This week saw the launch of the RSPB Centre for Conservation Science – and one of the strongest foundations of RSPB Science is research into the causes of bird population declines: the diagnosis, in medical parlance. Through this process we now understand what many of our rare and threatened birds need to thrive and survive, allowing us to develop effective, practical conservation solutions. But some birds still require the detective approach. One of these is the hawfinch. Research Biologist Will Kirby picks up his deer-stalker and magnifying glass and gives the low-down on looking for clues:
The UK’s largest finch, bright colours, powerful bill for opening tree seeds, difficult to find and declining at an alarming rate, that’s Hawfinch in a (cracked) nutshell. Latest estimates suggest a UK breeding population of only 500-1000 pairs (similar to Cirl Bunting or Corncrake). The 2007-11 Bird Atlas estimates a 76% reduction in breeding range over the last 40 years, most of which has occurred since the late 1980’s. Long gone are the days when they were considered pests in the cherry orchards of Kent...
Very little research has been undertaken on UK Hawfinches and there is no consensus on what might be driving the declines. Some ideas put forward at a 2011 workshop of experts convened by RSPB included: low nesting success (possibly predator induced); a shortage of over-winter food and changes to habitat, though evidence to support any of these is lacking.
Studying breeding Hawfinch was always going to be a tricky proposition: they spend most of their time hidden in the upper canopy of mature woodland, their song and calls are relatively indistinct, they are not especially territorial, their nests can be 20m+ in height – and there aren’t many left! However, we had to start somewhere and in 2012 RSPB and Natural England began the current study. Our first field-season was spent mapping and comparing habitat in areas which had either lost or retained breeding pairs between the current and previous Bird Atlas periods, in counties as far apart as Cumbria and Kent.
In 2013 we moved the study on to start investigating the birds themselves and with help from local Ringers in the Wye Valley, female Hawfinches with caught and fitted with radio-tags. Following these birds has started to provide the first information on how they use their woodland habitat and shown that they are extremely mobile, regularly travelling several kilometres between feeding and breeding sites. One female was found to be nesting 17km from the catching and tagging site whilst another moved 3km between her first (unsuccessful) nest and a second attempt.
This coming season we are planning to build on the small sample of birds we tagged last year and with the benefit of experience, hope to follow more birds for longer and to find more nests to monitor. We are still at a very early stage in the process of attempting to diagnose the causes behind the Hawfinch decline and even if we can, finding solutions is not going to be easy. But at least we have made a start...
For more information on our hawfinch work, ‘diagnostic’ research on other species, and whole programme of science, from national and international monitoring schemes to testing practical conservation solutions, please visit the RSPB Centre for Conservation Science website.
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