A Wild Goose Chase

The lake was a mirror image of the sky above. A patchwork of blue and white, with a margin of deep green. It had been a hot and sunny morning at Cranwich, working through the latest Constant Effort session for birds. All the usual suspects were in attendance. Young Blue Tits, fluffy and yellow, accompanied by adults beginning their wing moult. A smattering of adult Reed Warblers requiring one of our colour rings and plenty of fledged Reed Warblers which to Dave’s relief had rings on already. Plus plenty of others, from a Jay to a Song Thrush, Reed Buntings to Chiff Chaff.

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Once the nets were down, we did not however immediately head for home, but made our way with wire mesh, hammer and wooden posts to a small strip of land between two of the larger lakes. Here a very narrow and shallow ditch connects the two, and is used as a crossing place for water fowl that were now beginning to collect on the lakes. Ducks and geese both congregate on the lakes at this time of year, and for the geese in particular it is to moult their flight feathers. Unlike small passerines that must retain the ability to fly or face being eaten or starvation, ducks and geese can easily walk out onto grassy banks or fields, or feed among reeds and marginal vegetation without the need to fly. Of course, they are still vulnerable to predators but that is where eclipse plumage, safety in numbers and the ability to paddle out into the middle of a deep lake comes into play.

Geese are of course not necessarily one of the most glamourous groups of birds and often divide people’s opinion like urban gulls. Perhaps not so helpful is the semi-tame, uninspiring nature of many populations of both the native Greylag Goose (ancestor of most domestic geese) and the introduced Canada Goose (although one could argue the pleasure seen from feeding ducks and geese by little ones goes a long way in appeasing such grumbles).

There is something wonderfully special about truly wild geese that migrate thousands of miles and then come whiffling out of the sky….

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Pink-footed Geese in flight

Still back to our introduced and almost feral geese trundling around the lakes, rivers, reservoirs and gravel pits of southern England. Its tempting to think they stay in the same place year after year, but no one really knows for sure. What is known is that they can cause serious habitat degradation in certain locations like the Broads in Norfolk, especially when flightless and moulting their feathers. Understanding the reasons behind their movement can help improve the situation for geese, people and other wildlife reliant on quality habitat.

In 2012, the British Trust for Ornithology started a project, initially as part of the Hickling Broad Project, to add uniquely coded plastic neck collars to Greylag and Canada Geese to track their movements.

Neck collars are a completely safe method for marking large geese and have been widely used in previous studies especially with migratory geese. They allow geese to be identified without recapturing them, both on land and in water where their legs are submerged. Due to their large heads there is in fact plenty of space around the collar itself.

The BTO relies on members of the public, birds, staff and volunteers to report their sightings of neck collared geese, and have had some interesting movements over the years.

Back to our hot, sunny morning at Cranwich and using the tools and materials we had, we built a corral surrounding the little ditch connecting the two lakes. Then with people strategically placed around the end of the lake to discourage escapees, Lee braved the water in wetsuit and inflatable canoe (but not oars, a branch will do) to herd the small flock that had gathered.

It is a careful process. Too quick and the geese will scatter, too slow and they will baulk at the sight of the corral. Still, while certainly we lost a few through the makeshift fence and around the edges, a catch of 12 geese (9 Greylag and 3 Canada) was not bad for out small team.

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Greylag Goose with neck collar – Photo by Mark Robinson

Its then a question of attaching a metal ring to the leg and slipping on the neck collar, before each one is returned to the lake. Where they go is unknown… for now.


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