Dee Estuary warden, Al gives an insight into one of our much-talked-about recent stars at Burton Mere Wetlands.
What's that wigwam?
Up to six bearded tits have decided to call Burton Mere Wetlands home since October, following a periodic "irruption" of them to various new parts of the UK. They have been hanging around the reedbed, often offering fantastic - if occasional - views to many patient visitors. We have been hoping that they will hang around until the spring which would offer the possibility of the first ever breeding bearded tits at Burton Mere Wetlands!
Spring is almost upon us, and they are still here! So we are trying to persuade them to hang around by offering them their own, specially designed nestbox. The design was patented at Leighton Moss by former warden David Mower:
David Mower with reed wigwam at RSPB Leighton Moss (Ben Hall, rspb-images.com)
A tightly packed bundle of reed, tied at both ends, and a stake through the middle. We then pull the reed out from the middle to form the shape, and stuff reed seed heads in the centre to give them some nice bedding. Whilst working at Leighton Moss, I learned the art of how to make these wigwams, and made hundreds!
We have had to modify the design a little here at Burton Mere though; you should usually harvest green reed so that it is pliable enough to shape the wigwam – otherwise it just snaps. Our birds didn’t turn up until autumn, so we were too late! I used some sea-club rush that was tough enough to do the job even when dead.
Reed wigwams and male bearded tit (A.Grubb)
Bearded tits usually nest on the ground, in a small cup of reed seed and grasses. However at Burton Mere Wetlands, we keep the reedbed as wet as we can through the spring, as it acts as a valuable reservoir for our wet grassland for breeding wading birds. This means there are very few suitable places for the birds to nest naturally. By providing them with wigwams, they have sheltered nest sites, safe from flooding.
A natural bearded tit nest (A.Grubb)
We have put several wigwams out in the reedbed, including the one close to Marsh Covert hide for visitors to see one in the flesh. Hopefully they will be used; as you can see from the picture above, the birds at Leighton Moss love them!
We have had several visitor enquiries and requests since the birds first arrived to install “grit trays” on the reserve, as they do at RSPB Leighton Moss (where bearded tits have been resident since the 1980s).
Grit tray at RSPB Leighton Moss (Ben Hall, rspb-images.com)
Bearded tits change their diet as the seasons change; invertebrates in the spring and summer, shifting to reed-seed in the autumn and winter. In order to digest the seed properly, they must fill up their gizzard with grit, which grinds the seed down like a sort of “mill” (in a similar way to game birds). In the spring and summer, when they are feeding on insects, their gizzards are empty, so when the time comes for them to shift their diet (around October), they must take on grit to fill those gizzards. They can gather this grit from anywhere, and visitor footpaths on nature reserves seem to work perfectly.
When the numbers of birds built up at Leighton Moss in the 1980s, the wardens (John Wilson and David Mower) noticed the birds taking on grit from the footpaths. Whilst this was a fantastic visitor spectacle, it also presented a problem: whenever anyone wanted to walk down the path, the birds were disturbed and flew off elsewhere. They developed a simple, but ingenious idea: a “grit tray”, just off the path, where the birds could still take on grit, but would not get disturbed by walkers. These grit trays now provide an amazing spectacle; offering visitors the opportunity to watch the birds “gritting” for long periods of time, within 20-30metres!
Male bearded tit on grit tray at RSPB Leighton Moss (Mike Malpass)
The reason we haven’t installed any of the trays here at Burton Mere, is because our birds only turned up in November – they had already filled their gizzards up! They do still need to top up with grit occasionally, but they will just take small amounts from the paths periodically.
As we enter spring, they will shift their diet back to invertebrates and not need any grit. If we are lucky enough to have them hang around until Autumn, we will install some grit trays and see whether they use them then.
Thank you for the update, Al. It is great to read about the steps being taken to encourage the Bearded Tits to stay and breed. Let's hope it pays off.
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