Counting Cuckoos

Senior Times

Dick Coombes tracks the fortunes of Ireland’s breeding birds.

Birds are everywhere and we all, consciously or otherwise, have at least a passing awareness of them – the welcome chatter of newly arrived Swallows in spring, the confiding Brent Geese at the local golf course or the unmistakeable song of the Cuckoo while holidaying in the west. Birds are an integral part of the countryside and enrich our experience of the great outdoors.  But, like the proverbial Canary in the mine, wild birds can have a more practical function for us humans – they are valuable indicators of the health of the environment.

The decline of any species is a cause for concern and in some cases, dramatic changes in abundance or distribution are readily noticed by “non-experts”. Comments such as – “You don’t hear the Corncrake round here anymore” or “Skylarks have gone very scarce in the last few years” would be typical and perfectly correct observations likely to be made by even those with no birdwatching experience. But in this day and age, solid evidence of such declines needs to be based on more than anecdotal impressions and it is also vital that they are quantified with a degree of scientific rigour.

The Corn Bunting, once a widespread farmland bird, went extinct as a breeding species in Ireland during the 1980s.  Several other species could be heading the same way – Barn Owls are only found in a fraction of the sites they formerly inhabited, the demise of the Corncrake population has been linked to changing, more intensive farming methods and the Grey Partridge is only hanging on by a thread, probably for similar reasons.  Other species like the Yellowhammer are known to have a high dependence on arable farmland and today their range is mainly confined to the cereal growing regions of the southeast – the rest of the country has almost entirely gone over to pasture. 

In the UK, where pressures on the countryside have also caused serious declines in recent decades, the British Trust for Ornithology (BTO) has been monitoring their breeding bird populations for some 45 years. Clearly it was high time we had an early warning system in place in this country.  So, in the spring of 1998, the Countryside Bird Survey (CBS) was launched.  It is a joint project between BirdWatch Ireland and the National Parks and Wildlife Service (NPWS). Using tried and tested survey methods devised by the BTO, the CBS is now well-established as Ireland’s monitoring watchdog, keeping tabs on Irish breeding bird populations. The scheme is a long term programme which hopefully will continue indefinitely.

Now, to establish whether the population of any bird species is declining or increasing, or indeed remaining stable, some counting needs to be done!  Obviously, it would be impossible to count all the birds in the country even once, never mind every year. So a sampling system, which covers a range of habitats and geographical locations, needs to be devised. In the CBS, a minimum of 300 sample sites (1km squares) across the country are visited twice each spring.  Because bird surveys of this nature usually require the help of a large number of people over a wide area, they are designed to be simple to follow and enjoyable to do.  This seems to work with the CBS as over 250 volunteers and NPWS Conservation Rangers take part every year – more or less without a whimper! 

The counting method is straightforward – a ll birds seen and heard are noted down as the participant walks along two 1km routes (or transects).  Consistency is the key to accurate monitoring, so the same routes are walked year after year, at the same time of day, on roughly the same dates and in the same “reasonable” weather – this bit is not easily achieved these days.  It might initially alarm some people to read that counting has to be done between 06.00 and 09.00hrs, but they quickly find that this is definitely the best part of the day and you never tire of the dawn chorus.  

On 1st April this year, the CBS embarked on its 12th season and just as participants were psyching themselves up for another round of early morning walks, BirdWatch Ireland completed its analysis of the first ten years of the survey and published its findings in a major new report.  This marks a significant milestone – never before has it been possible to produce population trends of our breeding birds over such a time span and these are already being used for developing government conservation policy.

Altogether, some 145 species were recorded in the 10-year period, including 18 species which are of conservation concern in Ireland. The survey has revealed that Wren, Robin, Blackbird and Chaffinch are the most widespread species, occurring in 90% of the country’s sample sites – these species are clearly adapted to survive in almost any habitat.  Rook, Starling and Wren were found to be the most abundant species. 

So how are the various species doing regarding population trends?  While there have been both winners and losers, overall, most of our breeding birds are faring reasonably well, especially pigeons, warblers, tits, finches and buntings, with most remaining stable or even showing an increase over the ten years. But it must be pointed out that as the survey only began in 1998, many of these may only now be starting to recover from the massive declines which occurred during the 1970s and many species may not yet be back to their former strength.

On the down side, some species continue to show declines, especially Kestrel, Swift, Skylark and Mistle Thrush. These farmland birds have been affected by changes in agricultural practices such as increased use of pesticides and fertiliser. Climate change has also undoubtedly played a role.  Swifts are aerial feeders and would be severely affected by the wet and windy summers we have been experiencing lately.  Skylarks feed on spilt grain and small weed seeds in stubble fields during the winter. More and more, stubble is being ploughed in during the autumn in order to sow an early crop of cereal.  This practice has drastically reduced the Skylark population in Britain and we may have a similar problem here.

The Countryside Bird Survey is a fine example of how amateur naturalists can make a huge contribution to science and conservation, simply by putting a nice walk in the countryside to even better use beyond getting exercise and fresh air.   It simply would not be possible to gather enough data to produce meaningful results without the assistance of hundreds of dedicated observers.  Let us hope the enthusiasm doesn’t wane, as this is only the first stage in bringing about conservation measures to protect our countryside birds.

Anyone wishing to find out more about the CBS should visit www.birdwatchireland.ie.  New participants are always welcome, so if you are confident in your bird identification skills and would like to help, please contact Dick Coombes, the CBS Co-ordinator in BirdWatch Ireland, tel: 01-2812408 or email rcoombes@birdwatchireland.ie  The season runs from April to June.

Copyright ©2010, Senior Times.