Warden's Diary: Hungry Caterpillars of Weeting Heath

Sophie Harrison, Summer Warden at Weeting

Welcome back to Weeting Heath for which I hope will be a very successful season! For the second year running, NWT Weeting Heath is involved with Breaking New Ground projects. Last season (as part of Wings over the Brecks), Sock Cam enabled us to capture the unique behaviour from our two Godwin chicks, parented by our most experienced birds Cynthia and Hue. This season, with the support of the project, we are introducing a second solar powered camera with a zoom lens. This will enhance our film footage quality, to give us a close up view of a variety of stone curlew behaviour. Stone curlews are very nest faithful and return to the same nesting spot (give or take a couple of metres) every year. Fingers crossed they will make the return journey back from Morocco to breed here again this season.

Weeting Heath is also home to the Lunar Yellow Underwing moth (Noctua orbona). This nocturnal species is recognised by its central crescent and yellow hindwings.  Now confined to the Brecks and a couple of small holdings on the Salisbury plains, it is now a rare moth to find! It is a great habitat quality indicator and requires calcareous sites with patches of well-drained soil, bare ground and tufts of grass. This makes Weeting Heath an ideal habitat for it to thrive.

This year Breaking New Ground (BNG) are holding a series of events across the Brecks. One Thursday evening on 4 February, BNG in partnership with Butterfly Conservation (BC) ran a Lunar Yellow Underwing caterpillar event at Weeting Heath.  Sharon Hearle and Sam Neal delivered an interesting talk about the caterpillars and then it was off to the heath to hunt them down! With torches in hand we went across the heath to see what we could find! Lunar Yellow Underwing caterpillars have a long larva life cycle from November to March, which is also reflected in their long flight period from July to September. By February, the caterpillars are significantly larger (and easier to spot) than if you went caterpillar hunting in November. Optimum temperatures for caterpillar hunting is ideally above 4-5 degrees.

Photo by Matt Blissett

In the Brecks, these hungry caterpillars prefer to feed on sheep fescue, wavy hair grass and brown bent. Avoiding the rabbit holes, we searched the tops of these grasses where they like to perch. However, these caterpillars can be easily confused with Square Spot Rustics, which are nearly identical in colouration. The key difference is that the Lunar Yellow Underwing (LYU) has a curled upright posture, and a chocolate brown underside, whereas the Square Spot Rustic lacks this colouration and is a lot paler. Matthew Blissett our new Breckland Reserves Manager managed to capture the hungry (LYU) caterpillars on camera in their larval stage

However, some of us found all sorts of creepy crawlies hanging out on the tufts of grass that clearly weren’t caterpillars...

Photo by Matt Blissett

This variety of invertebrates provides an excellent food source for our stone curlews!

For more information on other exciting Breaking New Ground events and projects follow this link.

For more information on the important work of Butterfly Conservation go to: http://www.butterfly-conservation.org/

Last season, Terry and Teresa the treecreepers fledged all five chicks from behind the NWT sign on the front of the visitor centre. Both our firecrests and spotted flycatchers also bred successfully in the pines last year. Hopefully they will return again this season. Come and see if you can spot our nuthatches and great spotted woodpecker returning to nest down by the woodland hide. You may be lucky and may even discover a grass snake hiding under one of our reptile tins!

Flocks of lapwing have already started to congregate on the heath, and skylarks have been seen hovering to display and mark their territory. Weeting also hosts a fantastic range of fungi. Down the path to the Woodland Hide, fruiting bodies of Earth Star fungi (Astraeus hygrometricus) have started to develop.

Photo by Sophie Harrison

Earth Star fungi are puff ball lookalikes in their earlier stages. As they grow and the fruiting body develops, the outer tissue of the ball splits to form a star shape, giving them their name. This fungus requires light sandy soils, making Weeting an ideal habitat for it to grow.

Weeting Heath reopens this season on Easter Weekend on Friday 25 March. Come and visit to see what wildlife you can find, and join in with our Easter activities to celebrate the 90th Anniversary of the Norfolk Wildlife Trust!