Llanelli Naturalists Newsletter - Summer 1988
Tony Jenkins
The 1987 season was generally very successful with 89% occupancy of the 27 tit-boxes by Blue Tit (4), Great Tit (3), Pied Flycatcher (15) and Nuthatch (2). Numbers of Pied Flycatcher continue to increase annually, the fifteen pairs in 1987 representing 56% occupancy of all available boxes, compared with four pairs (21%) from nineteen boxes in 1984, the first year of the scheme.
Blue Tits appeared to be on the increase again, four pairs breeding in 1987, although no discernable pattern of colonisation was evident during the period 1984-87. Three successful Great Tit broods represented the highest number colonising boxes to date, although Redstarts continued to exhibit a preference for natural nest sites. Only one box has been occupied by Redstarts during the four years of the scheme to date.
An estimated 124 nestlings successfully fledged from 24 boxes in 1987, comprising 62 Pied Flycatcher, 33 Blue Tit, nineteen Great Tit and ten Nuthatch. Overall combined breeding success for tits and Nuthatch was high (83%) with 62 birds fledging from the 75 eggs laid. Hatching success for all boxes was also high (86%) with a total of 157 young hatched from the 182 eggs laid, although only 124 fledged (79%). This lower fledging success was almost entirely due to the nest deaths and brood failures of some Pied Flycatchers.
The ringing scheme continued in 1987'with eleven adult female and 29 nestling Pied Flycatchers and six Nuthatch nestlings being ringed. O4 particular interest was the recovery of an adult female Pied Flycatcher on 10th June 1987 (ring no. B657193) which had been ringed as an adult at Gelli Aur on 8th June 1986. This was the first recovery of a Pied Flycatcher previously ringed in the park.
Although more Pied Flycatchers occupied boxes in 1987 as compared to previous years, breeding success was lower, due to nest deaths (including one complete brood) and possible predation of two boxes. Of 107 eggs laid, 86 hatched (80%), although only 62 (58%) successfully fledged. Clutch sizes were generally higher than those for earlier years, with an average size of 7.1 in 1987 compared with 6.3 in 1986. In 1985 only one Pied Flycatcher laid a clutch of seven eggs but this increased to three in 1986. However, during 1987 eleven laid seven egg clutches and three laid eight egg clutches. Second broods were not recorded from any boxes in 1987 and it is intended to increase the number of tit boxes from 27 to thirty for the 1988 season.
Clutch initiation (first egg date) was calculated for Pied Flycatcher Broods in 1987 and compared with those for 1985 and 86. Clutch initiation was generally two weeks earlier in 1987 with fourteen pairs completing first egg laying by May 14th. This temporal shift in the pattern of clutch initiation was also recorded further north at Newbridge-on-Wye where Pied Flycatchers laid earlier than at any time during a thirty year study of the species at Llysdinam. The earliest first egg date recorded by Dr.Slater of the Field Centre was April 30th - quite exceptional!
