Dave's Birdy Bit - 18th November

The Birdy Bit

This week it was time to clean out the nest-boxes erected around North Plain Farm. The boxes are there to help the local tree sparrow population, which now numbers up to 40 pairs on the reserve. The tree sparrow population has declined nationally by an almost unbelievable 96% over 30 years. They take quite readily to nest boxes which can be an easy way to provide nest sites and monitor the population. However there must also be a ready supply of insects throughout the protracted breeding season (tree sparrows may have three broods, nesting from April through to September) and farm ponds and wetland areas in particular provide rich pickings during this time. As well as nest sites and breeding habitat, declines are thought to be caused by poor over winter survival of adults. Autumn sowing of crops and more efficient harvesting have meant less grain and stubble fields are available for many farmland birds over winter. Provision of arable food sources is important and further areas of ‘wild bird cover crops’ and barley are planned for planting this coming spring.

The boxes have slightly larger holes than those used by great and blue tits and are positioned in large trees with ivy cover or within hedgerows. Around half of the boxes are occupied each year with a pair often producing three broods from the same box. The juveniles from the earlier broods gather at feeding places over the summer and are joined by the adults and last broods later. Moulting takes place through September and October after which the adults begin to roost once more in the colony area with males displaying at nest sites on winter mornings. During the day the flocks will roam nearby, perhaps up to a couple of miles. It is often the youngest birds i.e. the juveniles from the later broods which will disperse and look to set up new colonies if there are insufficient nesting opportunities at the existing site.

Once learned, the harsh metallic ‘chip’ of the tree sparrow is easily separated from the monotonous chirping of house sparrows and birds can be seen towering up out of hedgerows and flying, fast and direct, over the fields. At close quarters, the chocolate brown head and black mark on the cheek separate it from house sparrow.

Over the last few years there have been encouraging signs that the tree sparrow population has begun to slowly increase once more as agri-environment schemes have encouraged the re-introduction of over winter stubbles and spring sown crops.

The wet weather through November has brought water levels up across Campfield Marsh with the farmland at North Plain now supporting hundreds of teal, wigeon, shoveler and pintail. These Arctic and continental migrants are here to spend the winter in our relatively mild damp climate. Whooper swans, here from Iceland, come in to roost on the farmland at dusk and barnacle geese have been feeding on the marsh around the viaduct most days. For a short while, this flock included a snow goose – a rare Arctic vagrant, and an avocet associating with the high tide roost of oystercatchers.

On the Sundays of 6^th, 13^th and 20^th December there will be a pop up RSPB shop in the visitor centre at Campfield Marsh selling a variety of RSPB products including Christmas Cards and other festive goods – why not pop in for a walk and a cuppa?

Dave Blackledge

For more information about Campfield Marsh Reserve and the regularly updated blog, or 200 others throughout the UK visit ^{www.rspb.org.uk/campfieldmarsh}