting interest as they are such iconic species of a wetland habitat. Little egrets are seen now singularly passing through, but the grey heron colony is very busy in the north marsh area of the woodland. Osprey is another species that we would like to stay in the area, and one has been seen on several occasions, probably a non breeding bird and still a nice record for the reserve.


Common tern (photo Maurice Dowson)

And finally, the marsh frogs are in full voice and can be found in any of the lagoons and ponds, that distinctive “song” of croaks and quacks puzzling many a new visitor. They provide an excellent food source for many of our predators but it is the grass snake that has not been seen too many times just yet, no doubt it, like the rest of the wildlife and ourselves is hoping for warmer weather.

Monday 10 May 2021

Monitoring our wildlife

 Bird ringing at Tophill Low

Last week saw the start of our bird ringing season here at the reserve. For the past eleven years Graham Scott has conducted a Constant Effort Site (CES) ringing scheme in an area of South Scrub. 


Cetti's warbler

The CES scheme, co-ordinated by the British Trust for Ornithology starts on the 1st May each year and runs till the end of August. During this time ringing days are planned (weather permitting) every 10 days which equates to about 12 sessions. Here at Tophill, Graham has carried out this commitment each year with a team of ringers (except in 2020) and in doing so has ringed 1,673 birds, covering 35 species, ranging from kingfishers to Cetti’s warblers.


Sedge warbler

The CES scheme has been running since 1983. Ringers use the same nets in the same locations over the same time period at regular intervals throughout the breeding season and this is carried out at 140 locations across the UK. The aim of the scheme is to monitor a particular site to establish the number and variety of species that are breeding in the area. It provides valuable trend information on abundance of adults and juvenile productivity at a particular site and also adult survival rates for 24 common songbird species. Re traps give evidence that birds are staying within the targeted area year on year and the number of each species ringed gives an overall picture of whether the numbers of certain species are remaining constant or changing over the years. Re traps of adults ringed in previous years are used to estimate survival rates. All this data adds into other data sources such as the Breeding Bird Survey and other ringing schemes co-ordinated by the BTO providing a detailed picture of bird populations.


A tiny metal ring is placed around one leg


Birds are caught in mist nets and carefully removed by trained ringers who must hold a licence

The process of bird ringing is carried out by people who have been trained and hold a valid permit that is issued by the BTO. Birds can be caught by a variety of methods but the most common, and the one used at the reserve is by mist netting. This requires a very fine net, secured by poles that is placed within a certain area. Birds are unable to see the net, they then fly into it and are safely held in a pocket of netting before being carefully removed ready for processing. The process consists of identifying the species, noting its sex and age, recording its wing length and its weight. A tiny metal ring is then carefully secured around a leg, the specific number recorded before the bird is released. The metal ring is similar in weight proportionately to wearing a wristwatch, causing no adverse affect to the individual


The wing length is recorded


The bird is weighed

Last Monday a total of 46 birds, of 17 species were caught and ringed, 7 birds were re trapped birds; a good start to the survey this year. Of the birds that had been re trapped; a reed warbler was first ringed in Jun 2019, a willow warbler was ringed in August 2020, a robin was first ringed in April 2019, a Cetti’s warbler had been ringed in June 2019 and a very long lived long tailed tit was ringed as an adult bird at the reserve in June 2018. Small passerines such as these species are known to be fairly short lived, information such as this data adds to that evidence.



Long tailed tit

Today the ringing team were back, they caught less birds, only 20 this morning as the weather wasn’t as ideal and will return on another ten occasions throughout the breeding season.



Dunnock

Over the years (2010-2019) the scheme on the site has shown that willow warbler and chiff chaff numbers have remained fairly constant, with two poor years (2014, 2015). Sedge warblers have increased throughout the period but have shown high fluctuations in numbers between years. Similarly reed warbler numbers have increased. With both species this may be due to the addition of a new net ride near some reeds but within the period that this ride existed numbers have also increased. The fluctuation in numbers in recent years is often due to ringing on days when passage birds appear to be moving through. Blackcap  numbers have remained fairly constant with double figures ringed annually in most years.

Some notable recoveries (when the bird has been caught in a different area to the CES site) have been a sedge warbler  that was caught in Lesteven, France, a reed warbler than was caught in Jersey, another two reed warblers were re trapped in Sussesx. A blackcap has been recovered at Stanford reservoir in Northamptonshire, a robin at Spurn and a long tailed tit travelling to Flamborough head, East Yorkshire. Two birds that were caught at Tophill, yet ringed elsewhere are both reed warblers, one ringed in Woumen, Belgium and one ringed at Fishlake meadows in Hampshire.

The scheme will be up and running throughout the summer now that rules have been relaxed and the ringing team are able to get back on site. We will continue to keep everyone updated on this fascinating aspect to our wildlife monitoring at the reserve. Our thanks go to Graham Scott and his ringing team for their efforts, in particular Will Scott who has provided all the ringing data records.