BSNHS

©BSNHS 2014

Visit Dates

22nd March

6th, 20th, 30th April.

15th, 24th May.

6th,26th June.

25th July.

Results

The results are presented in a spreadsheet as an Excel document, together with individual species maps in pdf format for those species where the location of the nest can be estimated with reasonable certainty.   Maps have not been produced for those species where the location of nests is uncertain since this would result in false or spurious data, particularly where the species in question probably bred outside the lake survey area.

Comments

As in the previous year, predation and/or disturbance were major factors this year in determining the numbers of surviving young.   On some visits, absolutely nothing was observed on the Decoy Lake, presumably on account of earlier disturbance by dog-walkers, whose numbers have increased dramatically in recent years.

While one to three Great Crested Grebes were present at times on the main lake during the breeding season, no young have been seen and it is uncertain whether they bred this year.

A pair of Mute Swans again made an attempt to breed at the far end of the Decoy Lake but this nest appeared to have been abandoned by 24th May and on subsequent occasions the birds were seen mostly on the main lake.

Canada Geese were observed nesting on a tree stump in the main lake, but no young were seen.   Greylag Geese numbers peaked at 23 birds on 24th May, but no definite breeding was confirmed in the Lake area.   At least five Mallard nests were successful, with broods totalling 31 young.   Although Snipe were observed on 6th and on 20th April, they were not seen subsequently so it must be assumed that these were wintering or passage birds.   A Water Rail was seen on 30th April but these elusive birds are notoriously difficult to observe and it is not known if breeding occurred this year in the marsh area.

Both Coots and Moorhens were observed on nests and juveniles of both species were observed although the numbers of both were very low towards the end of the survey, suggesting losses through predation.

 The Common Terns have been successful again this year.   Having initially started to nest on the old tern raft, a bird was observed sitting on the nest on the new tern raft on 26th June and a single juvenile was being fed on 25th July with both adults present.   Also, Pied Wagtails appear to have bred on the old tern raft since two birds were observed there on several occasions with one bird seen disappearing into the vegetation whilst the other kept watch.

The status of the Swallow was initially unclear, with birds observed prospecting for nest sites in the fishermen's shelter early in the season, but not later on.    However, on the final visit on 25th July, two Swallows were present in the fishermen's shelter with one attending the nest while the other was perched nearby.   Reed Buntings were observed carrying food so are presumed to have bred and Reed Warblers are also assumed to have bred in the reedbed at the marsh end of the lake, since territorial behaviour was observed on various occasions.   Juvenile Dunnocks were observed in the area south of London Bridge and a Robin was observed on several occasions disappearing up the chimney from the right hand fireplace in the fishermen's shelter.    Blue Tits were observed carrying food into one of the nest boxes on the exterior wall of the shelter.   Although present during the early spring months, Willow Warblers were not heard after 15th May and no evidence of breeding has been found, so it must be assumed that the observed birds moved on as the season progressed.

Accurate counting of Jackdaws again presented a bit of a problem this year since their prime nesting tree lost a significant part of its superstructure during the 2013/2014 winter gales, including many of the hollow branches.   As a result there appears to have been some intense competition for nesting sites within the other unaffected trees, possibly to the detriment of Stock Doves where fewer were observed than in previous years.   However, Jackdaws may have bred inside the southernmost chimney of the building behind the Shell House, where they were seen on various occasions.

Chris Swan

7th August 2015.

Big Forest Bird Watch - 2015