Factors affecting the feeding distribution of red-breasted geese Branta ruficollis wintering in Romania

Biological Conservation 1993, 63, 61~5

FACTORS A F F E C T I N G THE F E E D I N G DISTRIBUTION OF RED-BREASTED GEESE BRANTA R UFICOLLIS W I N T E R I N G IN R O M A N I A W i l l i a m J. S u t h e r l a n d School of Biological Sciences, University of East Anglia, Norwich, UK, NR4 7TJ

&

N i c o l a J. C r o c k f o r d Joint Nature Conservation Committee, Monkstone House, Peterborough, UK, PE1 1JY (Received 28 August 1991; revised version received 2 December 1991; accepted 16 December 1991)

Abstract During late December 1990 and early January 1991 between 23 830 and 33 830 red-breasted geese Branta ruficollis were counted in the Dobrogea region of eastern Romania, which is probably the majority of the worm population. They showed a strong preference for feeding on winter wheat. Sites where geese were observed feeding were more likely to be at lower altitude, on flatter ground, further away from human habitation, and closer to the roost than was typical of the area as a whole. The conservation of this species is discussed.

been seen in that area, apparently due to a change in agriculture from cereal and rice crops to vineyards and cotton (Grimett & Jones, 1989), although 500 were recorded in 1989 (Vinokurov, 1990). Red-breasted geese have also been recorded from the Black Sea coastlines of Russia (Eastern Manych, where 1500 winter in mild weather), Greece (0-1800) and Bulgaria (average 7600, max. 17 000) with the more southerly sites being used more in severe winters (Grimmet & Jones, 1989; Ivanov & Pomakov, 1983; Michev et al., 1981; Munteanu et al., 1991). Small numbers have been recorded in Iraq (Cramp & Simmons, 1977). The red-breasted goose was unknown in Romania before 1910 and was only occasionally seen between then and 1950, with about 20 records, mainly from the winter months (Munteanu et al., 1989). Talpeanu (1963) described it as present in Romania 'annually in tens or hundreds'. Following the decline in numbers around the Caspian Sea, a flock of 25 000 was seen near Istria in Romania in December 1968 (Johnson & Hafner, 1970) and thus it seemed that this species had shifted to a new main wintering ground. Counts in 1969-1971 in Romania were much lower: 3750 in 1969-70 (Johnson & Hafner, 1970), 4000 in December 1969 (Scott, 1970), 6000 in December 1971 (Dijksen et al., 1973), 9300 in December 1970 (Johnson & Biber, 1971) and 6000 in December 1971 (Dijksen et al., 1973). There have been few counts since 1971: c. 1000 in February 1982, 9600-12 100 in November 1982, 2400 in January 1988 and 11 630 in January 1989 (Munteanu et al., 1989). The same shift in wintering grounds was recorded in the Bulgarian part of the Dobrogea, with virtually no records before the late 1960s (Ivanov & Pomakov, 1983). The most recent estimate of the autumn world population is 35 000 from surveys in breeding grounds on the Taimyr Peninsula in the north eastern USSR (Vinokurov, 1990). Thus the recent figures from the wintering areas have been well below the current estimate from the breeding area.

INTRODUCTION The red-breasted goose Branta ruficollis has a smaller world population than any other species of goose native to Europe and is the one about which least is known. Cramp and Simmons (1977) suggested that the numbers have seriously declined and described it as being 'in urgent need of improved conservation'. Little is known of their habitat preferences or present winter distribution (Ogilvie, 1978). The population in the 1950s was estimated at about 50 000, with about 40 000 in the Kyzyl-Agach State Reserve (Russian Azerbaijan) in the winter of 1956-57 (Uspenski, 1965; Uspenski & Kishko, 1968). Subsequent estimates were lower, with 25 000 seen on the wintering grounds in 1969 (Johnson & Hafner, 1970) and 27 500 estimated in the breeding grounds during 1977-79 (Borodin, 1984). On the breeding grounds the species is thought to have been affected by excessive hunting, disturbance and habitat loss due to oil exploitation (Borodin, 1984). The Kirov Bay in the Caspian Sea used to be the major wintering area of the red-breasted goose (Dementiev & Gladkov, 1952; Vaurie, 1965), with a peak count of 40 000 being recorded in 1956 (Upenski & Kishko, 1968). Since the early 1970s only 200-250 have Biological Conservation 0006-3207/92/$05.00 © 1992 Elsevier Science Publishers Ltd, England. Printed in Great Britain 61

