The Potteric Carr hat trick

Earlier last year, something very special happened at Potteric Carr nature reserve… Andy Dalton, Gateway Manager, tells us more...

Recently I was sitting in one of the hides at Potteric Carr when I heard a clear and relatively loud “pinging” noise, like the sound of a bicycle bell, coming from the near by reeds. This evocative sound gave away the presence of a bearded tit, a recent colonist at Pottreric Carr nature reserve.

This species’ successful breeding completed the “big three” we have been hoping would make Potteric Carr their home since the creation of Huxterwell Marsh back in 2006. Both marsh harrier and bittern have bred successfully every year since 2014, with between one and two pairs of each breeding at the reserve.

Bearded tits have proven to be trickier to attract all year round. Up until 2019, we had only recorded the occasional bird in spring and autumn. By closely observing the behaviour of all three species, we have been able to confirm that in 2020 they have all successfully bred at Potteric Carr for a second consecutive year.

This is great news as it demonstrates that the reedbeds across Huxterwell have matured sufficiently to attract a full range of bird species. It also establishes Potteric Carr within the wider landscape, and as part of a network of nature reserves and protected areas across the Humberhead Levels and Dearne Valley that support these species and the ecosystem in which they can thrive. Hopefully in the future, the small colony of bearded tits will grow further, both at Potteric Carr and beyond.

Potteric Carr is an important nature reserve nationally for both the bittern and the marsh harrier, as both species start to recover from historic low numbers across the country. The breeding success of these birds at our Doncaster reserve demonstrates how we can, through concerted effort to provide suitable space and habitats, encourage the recovery of iconic, though still vulnerable, species.

Our 'big three' species

male Bearded Tit © Darren Ward 2020

male Bearded Tit © Darren Ward 2020

Bearded tit

Bearded tits are small, long-tailed, active birds, just slightly smaller in size than a robin. They are often seen in a fast, whirring flight between areas of reed, appearing almost mechanical in nature. Their name is also not totally descriptive, as rather than a beard the males exhibit a rather fine moustache pattern on blue-grey heads! They are handsome birds with an overall strong golden brown plumage. Sometimes referred to as ‘bearded reedlings’, they are not actually related to the more familiar great or blue tits often seen in gardens.

Approximately 600 pairs breed in the UK each year, although they are prone to decline in harsh winter years. These birds have a rather interesting feeding behaviour, eating mainly insects during the spring and summer before switching to a more vegetarian diet over winter. They require small particles of grit to help them digest the seeds (usually from common reed) they eat, so we often put out ‘grit trays’ at Potteric Carr to supplement the natural supply

Bittern © Freddie Oxley 2020

Bittern © Freddie Oxley 2020

Bittern

Bitterns are related to herons, and are slightly smaller than the familiar grey heron. They are a wonderful mixture of golden brown, black and lighter straw-coloured feathers, providing a very effective cryptic camouflage. Bitterns feed mainly on the edge of reed fen, eating a variety of fish, insects, amphibians and smaller birds, particularly small chicks. Bitterns make the most fantastic “booming” sound to attract a mate and declare their presence to rivals. A sound that can be heard for several kilometres in the right conditions!

Bitterns are still rare in the UK. They became extinct in the late nineteenth century, only slowly recovering in the early part of the twentieth. After a post war revival, the population crashed and, by 1997, there was just 11 “booming” males left in the UK. With a united effort, conservation organisations have created more suitable habitat to attract bitterns to breed. The latest survey of males has revealed an increase of around 200!

Marsh Harrier © Keith Horton 2020

Marsh Harrier © Keith Horton 2020

Marsh harrier

A large raptor with a wingspan up to 1.2 m in length, marsh harriers are real lowland birds, favouring large, open landscapes like reed fen. Males and females have different plumage: the male has a striking mixture of grey, red-brown and black feathers, whereas the female has a dark chocolate brown overall look – with a light “cream crown” that sometimes extends onto the shoulders and throat. Marsh harriers will eat anything available to them, from small mammals to amphibians and reptiles, but small birds – particularly waterfowl – are their preferred food.

The breeding history of the marsh harrier mirrors that of the bittern. Persecution and habitat loss led to its extinction around the turn off the twentieth century; there was a small post-war increase, but then the population fell to just one pair in 1971. Thanks to conservationists, numbers started to slowly increase again, with around 100 pairs recorded by 1990. There are now thought to be over 425 pairs in the UK.