Patrick Smiddy

The breeding biology of the Dipper Cinclus cinclus in south-west Ireland

The breeding biology of Irish Dippers was studied over 12 years. A total of 501 nests was located, mostly at artificial sites, notably bridges. Irish Dippers start breeding earlier, lay fewer eggs, fledge fewer young and have fewer second broods than most other populations. The mean clutch size was 4.16 (±se 0.03) and the mean brood size at fledging was 3.48 (±¸se 0.05) per successful pair. The breeding biology is compared with other populations and some differences are highlighted.

Biometrics, growth and sex ratios amongst Irish Dippers Cinclus cinclus hibernicus

Biometrie data of Irish Dippers were investigated over two years. Wing length, tarsus length and weight were measured from fully grown and nestling birds across a number of sites in southern Ireland. Fully grown birds were found to be sexually dimorphic for wing length, tarsus length and weight. The degree of sexual dimorphism was less than expected, females being larger than reported from most other studies. Weight varied little between seasons, and the annual pattern of weight change was less than that shown for other studies. Nestling growth rate was similar to that of Welsh Dippers. These results are discussed in the context of the ecological niche of the Irish Dipper.

Time of roosting of Barn Swallows Hirundo rustica at an Irish reedbed during autumn migration

Barn Swallow Hirundo rustica roosting time was studied at a south‐coast Irish reedbed during 2003 to 2006. Roosting time varied between 11 and 35 minutes after sunset. There was no significant difference in roosting time after sunset across years. Roosting time (relative to sunset) was later in July than in August and September. The time interval between roosting of the earliest and latest birds usually spanned a period of about 10 to 15 minutes, but could be as long as 30 minutes. The light intensity at the time of roosting varied between 41 and 6 lux.

Mercury and organochlorine content of Dipper Cinclus cinclus eggs in south-west Ireland: trends during 1990–1999

A sample of 124 deserted/infertile dipper (Cinclus cinclus) eggs was collected in south-west Ireland during six seasons (1990-1994 and 1999) and analysed for mercury and organochlorines. Mercury was detected in three of the 6 years but no trend was observed. DDT occurred above the limit of detection in only two eggs, one each in 1993 and 1994. In contrast, two derivatives of DDT (DDE and TDE) were found much more commonly. DDE occurred in over 87% of eggs, while TDE contamination was less widespread and reached a maximum of 60% in 1993, with none detected in 1991 or 1999. There was no trend in occurrence of DDE or TDE across years. PCB contamination was present consistently over the 10-year period, with little change in the proportion of contaminated eggs collected over time. In all years, the lowest recorded occurrence of total PCBs was 69% expressed on a formulation basis as Arochlor 1254. PCB congeners 138, 153 and 180 dominated. The congener pattern was similar across years with the exception of 1990 when congener 118 dominated. A distinct trend of high values of contaminants was observed in 1990 and 1993. In 1990, PCB 118 was the dominant contaminant, while in 1993, HEOD, DDE, PCB 138 and PCB 153 were primary contributors to the observed result. Other contaminants (HCB, PCB 101, gamma-HCH, PCB 170 and PCB 180) showed little obvious patterns between years and occurred at relatively low levels. No pattern was observed in contaminants when eggs were grouped according to river or altitude. These data provide a baseline for organochlorine contamination levels in Irish freshwater ecosystems against which future trends can be assessed.

Feather lice (Mallophaga) of the Irish Dipper Cinclus cinclus hibernicus

Forty Dippers Cinclus cinclus hibernicus were caught and deloused in southwest Ireland in 2003. Two species of lice (Mallophaga) were recorded; Philopterus cincli and Myrsidea franciscoloi. Both these species are known ectoparasites of the Dipper, yet these records were the first for Ireland. The incidence and infestation rates reported in this study were significantly greater than those recorded in Dippers from two studies in Wales and Germany.