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W. J. Sutherland, N. J. Crockford

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As regards the species on its wintering grounds, the important questions are: Has the population declined? What is the distribution? What are the habitat requirements of this species? What conservation measures are necessary? The aims of our study were to gain an understanding of the factors affecting the distribution of red-breasted geese in the Dobrogea area of Romania, to estimate the total number wintering there and to improve our understanding of factors of conservation importance in Romania which may affect this species. To accomplish this we carried out the first systematic survey of the Romanian winter feeding grounds of red-breasted geese.

The Dobrogea is the region, flanking the Black Sea coast, which stretches from the Danube Delta in the north, down through Romania and into Bulgaria. In Romania it comprises the two counties of Tulcea and Constanta (see Fig. 1). It is an area of limestone upland flanked to the east by fertile, gently rolling coastal land. Until recently, this eastern area was predominantly steppe and used for sheep grazing. Over the last 30 years an increasing proportion has been converted to arable. Along the coast south of the Delta are a series of coastal lagoons. The peninsulas projecting into these, and particularly Grindul Chituc (Fig. 1), form safe

Red-breasted geese in Romania roost sites for large flocks of wintering white-fronted geese Anser albifrons with smaller numbers of redbreasted, greylag Anser anser, bean geese Anser fabalis and lesser white-fronted geese Anser erythropus.

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representative sample o f 183 points within the area scanned. The points were taken as the intersections of the 2-km grid squares within the area marked as scanned on the map. Areas in villages, farms or vineyards or on roads or railways were ignored as representative points.

METHODS The study took place between 29 December 1990 and 7 January 1991. Flocks of feeding red-breasted geese were searched for during a systematic coverage by car of as much as possible of the general area where the red-breasted geese are known to occur (Scott, 1970; Johnson & Biber, 1971; P. Weber, D. Munteanu & J. Marinov, pers. comm.) and other apparently suitable areas. We searched along almost all the roads in this area and many of the tracks. Some areas away from the tracks were also searched, using a four-wheel-drive vehicle, by Didier Vangeluwe and Pierre Stassin. The extent of all areas that had been scanned were marked on a 1:10 000 map as the survey proceeded (Fig. 1). The area around Sarinsasuf (20 km northeast of Enisala) was also surveyed, but we were unable to map the area scanned. Dawn and dusk counts of birds leaving and returning to the roost provided an indication of the locations of the feeding flocks. We could not accurately determine the species composition in these roost counts. We are confident of having located during the day the bulk of the geese counted during dawn and dusk flights, except for those to the north of Enisala. The position of every flock seen was marked on the map (Fig. 1) and the numbers of red-breasted geese and white-fronted geese, with which the red-breasted geese associated, were determined. Where possible birds in each flock were counted individually, otherwise the number of birds in each flock was estimated by counting groups o f 10, 50 or 100 individuals and then counting the number of groups of that size in the total flock. Two different methods were used to determine the site choice by the geese. (A) The habitat of the area was assessed whilst driving along the roads and tracks and a dictaphone used to record the land use on either side of the route at 1-km intervals. The land was classified into the following categories: winter wheat, maize stubble, plough, steppe, fallow, vines, beet and trees. Areas with buildings or farms were ignored. (B) From the map, the following measurements were made from the estimated position on the map of the centre o f each feeding flock: altitude slope (derived from the distance between contours), aspect, distance to roost (for the point taken as position o f roost see Fig. 1), distance to edge o f nearest farm or town, distance to nearest road (which carried little traffic). The parameters of these points at which we had observed geese feeding were compared with those from a regular

