Forest Monkeys reveal secrets

The Dutch name for Little Bittern is Woudaap, which in direct translation means Forest Monkey.  Last weeks work involved a great deal of nimble movement through reedbed ‘forests’, culminating in the Somerset Forest Monkeys revealing some of their secrets.

We started with a good deal of thrashing about in the reedbeds at Minsmere.  Thinking about climate change, the impact of too many Red Deer, and natural succession in an ageing reedbed.  How are we going to manage this site over the next 25 years?  Nothing beats getting into the habitat and experiencing it close-up to understand what needs to be done.

Then on to Snape, where new wetlands are being created.  A bit of electro-fishing to understand how the fish populations are developing, then a look at the area currently being created to add a few tweaks to the design; imagining yourself in a metre of water surrounded by reeds and thinking what features would attract a feeding Bittern or a Great White Egret.

Then down to Ham Wall, where after a summer of meticulous recording by a superb group of volunteers and local birders, we soon homed in on the Little Bittern nesting and feeding sites.  Water depths, edge profiles, reed characteristics were all recorded and some electro-fishing revealed the secrets of the Forest Monkeys favoured feeding areas.  Such details will be invaluable in creating similar habitat elsewhere.

One interesting fish caught in some numbers at Ham Wall was the Moderlieshen or Sunbleak Leucaspius delineatus, a non-native species that has a highly developed life history strategy. The majority of cyprinid fish species take 2-4 years to become sexually mature and spawn just once a year. The females scatter many thousands of eggs over aquatic macrophytes or gravel,and these are then left unguarded and vulnerable to predation.  Unusually for cyprinids, the Moderlieshen become sexually mature at one year old and are batch spawners, with females laying several batches of eggs, between April and July, which are guarded by the males until they hatch. They were first recorded in the Somerset Levels around 1990, their origin unknown but likely to have arrived via some fish stocking by anglers.

Photos above - Moderlieshen, Little Bittern nest.

Landing pad for Little Bitterns

“Jig jig jag jag, ping ping, boom, woof....woof....woof”.  Singing Reed Warblers everywhere, Bearded Tits feeding young and I can hear six booming Bitterns around me.  A Great White Egret flies by and a hidden Garganey rattles from a nearby reedy pool.  As it gets dark a Spotted Crake whips from the ditch next to the path.  Where am I?  Another foreign jaunt?  No, in deepest England on a wetland that didn't exist 20 years ago.  Woof....woof....woof, Oh, did I mention the singing Little Bittern.

Where wetland colonists are concerned, a recent study has shown that the six species that have established populations in the UK since 1960 all started to breed in protected areas.  Furthermore we know that larger sites are more likely to attract colonising species.  Such areas have been described as ‘landing pads’ for colonising species, allowing them to become established before viable populations spread out.  Ham Wall (and the wider Avalon Marshes in which it sits) is living proof of this as we hopefully see the first stages of Little Bittern establishing a regular population in the UK.  Climate change analysis predicts that Little Bittern may colonise southern England. Although populations on the continent declined sharply over recent decades, the cause of which is considered to be drought conditions in the wintering areas, some recovery has been evident in the last ten years.  The Ham Wall birds returned this year as usual in early May and feeding flights will hopefully be evident soon.  The Avalon Marshes ‘heron hot spot’ is rapidly taking over from Suffolk as the key area for (Great) Bitterns in the UK, with 35 boomers this year.  At Ham Wall there are 12 boomers with at least 5 nests pinpointed so far from feeding flights.  

Previously I had looked at the developing reedbed ‘rejuvenation’ area, which as predicted, attracted good numbers of waterfowl in its early flooded phase.  A singing Pied-billed Grebe, along with Ferruginous Duck and Ring-necked Duck, were the highlights.   There were still plenty of duck on show during my visit – Pochard, Tufted, Shoveler, Wigeon and a couple of Garganey - but high water has pushed any waders to the margins.  Just a dozen Black-tailed Godwits, a few Redshank and a Whimbrel were visible.  However, as water levels drop by late summer, the area should increasingly attract a good range of autumn passage waders and waterbirds.

below: rejuvenation area and reed-nesting Grey Herons