The Spring Migration

We are delighted to welcome Dr Oliver Fox as a guest writer to our Thoughts, discussing the arrival of different kind of guest checking into Thyme this spring. Every few weeks, Olly and his team of ornithologists, Ian Sheriffs and Noah Walker, wake up in the early hours to make their way to the meadows to understand what birdlife call this small sanctuary their home. From native British owls, herons, ducks and kingfishers, to species that has travelled far and wide to raise their young on the banks of the River Leach.

Dr Oliver Fox, West Oxfordshire Farmland Bird Project

Rising gradually into the cold sky, the spring sun spreads its orange light across the frosted, white landscape of the water meadows. Steam from the river rises in swirls into the dawn air. In the shadows of the bramble patches, the first Robins and Dunnocks awake from their roosts and begin singing from the darkness of the hedgerow to defend their territories.

A ghostly Barn Owl, illuminated from below by the morning sun, quarters over the rough grass in search of its Field Vole prey. In cold weather, the usually nocturnal owls can be seen more regularly before dusk or after sunrise as they struggle to find food. Soon the resident pair in the old Ash tree nest box will have young chicks to feed and they will have to increase the time they spend out hunting over the meadows.

The thick and unwieldy Blackthorn hedgerows have miraculously switched from being impenetrable forests of black twigs to soft clumps of brilliant white blossom. As the sun now hits them they give off their strong perfume and attract the first, resilient insects to come and collect nectar and pollen. Newly emerged queen White-tailed Bumblebees are first on the scene in the morning once the temperature has risen high enough. Dark-edged Bee-flies join them going from primrose to primrose, before alighting on the bright yellow Lesser Celandine flowers that now punctuate the base of the hedgerows.

Although the mornings are still cold, the wind has shifted to blow from the south bringing with it a wave of migratory birds that have been spending the winter in southern Europe or across the Sahara in West Africa. The same dense hedgerows that have been providing food and protection for Reed Buntings and Blackbirds through the winter months, now attract a new assortment of residents, newly arrived from the continent and beyond. The first to arrive in late March are Chiffchaffs, often still braving the coldest mornings. They are joined by Blackcaps in early April and quickly add their warbling song to the dawn chorus. One recent addition to the soundscape at sunrise is the mechanical rattle of the Grasshopper Warbler, a species that that has only recently colonised the water meadows. Now they have found an ideal habitat for breeding they will arrive each spring from their wintering grounds in Senegal and Mali.

Each night of good weather brings more and more new arrivals to the water meadows throughout April. Whitethroats and Willow Warblers appear after epic journeys over desert, mountain and sea from Africa, the males arriving first to start singing on their newly-established territories. Whitethroats seek out thickest hedgerows with bramble and nettles for nesting, while Willow Warblers prefer wetter locations nearer the river where vegetation gives way to the reeds along the river.

Other migrants wait until the chances of overnight frosts have definitely passed and Reed Warblers and Spotted Flycatchers turn up in late April and into May. Throughout the spring months, the water meadows are continually changing with birds either passing through, some making use of the wader scrapes in the middle of the fields, or arriving to breed in the hedgerows and field margins.

One of the early arrivals is hard to miss, a male Cuckoo has returned to Southrop for many years and can be heard patrolling between the large Willow and Ash trees along the river. He covers a large territory and actively chases any other male Cuckoos that appear on the scene. Cuckoos are notorious nest parasites, the females laying her eggs in the nests of other species that then raise the chicks as their own. Therefore, Cuckoos require a healthy population of their potential host species and, in the water meadows, this could include Reed Warblers along the river and Dunnocks in the hedgerows.

Our research team will be onsite at Southrop throughout the spring and summer to record these avian arrivals, where and when they appear and how each species fares during the breeding season. The water meadows and surrounding landscape provides such a diverse and rich habitat for so much wildlife that is always exciting to investigate and document.

Bullfinch

Grasshopper Warbler

Grey Wagtail

West Oxfordshire Farmland Bird Project is run by a small team of volunteers to promote conservation, research and engagement with several local farmers and landowners. The project aims to help turn around the worrying declines in farmland bird populations seen in the UK over the last 50 years, through the promotion of wildlife-friendly management practices, environmental stewardship options and awareness of challenges faced by farmland birds throughout their life cycles. Over the last five years the project has worked on a large number of farms on the conservation of several key species, including Corn Buntings, Yellowhammers, Reed Buntings, Tree Sparrows and Barn Owls.

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