RESULTS Thirty-four red-breasted goose feeding sites were located (Fig 1). During our short survey period these were separable into the five main groups, on the basis that similar-sized flocks were repeatedly seen at sites in the same area. The largest flock of red-breasted geese seen in each area was: (a) southeast of Mihail Kagalniceanu, 600; (b) Istria/ Sacele/Nuntasi, 10 000; (c) Mihail Viteazu, Rimnicu de Jos and Cogealac, 17 000; (d) Visina, 5 550; (e) Sarinasuf, 680 (not marked on the map - - 20 km northeast of Enisala. A single flock was seen on the only occasion this area was visited). This gives a total of 33 830 birds. There may be some overlap between the birds seen at (b) and (c). In the extreme but unlikely case of all the birds at (b) also being counted at (c) the total population is then estimated at 23 830. The habitat of each feeding flock was determined from amongst the categories listed in method (A) above. Some flocks were feeding on more than one land use type; for this analysis they were counted as separate observations. O f the total 38 feeding sites, 33 (86-8%) were on winter wheat, four on maize stubble (10-5%) and one on plough (2.6%). Of the 363 habitat samples taken (using method (A) above) the number of registrations of each different land use were: winter wheat, 136 (37.3%); plough, 121 (33.2%); maize stubble, 39 (10.7%); steppe, 36 (9.8%); fallow, 14 (3.8%); vine, 10 (2.7%); beet, 4 (1.0%; and trees, 3 (0.8%). The red-breasted goose feeding preference for winter wheat as compared with other habitats is highly significant (G = 18.1, p < 0.001). Red-breasted geese have been recorded feeding on the remnant steppe pasture near the coast (P. Weber, pers. comm.). Figure 2 shows the parameters of the sites used by the geese in comparison with those from the representative sample of points taken throughout the area scanned (method (B) above). This showed that, although some flocks occurred at higher sites (over 100 m), they showed a significant tendency to select the sites at lower altitude (representative height = 101.2 + 48.0 m, geese = 76.97 + 55.21 m, t = 2-60, p < 0.01). They also significantly selected the flatter sites (representative slope expressed as distance between 10-m contours) -- 0-53 + 0.40 km, geese = 0-72 + 0.50 km, t = 2.34, p < 0.02). They showed no significant preference for any aspect (representative aspect = 158.7 °, geese = 116-0°, /71,204 = 0.97; Watson-Williams test (Batschelet, 1981)). They selected sites closer to the roost than the representative points (representative = 26-6 + 9-31 km, geese -- 20.0 + 8.54 km, t = 3-78, p < 0.001) and no birds were further than 40 km from it.

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W. J. Sutherland, N. J. Crockford (b) Slope

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Fig. 2. Features of the red-breasted goose feeding sites (below) compared with representative points (above) from the area scanned (a) altitude; (b) slope expressed as the distance between 10-m contours; (c) distance to habitation; (d) distance to roost. The geese avoided areas close to farms/towns (representative -- 1.70 + 0.93 km, geese = 2-06 + 0.78 km, t = 2.08, p < 0.05). Although on average they occurred further away from roads this trend was not significant (representative = 1.53, geese = 1.62, t = 0-42, NS). DISCUSSION The Dobrogea region of Romania is now of exceptional importance for red-breasted geese. The most recent total population estimate for this species is 35 000 from autumn counts on the breeding grounds (Vinokurov, 1990). Therefore, with counts of between

23 830 and 33 830, and assuming that our survey must have missed some birds, particularly in the north, the majority of the world population may have been present in the study area during the period o f the study. As described in the introduction, only small numbers have been recorded wintering in other countries, including the USSR and Bulgaria, since the late 1960s. There is a clear need for coordinated counts throughout the range and for some cooperation on flyway management. At present the habitat available in the Dobrogea appears to be ideal for red-breasted geese. They have fairly well-protected roost sites, freshwater lagoons for

