Jun 04 2018

The Return of the Ethereal Nightjar

Nightjar

Rare glimpse of a nightjar during the day. Picture captured by Rob Solomon.

Late May heralds the arrival of one of Britain’s most enigmatic birds – the ethereal Nightjar, the first of which arrived on the Special Protection Area about two weeks ago. Weighing only 70g and having travelled close to 10,000 miles or more since they were last on our heaths only adds to the legend of these magnificent creatures. Nightjars show high site fidelity meaning they return to the same breeding site year after year, with their wintering grounds across Sub-Saharan Africa (Kenya to South Africa, Northern Namibia/Botswana and the Democratic Republic of Congo). With close to 350 pairs breeding on the Thames Basin Heaths, the Special Protection Area is an important area for this nationally important species. Our fascination with Nightjars goes back centuries, and even millennia. Many people will have heard of the Goatsucker superstition, with the first part of the Latin name literally meaning Goatsucker and this actually dates back to Aristotle. Many names and folklore are attached to the Nightjar and it’s not difficult to see why, the combination of its amazing other worldly song, appearance and nocturnal habits all fed the stories told about these beautiful birds. Associations with mischievous spirits, the souls of children and even the foretelling of death have all been attributed to them since ancient times.

Heath at dusk

The heath at dusk can be magical. Taken by Warden Sarah.

The heathlands at night don’t only play host to Nightjars, another bird just as weird and wonderful you may see at dusk is the Woodcock. The Woodcock is a bulky almost ‘pot-bellied’ looking wader that is almost exclusively crepuscular, active at dawn and dusk, and usually only seen during the day when flushed from a roosting site. They perform their classic ‘roding’ display over woodland edges and across heathland, making an orr, orr, orr, pist kind of call as they twist and fly over their territories. A study of spectrograms of the vocalisations of male Eurasian Woodcock showed that 95% of calls could be attributed correctly to individual birds, and concluded that counting ‘roding’ males was a suitable method of monitoring the population. One really peculiar behaviour of Woodcock, rarely ever observed, is the ability of the threatened mother bird to fly whilst carrying small chicks between her legs, body and tail, in her claws or on her back.

Other wildlife highlights from the Thames Basin Heaths this last week include an abundance of Cuckoo sightings and calls across the Special Protection Area. Cuckoo, like Nightjar, are long distance migrants that return to the UK and other parts of Europe between late April and early May. Recent tracking studies have started to reveal the mysteries of their migration and how they spend their time throughout the year. Although it has long been known that Cuckoos leave the country earlier than most, courtesy of their parental techniques, but these GPS trackers have revealed they leave as early as June! This is much earlier than was expected with the earliest leaver leaving on the 3rd June, with around 50% of the tracked Cuckoos leaving before the end of June. This means that our Cuckoo’s spend only around 15% of their time in the UK, 47% spent in Africa and 38% spent on migration, which is amazing considering the energy expenditure required to cover this distance. One of these Cuckoos, named Chris, a 4 year old male, as of 2014, had been tracked for 3 years and in this time had covered 45,000 miles.

Green Hairstreak butterfly captured by Warden Michael

Green Hairstreak butterfly captured by Warden Michael.

The continued good weather is having a positive impact on the local invert population with the numbers and variety of butterflies, moths, bees and beetles continuing to increase. Holly Blues, Dingy Skipper, Meadow Brown and Green Hairstreak, amongst others, have all been seen across the Special Protection Area. The Green Hairstreak is the only green coloured butterfly in the UK, although this green colour is only on the undersides of the wing with the top of the wings been a dull brown colour. It is the only hairstreak to hibernate over the winter as a chrysalis. As with many Lycaenids (Blues, Hairstreaks and Coppers) it has a mutually beneficial relationship with ants, in return for protection the chrysalis provides the ants with secretions using an attractive sound to draw them in. The ants often bury the chrysalis or even take it down into their nest over the winter.

Warden Conor

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