Greenfinch – 2021 breeding – can you help?

Chloris chlorisLlinos WerddBreeding resident and passage migrant

The 1984-88 map of greenfinches breeding in Pembrokeshire showed that greenfinches occupied 55% of tetrads in the county.  The 2003-07 map indicated an increase to 78% of tetrads.  Since then, the story is all downhill, as shown here by the results of the Breeding Bird Survey.

The increase between the two atlases may have been fuelled by the increase in feeding birds in gardens leading to better winter survival.  However, that same phenomenon may have led to the subsequent decrease as a parasite called Trichomonas gallinae transferred from pigeons, birds of prey, and domestic chickens and turkeys to smaller birds such as finches.   The resulting disease, Trichomonosis, spreads rapidly via food and water contaminated by infected individuals – so garden feeders, water for drinking and bathing, anywhere that birds congregate is a potential problem.

Greenfinches are still widespread in Pembrokeshire, but are thin on the ground.  Breeding records seem particularly scarce.  The map above shows where greenfinches have been recorded in April-July 2011-2020 according to records in BirdTrack.  The black squares indicate that the observer recorded definite evidence of breeding  – nests, birds carrying food, recently fledged youngsters (being fed), for example. 

The easiest way to do this, is for everyone to note where they see greenfinches in April, May, June and July, and add those records to BirdTrack.  In BirdTrack you can pinpoint a location on a map or aerial photo. Then when entering details, click on the ‘highest breeding evidence’ box and select the appropriate code. Many thanks to the observers who are already collecting this information.

Greenfinches usually produce a second brood, so there is plenty of ‘season’ left for finding them.  

If you really don’t want to use BirdTrack, then there is the WWBIC recording scheme either on-line or via their app (part of iRecord) where you’ll have to state in the comments field what you have seen. If all else fails, you can email me, but remember to include the site name, the site grid reference, and the breeding code.

The map will be updated in early July, though records not submitted through BirdTrack may take longer to incorporate so there will be another update later in the year.

More about the Greenfinch in Pembrokeshire

Wren – 2019 BBS

Troglodytes troglodytes – DRYW – Breeding resident

The wren is a pretty ubiquitous species across Pembrokeshire, it having been recorded in almost every tetrad in the 2003-07 atlas.  More than that, the BTO Atlas 2007-11 shows that Pembrokeshire is one of the most densely populated areas of the UK as far as wrens are concerned.

While it is basically a bird  of deciduous woodland, it is an adaptable species also common in scrub, pastoral farmland, villages, towns, and even coniferous woodland.  So, not surprisingly it is recorded in virtually every square covered by the Breeding Bird Survey in the county.

With less than 15 squares surveyed before 2002, the results could be expected to be a little erratic, while the apparent dip in the population in 2001 was the result of only two squares being surveyed during the foot-and-mouth outbreak.  Nevertheless, the population density seems to be increasing overall.

Like many small, but warm-blooded, creatures, the wren is susceptible to cold weather, so it should be expected that breeding populations will be reduced after severe winters.  The graph shows the short-term effects of cold conditions in 1995/96, 2009/10, 2010/11 and 2017/18.  These are evident on the Breeding Bird Survey index for both Britain and for Wales, yet in Pembrokeshire there is an unexplained dip in the summer before the 2017-18 winter and an increase afterwards. 

In the longer term, the population in Wales has increased by 9% between 1995-2018 (Harris et al. 2020), and in Pembrokeshire it is showing a similar trend.

Skokholm

While Skokholm isn’t part of the BBS network, all the breeding birds there are monitored intensively each year.

Wrens first bred on the island in 1988, and numbers have been increasing ever since.  In 2018, 63 territorial males were mapped.  Perhaps surprisingly, given the snow and freezing conditions prevalent during February and March that year, the total was five up on that of previous year and two up on the 2016 Skokholm record.  The reason for this substantial increase in the number of territorial males is unclear.

Annie Haycock (BBS & WeBS local organiser)

References:

BALMER D, GILLINGS S, CAFFREY B, SWANN B, DOWNIE I, FULLER R. 2014. Bird Atlas 2007-11: The Breeding and Wintering Birds of Britain and Ireland.  HarperCollins.  UK

BROWN R & EAGLE G, 2018 Skokholm Annual Report. Wildlife Trust for South and West Wales.

HARRIS S J, MASSIMIMINO D, EASTON M A, GILLINGS S, NOBLE D G, BALMER D E, PEARCE-HIGGINS J W & WOODCOCK P. 2019. The Breeding Bird Survey 2018. BTO Research Report 717. British Trust for Ornithology, Thetford.

More about the Wren in Pembrokeshire