Red-breasted geese in Romania

drinking and bathing to which they fly periodically during the day as well as using them at dawn and dusk, large open expanses of winter wheat and little disturbance. The main roost on the northern tip of Grindul Chituc is relatively inaccessible and, as it lies in a coastal border zone, is protected by the military. There is a risk that it may become more accessible as the border is becoming less strictly guarded. However, it is now part of the Danube Delta Biosphere Reserve and Ramsar site, which should facilitate a continuation and consolidation of the strongest possible protection. Some goose shooting is undertaken, at present only by local hunters, especially on the pre- and post-roost sites but also on the feeding areas, drinking areas and occasionally illegally at the roost site. This is unlikely to affect the red-breasted goose population directly, especially as they are not a preferred quarry species and the presence of over a hundred thousand white-fronted geese will dilute the probability of red-breasted geese being shot. We saw only one goose shot (a juvenile lesser white-front). Probably more important is the disturbance caused by shooting. During our 13 roost counts we witnessed five instances of shooting. The amount of shooting in the area needs to be closely monitored and perhaps regulated. The development of hunting tourism from other countries or Romanian regions would be cause for considerable concern. The international importance of this area for redbreasted geese is dependent upon current agricultural policies, especially any affecting the extent of winter wheat in the Dobrogea. Following the revolution in December 1989 changes in agricultural practice in Romania are likely. Any measures to subdivide the feeding area structurally, abandon or otherwise change its agricultural use would be likely to have a detrimental impact on the red-breasted goose population. The present work provides a framework for a description of the most important areas to maintain. It is to be hoped that with the current progressive attitude towards conservation in Romania the required agricultural reforms can be carried out in a way which maintains suitable feeding habitat for this species. ACKNOWLEDGEMENTS This work would not have been possible without the assistance of Dr Dan Munteanu and the Romanian Ornithological Society. We thank Didier Vangeluwe and Pierre Stassin for providing us with details of their counts. Mikai Marinov and Peter Weber shared with us their considerable experience of their area and this species. We thank Dr Gomoiu and the Munteanu family for their hospitality. Dr Zbig Karpowicz, IUCN and Minister Vadineanu helped make this work

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possible. Hugh Boyd, Jennifer Gill, Dan Munteanu and David Stroud made useful alterations to the manuscript. Tony Fox made invaluable comments. Diane Alden drew the figures. The British Ecological Society funded W. J. S. REFERENCES Batschelet, E. (1981). Circular Statistics in Biology. Academic Press, London. Borodin, A. M. (ed.) (1984). The Red Data Book of the USSR: Rare and Endangered Species of Animals and Plants. Vol. 1, Animals, 2nd edn. Promyshlennost, Moscow. Cramp, S. & Simmons, K. E. L. (eds) (1977). The Birds of the Western Palearctic, Vol. 1. Clarendon Press, Oxford. Dementiev, G. P. & Gladkov, N. A. (1952). The Birds of the Soviet Union, Vol. 4. Moscow. Israel Program for Scientific Translations, Jerusalem. Dijksen, A. J., Lebret, T., Ouweneel, G. L. & Philippona, J. (1973). Ornithological observations on the lagoons of the Dobrogea, Rumania, in autumn and winter of 1969, 1970 and 1971. Ardea, 61, 159-78. Grimmet, R. F. A. & Jones, T. A. (1989). Important Bird Areas in Europe. International Council for Bird Preservation, Cambridge. Holloway, C. W. (1970). Proceedings of the Conference on Productivity and Conservation in Northern Circumpolar Lands, Edmonton, ed. W. A. Fuller & P. G. Kevan. IUCN Pubis New Series, 16, 175-92. Ivanov, B. E. & Pomakov, V. A. (1983). Wintering of the red-breasted goose (Branta ruficollis). Aquila, 90, 29-34. Johnson, A. & Hafner, H. (1970). Winter wildfowl counts in south-east Europe and western Turkey. Wildfowl, 21, 22 36. Johnson, A. R. & Biber, O. (1971). IWRB goose-working group mission to Eastern Europe December 1970. Station Biologique de la Tour du Valet, Aries (unpublished report). Michev, T. M., Nantinov, D. N., Ivanov, B. E. & Pomakov, V. A. (1981). Midwinter numbers of wild geese in Bulgaria. Aquila, 90, 45-52. Munteanu, D., Toniuc, N., Weber, P., Szab6, J. & Marinov, M. (1989). Evaluarea efectivelor pasarilor acvatice in cartierele lor de iernare din Romgmia (1988, 1989). Ocrot. nat. reed. inconj., 33, 105 12. Munteanu, D., Weber, P., Szab6, J., Gogu-Bogdan & Maroniv, M. (1991). A note on the present status of geese in Romania. Ardea, 79, 165-6. Ogilvie, M. A. (1978). Wild Geese. T & A. D. Poyser, Berkhamsted. Scott, P. (1970) Redbreasts in Romania. Wildfowl, 21, 37-41. