EURING SWALLOW PROJECT

THE EURING SWALLOW PROJECT IN FINLAND
YEARS 1999 - 2000

by Pertti Saurola

RINGING CENTRE
FINNISH MUSEUM OF NATURAL HISTORY
P.O.BOX 17
FIN-00014 UNIVERSITY OF HELSINKI
Email: pertti.saurola@helsinki.fi

RESEARCH ACTIVITIES IN 1999

In total, 24,134 Barn Swallows Hirundo rustica were ringed in Finland in 1999 by 138 ringers. This was again a new record (64% more than in 1997) and consisted of 8642 nestlings, 987 breeding adults and 14 449 full-grown birds roosting in reed-beds; all these three figures were new annual records. The number of ringings was distributed unevenly across the 10x10 km squares of the Finnish National Grid, and also the ringing effort was distributed unevenly among the ringers: 59% of nestlings were ringed by three ringers, 64% of adults captured at the nest were caught by three ringers, and 59% of swallows ringed at the reed-beds were caught at four sites.

Hatching dates in 1999 were estimated of all broods ringed in "Häme" (= Hauho, 61o10'N /24o35'E, and surrounding communes) and in "Savo" (= Pielavesi, 63o15'N /26o 45'E, and surrounding communes) on the basis of the wing length of the oldest young of the brood (cf. Saurola 1999). In 1999 breeding started about a week earlier than in 1998.

A total of 16 hybrids between the Barn Swallow and House Martin, Delichon urbica, belonging to 10 different broods were detected already as nestlings. In Savo one out of 128 Swallow nestlings was a hybrid! In all these cases the nests were located inside the building and no House Martins were seen close to the nests. In addition, 26 hybrids were captured in 1998 as first year birds in 8 reed-beds. This means that one out of 489 Swallows ringed at roosts was a hybrid. Altogether 80 such hybrids have been reported from Finland so far.

In total, 1,347 breeding adults were captured, either ringed or recaptured, at the nest in Finland in 1999. Of all 363 adults recaptured at the nest in 1999, 265 (73%) were originally ringed as breeding adults, 72 (20%) as nestlings and 26 (7%) as roosting birds in the reed-beds in 1998 or earlier. In 1998, 908 adults were captured at the nest. Out of these 239 (26%) were recaptured at the nest in 1999 as well. The distances moved between the successive nest sites by these adults of 1998 were: 232 x 0 km, 5 x 1 km, 1 x 2 km and 1x 18 km. Hence, the fidelity to the nest site was extremely high.

The data on natal dispersal has not yet been corrected with the geographical distribution of the effort of ringing the nestlings and of catching the adults at the nest. According to the uncorrected data (n= 95), 17% of young swallows returned to their natal colony, 73% moved less than 6km, 86% moved less than 10 km and all moved less than 28 km from their natal colony.

Ringing of Swallows roosting in reed-beds in August-September was carried out at 30 sites by 28 ringers during 340 sessions in total. However, only at 18 of the sites over 100 birds were ringed. Catching at roosts in Häme was difficult in 1999 because the Swallows were not strictly linked to the roost. In 1997 and 1998, roosting Swallows were caught at Lusinselkä and Pyhäjärvi. In 1999, very few Swallows were roosting at these sites. A new roost, Roinelahti was detected 30 July with a good number of birds. The numbers of Swallows roosting were high from 31 July to 24 August and numbers decreased dramatically afterwards. New roosts were searched actively, and a next one was not found on 28 July, when a huge number of Swallows was found in Väinölänlahti. However, this roost was already abandoned on 29 July, before catching had started! The next roost Ali-Äijälä was detected 1 September and was very good in numbers to 9 September. After that, a small number of roosting Swallows were caught at a roost found near Muttamo. Why did the Swallows abandon their roosts? First of all, in Häme, there is a huge amount of good habitat available for roosting Swallows. They can easily find a new one if they want to change. Disturbance made by ringing and/or disturbance made by hunting Hobbies Falco subbuteo could be the main causes to abandon the roost. In any case, at these sites ringing was carried out very carefully with the minimum amount of disturbance.

I have tried to get some preliminary information for the following question. What is the probability that a nestling born at a given distance from a given roost will be recaptured at that roost? The results suggest that the recapture probability of a Swallow ringed 0-5 km from the roost is twice as high as the recapture probability of Swallows ringed 10-15 km from the roost, etc.

As for new data on migratory routes folowed by Finnish swallows, an exceptionally strong migration of Barn Swallows through the Ornithological Station Ventes Ragas in Lithuania was observed between 6 September and 17 September 1999 (Patapavicius pers. comm.). During that period 10,155 Swallows were ringed and 10 birds from Finland were controlled. These were the first Lithuanian recaptures/recoveries of Finnish Swallows ever. In 1999, 8 new recoveries were reported from Africa.

RESEARCH ACTIVITIES IN 2000

In the year 2000, a total of 25,007 Barn Swallows Hirundo rustica were ringed in Finland. This was again a new record, with 8,446 nestlings, 1,139 breeding adults and 15,417 full-grown birds roosting in reed-beds.

Few ringers were able to contribute a large proportion of the data; 52% of the nestlings were ringed by two ringers, 42% of the adults captured at the nest were caught by one ringer, and 55% of the Barn Swallows ringed at the reed-beds were caught at five sites.

Hatching dates in 2000 were estimated of all broods ringed in "Häme" (= Hauho, 61o10'N /24o35'E, and surrounding communes) and in "Savo" (= Pielavesi, 63o15'N /26o 45'E, and surrounding communes) on the basis of the wing length of the oldest young of the brood. Breeding started in Häme four days and in Savo six days later in 2000 than in 1999. This difference can be attributed to the cold period in early summer (cf. Haapala et al. 2001).

In 2000, eight hybrids between the Barn Swallow and House Martin, Delichon urbica, belonging to 7 different broods were detected as nestlings. In addition, 20 hybrids were captured in 2000 as first year birds in reed-beds (cf. Saurola 2000).

In total, 1,594 breeding adults were captured, either ringed or recaptured, at the nest in Finland. The first estimate of the annual survival of adult Finnish Barn Swallows was based on the capture-recapture modelling with the program MARK and on data from Hauho, where breeding adults were captured every year since 1997. The estimate 0.49 (95% confidence limits 0.42-0.56) was clearly higher than the ones given by Siriwardena et al. (1998) and Moller & Lope (1999).

The ringing of Barn Swallows roosting in reed-beds in August-September was carried out at 29 sites by 34 ringers during a total of 312 sessions. However, only 21 sites ringed over 100 birds. The average body mass of first-year Barn Swallows ringed in reed-beds was 18.5 g in the beginning of August, 19.3 g in the middle of August and 20,9 g during the first 10-day period in September. At the beginning of September the young Swallows were as heavy as at the same time in 1998, but heavier than in 1999.

New data have been gathered on movements and routes followed by Finnish Swallows. In total, 74 Barn Swallows ringed in Finland have been reported from abroad: 34 were recaptured, 14 killed and 26 were found dead. The EURING Swallow Project has produced 30 new foreign recoveries of Swallows ringed in Finland. Of all foreign recoveries, 30 are from southern Africa, 12 from equatorial Africa, 9 from Mediterranean countries and 23 from Baltic countries.

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