EURING Newsletter - Volume 3 - July 2001

EURING SWALLOW PROJECT

THIRD NEWSLETTER YEARS 1999 - 2000

by Fernando Spina

ISTITUTO NAZIONALE PER LA FAUNA SELVATICA
VIA CA' FORNACETTA 9 - I-40064 OZZANO EMILIA (BO), ITALY
E-mail: infsmigr@iperpole.bologna.it

This newsletter reports the results gathered by the EURING Swallow Project (ESP) during both 1999 and 2000; the reason for having 'missed' the 1999 annual newsletter lies in the difficulties in getting the summary data from the schemes, as well as to problems in data management by the co-ordination in Bologna.

Geographical coverage 1999-2000: a total of 12 countries joined the project in 1999 (Tab. 1), while 15 countries were active in 2000 (Tab. 2). Two important additions to the project came in 1999, when Denmark joined for the first time, and 2000, when France had the start of ringing activities, after having already carried out an important national swallow project over 10 years ago. The geographical coverage of the ESP in these last two years is reported in Figs. 1,2. Since the pilot year of 1997, a total of 25 countries took part into the project (Tab. 3), offering a very good coverage across Europe (Fig. 3).

A special report on the activities during 1999-2000 in Finland is offered by Pertti Saurola (see below).

Overall, 7 countries (Finland, Germany, The Netherlands, Italy, Slovenia, Spain, Switzerland) joined the project so far.

During the four years, many more birds were ringed at roosts, which offer the potential for high trapping figures, but large samples originate also from the colonies (Fig. 4). Overall, more than 500,000 swallows have been ringed since the start of the project.

As for the activities in other continents, in South Africa a number of roosts were studied, and regular ringing activities were continued by Rick Nuttall in the well known tree roost in Bloemfontein (see below). In the United States a number of banders were marking breeding swallows in 2000, given the most interesting absence of roosting behaviour in North American Barn Swallows, and we hope to get summary data soon. A strong interest for the project asshown by the Japanese Ringing Scheme, on the basis of the intense research activities already carried on both on pre-migratory roosting swallows in Japan, and on the wintering grounds in peninsular S.E. Asia and Sunda islands (see below). A joint Japanese-Italian expedition to study some of the main winter roosts of Asian Barn Swallows in Borneo was organised in Sabah in January 2001, on the kind invitation of Dr. Kiyoaki Ozaki, from the Japanese ringing sheme at the Jamashina Institute of Ornithology.

Tab. 1 - Ringing totals 1999.

Tab. 2 - Ringing totals 2000.

Tab. 3 - Active countries 1997-2000.

Fig. 1 - Geographical coverage year 1999

Fig. 2 - Geographical coverage year 2000

Fig. 3 -Geographical coverage years 1997 - 2000

Fig. 4

Data analysis

The coordination of the migration section of the EURING swallow project at the Bologna Ringing Scheme has analysed data collected at roosts in different European countries to investigate relationships between pre-migratory strategies and the eco-geographic features of the routes followed by swallows on autumn migration.

Dr. Diego Rubolini carried on these analyses for his thesis, taking into account data from Finalnd, Lithuania, UK, Germany, Switzerland, Italy, Spain and Malta. He was able to confirm preliminary results obtained from the pilot year of the project (Pilastro & Spina 1999, see EURING newsletter 2). Swallows seem to accumulate fat while approaching the ecological barriers (Mediterranean Sea and Sahara desert) they will have to overcome in order to reach the African wintering grounds. Birds leave northern latitudes in Europe (e.g. Finland) without significant fat depots, getting progressively fatter at lower latitudes. Differently from what often reported, swallows do not seem to adopt a "fly-and-forage" strategy, but rather accumulate fat as other long-distance songbird migrants do, up to 40-60% of lean body mass just before barrier crossing.

More detailed analyses were performed to better investigate the relationships between ecological barriers and swallow migration across Europe (Rubolini et al., J. Avian Biol., in press). When taking into account pre-migratory conditions of swallows ringed in southern Spain vs. southern Italy, a significant positive correlation was found between the extension of ecological barriers and the amount of energy stores. The barriers were expressed as distance from the different roosts to the coast of North Africa, as well as to the southern edge of the Sahara. The weaker correlations obtained when considering only the Mediterranean as a barrier indicates that swallows may cross the desert without substantial refuelling in North Africa. Hence, departure conditions from southern Europe suggest a fast migration across the barriers.

The observed differences in fuel stores between Italian and Iberian Barn Swallows suggest a degree of population-specific variability, and the extension of ecological barriers may play a role in determining the amount of stores needed for the migratory flight.

These very interesting results confirm the great potential of our Swallow project in unravelling still undescribed migratory patterns even in one of the reportedly best known migrants. It is now important to further improve the geographical coverage of the project, and especially to collect more data from central-eastern Europe, in order to describe another most important route, funnelling along the eastern Mediterranean and the Nile.

Analyses in Italy

The strong involvement of Italian ringers in the project provided a very good seasonal and geographical coverage of roosts, and a large set of data to analyse. In the last two years, Lara Marangoni, Alessandra Stagni and Fernando Spina analysed features of the swallow pre-migratory phase in Italy, by taking into account possible differences between sex- and age-classes, as well as along the latitudinal gradient. A huge sample of over 160,000 swallows was used.

In the pre-migratory phase swallows are leaner in the north of Italy and fatter further south; this difference disappears when analysing adults in the last phase before departure, when conditions do not differ between the two areas. Adults leave the northern roosts earlier and in better conditions than juveniles, suggesting a higher foraging efficiency.

The roosts are used already since June, mainly by juveniles and by adult males (these might also belong to the non-breeding part of the higher fraction of males within the sexes, A. Møller, in verbis). In the early stages of the roosts, juveniles have better conditions than adults, and males are in better conditions than females. The difference between sexes disappears later in the season; adults are finally leaving the roosts with higher energy stores than juveniles.

The very large set of data collected in Italy produced an interesting sample of nearly 500 controls between colonies and roosts, as well as among roosts. These data were used by Davide Licheri to investigate the seasonal patterns of movements across Italy. He found that swallows move towards the north on post-fledging movements (July-August), while later in the season (September- October) the larger movements recorded are mainly directed towards the migratory direction of south. Northwards movements are performed in birds younger than 70 days of age; these movements can be meant to build up a navigational target for the birds. The accumulation of fat is seasonally controlled, as the same patterns of increase are recorded in first year birds during the pre-migratory phase, regardless of their age.

All these results are being arranged in a series of papers which we hope will contribute to the better understanding of the pre-migratory behaviour of swallows in Italy, a country which really seems to bridge swallows to the south, before the risky phase of their journey across the vast barriers towards Africa.

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