Titterel time

A long look around Old Hall Marshes shows this reserve to be in good shape. Old Hall retains extensive areas of old coastal grazing marsh by the Blackwater Estuary. Grazing of these ancient marshes, since their enclosure in the Middle Ages, has created a characteristic undulating landscape, with the channels of the old saltmarsh creeks still evident. The ant hills of the Yellow Meadow Ant, estimated to number in excess of 500,000, give credence to the antiquity and uniqueness of this landscape.

The variable topography of the grazing marsh, combined with a carefully manipulated water table and grazing regime, creates a fleet-type habitat ideal for breeding waders and duck: the depressions formed by the old creeks and salt pans retain water, while the tall, aquatic vegetation and tussocky grazing marsh sward provide nesting cover. Around 100 pairs each of Redshank and Lapwing nest, along with numerous Pochard, Shoveler, Tufted Duck and Gadwall. This is undoubtedly the best site of its type in Essex.

Old Hall is also highly important for passage waterbirds and a visit in late April/early May is virtually guaranteed to produce at least a few Whimbrel (locally known as Titterel in the past). My visit produced a respectable 87, although spring peak counts in recent years have reached 250, making Old Hall an important site nationally for this species. With the scrape on Bale Field in excellent condition, the day’s wader list amounted to 19 species, including single Little Stint, Curlew Sandpiper and Wood Sandpiper, and several Spotted Redshank and Greenshanks.

A year back, I blogged about the Avocets at Old Hall. Well, last year they did well, with 59 pairs on Irongate rearing 50+ chicks. Good numbers appear to be settling this year also. The Avocets moved to Irongate following erosion of the nesting islands on the brackish lagoon at Pennyhole Bottom. These have been restored, and with further work to come, should provide an alternative nesting site, and be in good condition to host autumn passage waders. It’s a long walk around the 11.5 km of seawalls, but there are birds at every turn.

13th May. Old Hall

With 54 pairs sitting on eggs at Old Hall Marshes it might look as if this is going to be a good year for Avocets. But how many will make it through to fledging? If recent years are anything to go by, then very few. When Avocets first colonise a site they typically are very productive but as the years go by, fledging success falls away even if the number of breeding pairs continues to increase. This has been the case at Old Hall, and at many other well known Avocet sites. Some studies show food availability as the key factor, and we know that at Old Hall last year, the average biomass of Avocet food items in the pools was only a small fraction of the recommended level. So this might be the reason. However, we also know that predation is another major factor. Avocet chicks are gobbled up by a variety of predators, not least gulls and foxes.

Whilst both these factors are probably playing a part, the broader issue is that Avocets are an ‘early successional’ species, turning up and doing well at new sites before the habitat matures and brings in other species, such as gulls, or the site productivity (in terms of food availability) drops, or the predators get to know where their dinner is likely to be located. Maintaining Avocets on a small ‘stable’ nature reserve can be difficult, and involve much scratching of heads.

Whilst in such a bout of head scratching at Old Hall, we enjoyed 3 Spoonbills, 35 Whimbrel, 2 Greenshanks, 2 hunting Barn Owls (one catching a vole), 6 or more Marsh Harriers, 2 newly fledged broods of Bearded Tits, and watched the first hatching Avocet chicks. How many will survive this year?