Cuckoo - 2003-07

Cuckoos were found in only 80 tetrads between 2003 and 2007 compared with more than 200 tetrads 20 years ago (a decline of about 62%). All atlas categories registered huge declines.

What is most apparent is that the population is now reasonably widespread only in the open country of the Preselis and on the St. David’s peninsula. Their recorded distribution here in 2003-07 was fairly similar to that of the 1984-88 atlas period. Both these areas probably support potentially good populations of ground-nesting host species (such as Meadow Pipit). They have all but disappeared as a regular breeding species in the south of the county and along the Teifi valley bordering Ceredigion. Surprisingly, Cuckoos appear to have declined along the Castlemartin peninsula where there are still good populations of potential host species within the extensive Military Range.

In 1984-88 it was assumed that the Pembrokeshire Cuckoo population was about 210 pairs (approx one pair per occupied tetrad). The most recently available figures from BBS (Wales) indicate that there has been a 52% decline in the Cuckoo population index between 1994 and 2007. According to a BTO Report (Say Goodbye to the Cuckoo), the national Cuckoo population showed a decline of more than 60% across the country during the period 1981-2006. Because of this population fall, Cuckoos have been added to the “red-list” of birds of conservation concern. The decline in the number of tetrads in which they were found in Pembrokeshire (62%) very much mirrors the national picture over the same period.

If the decline in Pembrokeshire is between 52% (based on the Welsh BBS results, albeit from only 56 sample sites across of Wales) and about 62% (based on the decline in tetrad distribution) – this would suggest a current estimated population of no more than 80-109 pairs, now largely confined to optimal habitat in the north of the County. Because Cuckoos calling in early spring may still be on migration, it is probably better to consider only those tetrads with probable or confirmed breeding evidence; this suggests a population of no more than 70 pairs in the recent atlas period.

The Cuckoo may be the victim of a variety of factors. They may be struggling to find enough food during the breeding season here in the UK and also suffering a similar fate on their wintering grounds in Africa. Declining habitat quality may also be affecting host species such as Meadow Pipit and Dunnock (species also showing signs of decline nationally) and thus affecting the ability for Cuckoos to rear a sufficient number of young each year needed to maintain a stable population.

Bob Haycock

 

Fieldwork 2003-07 (based on 490 tetrads)

Red = breeding confirmed = 1

Orange = breeding probable = 69

Yellow = breeding possible = 10

Total tetrads in which registered = 80 (16.3%)