Wildlife and Conservation Review of 1999
41
shoots and leaves. This unsettled weather was also a feature of Mediterranean areas, and delayed the
arrival of the bulk of the summer migrant birds, although a Red-rumped Swallow made it to The
Naze by the end of the month. At least four Cetti's Warblers were located in south Essex, while a
Marsh Warbler was apparently holding territory in a coastal location. Stonechats on breeding
territory showed a welcome increase over recent years, with 6 pairs at East Tilbury and 15 at Rainham
contributing to a south Essex total of 25, and a Canvasback stayed at Abberton for a couple of
weeks, presumed to be the returning British first from 1998.
April closed with a stormy, wet spell which raised rainfall levels to well above average, and set the
scene for an unsettled May. Daytime temperatures were above average, but nights were noticeably
cool (depressing moth trap catches), and it was again rather wet. This further delayed breeding of
some summer birds, such as Swifts, which had already been held up by weather conditions elsewhere.
Earlier nesters seemed to be having a successful breeding season, although over a more protracted
period than usual; perhaps 1999 would see a recovery from past breeding failures? Among the more
unusual breeding records, Grey Wagtails nested on Colchester East Mill, some 6 pairs of Sandwich
Tern settled in with the Black-headed Gulls at Hamford Water, and good numbers of Little Terns
were investigating the various beach recharge areas. Most notably, about 15 pairs adopted the new
beach at Jaywick, apparently oblivious to the presence of thousands of people and dogs. Even more
exciting though was the discovery of at least one and possibly up to three pairs of Marsh Harrier
establishing territories around Hamford Water.
During May, and into June, RSPB staff from Old Hall Marshes (Chris Tyas and Paul Charlton)
undertook a comparative survey of the breeding waders on their reserve with those on Horsey
Island, a private island within the Walton Backwaters. Old Hall is 'known' to have densities
comparable with or higher than any other site in the county - until they found that the density on
Horsey Island was some seven times greater. This is presumably unique in Essex; the best area
supported up to 3.5 pairs per hectare (not unfavourably comparable with the best UK habitat for
breeding waders, Scottish machair, typically with 7.5 prs/ha). A remarkable total of 215 pairs of
Oystercatcher were recorded, especially remarkable given that Breeding Birds of Essex suggests
a county total of only around 300 pairs: this survey must raise that estimate to more 1 ike 450 pairs.
And it was not just waders - various breeding wildfowl were noted, including 40 pairs of Shelduck
and too many feral geese, along with an unprecedented open grazing marsh nesting colony of Black-
headed Gulls. Tour factors were identified as contributing to this amazing site: a zero-tolerance
policy of ground predators and crows; minimal human disturbance; a successful water management
regime, retaining high water levels; and the presence of sheep grazing during the breeding season
(although the latter is believed to reduce its attractiveness for various duck species).
Meanwhile, Andy Schofield of the RSPB Stour Estuary reserve was undertaking a pilot survey of
some borrowdykes of north Essex and south Suffolk. His Common Bird Census revealed more
than twenty breeding species, including several species of concern including Corn and Reed Buntings
(16 and 34 pairs respectively in 10km around Hamford Water), Yellowhammer (14 pairs) and
Skylark (39 pairs). In addition, there were 39 pairs of Mallard and 18 of Tufted Duck. Most
numerous were 116 pairs of Reed Warbler and 63 of Sedge Warbler: if these figures are
representative, it is predicted that the Essex borrowdyke system may support 2784 and 1512 pairs of
the latter two species in total. He also recorded significant numbers of Adder and Common Lizard,
several Hairy Dragonflies, two possible Scarce Emerald Damselflies and three pairs of Water Rail.
Peregrines did not repeat their breeding attempts of 1998 in Dockland, but there were four pairs of
Black Redstart, and the Beckton gull colony increased to 53 pairs of Lesser Black-backed and 23
Essex Naturalist (New Series) 17 (2000)