Movements of Dippers Cinclus cinclus in southwest Ireland

Totals of 1,833 nestling and 478 full grown Dippers Cinclus cinclus were ringed in southwest Ireland between 1989 and 1998. Three of these birds were reported by the public and we recaptured 373 individuals. Of these, 151 (40%) had moved from the ringing site on recapture or when found dead. Juvenile dispersal began in June. Birds ringed as nestlings moved the greatest distances (mean 6.7km) while those ringed as adults moved least. There was strong fidelity to breeding sites by adults of both sexes. Females (mean 7.47km) moved greater distances than males (mean 4.69km). Females ringed as nestlings accounted for 63.6% of movements over 5km, while only 31.2% of males ringed as nestlings travelled more than this distance. Females were more likely to cross watersheds than males. A greater proportion of birds travelled more than 5km than reported in other studies.

Breeding biology of the Grey Wagtail Motacilla cinerea in southwest Ireland

The breeding biology of Grey Wagtails in Ireland was studied over 14 years. A total of 220 nests was located, mostly on bridges. First egg dates varied from 29 March to 2 July with a peak of egg laying in the second week of April. The mean clutch size was 4.79 (± 0.04 se), the mean brood size at hatching 4.59 (± 0.05 se) and at fledging 4.00 (± 0.09 se) per successful pair. Most clutches (71%) consisted of five eggs, and these hatched and fledged more young than clutches of four. Some data on growth rates of nestlings are presented and some aspects of the breeding biology of the most westerly population of Grey Wagtails are described and compared with other studies.

Baseline and stress-induced levels of corticosterone in male and female Afrotropical and European temperate stonechats during breeding

BackgroundLatitudinal variation in avian life histories falls along a slow-fast pace of life continuum: tropical species produce small clutches, but have a high survival probability, while in temperate species the opposite pattern is found. This study investigated whether differential investment into reproduction and survival of tropical and temperate species is paralleled by differences in the secretion of the vertebrate hormone corticosterone (CORT). Depending on circulating concentrations, CORT can both act as a metabolic (low to medium levels) and a stress hormone (high levels) and, thereby, influence reproductive decisions. Baseline and stress-induced CORT was measured across sequential stages of the breeding season in males and females of closely related taxa of stonechats (Saxicola spp) from a wide distribution area. We compared stonechats from 13 sites, representing Canary Islands, European temperate and East African tropical areas. Stonechats are highly seasonal breeders at all these sites, but vary between tropical and temperate regions with regard to reproductive investment and presumably also survival.ResultsIn accordance with life-history theory, during parental stages, post-capture (baseline) CORT was overall lower in tropical than in temperate stonechats. However, during mating stages, tropical males had elevated post-capture (baseline) CORT concentrations, which did not differ from those of temperate males. Female and male mates of a pair showed correlated levels of post-capture CORT when sampled after simulated territorial intrusions. In contrast to the hypothesis that species with low reproduction and high annual survival should be more risk-sensitive, tropical stonechats had lower stress-induced CORT concentrations than temperate stonechats. We also found relatively high post-capture (baseline) and stress-induced CORT concentrations, in slow-paced Canary Islands stonechats.ConclusionsOur data support and refine the view that baseline CORT facilitates energetically demanding activities in males and females and reflects investment into reproduction. Low parental workload was associated with lower post-capture (baseline) CORT as expected for a slow pace of life in tropical species. On a finer resolution, however, this tropical-temperate contrast did not generally hold. Post-capture (baseline) CORT was higher during mating stages in particular in tropical males, possibly to support the energetic needs of mate-guarding. Counter to predictions based on life history theory, our data do not confirm the hypothesis that long-lived tropical populations have higher stress-induced CORT concentrations than short-lived temperate populations. Instead, in the predator-rich tropical environments of African stonechats, a dampened stress response during parental stages may increase survival probabilities of young. Overall our data further support an association between life history and baseline CORT, but challenge the role of stress-induced CORT as a mediator of tropical-temperate variation in life history.

Breeding biology of Barn Swallows Hirundo rustica in Counties Cork and Waterford, Ireland

Capsule Higher breeding success of Irish birds may explain why this population has not declined.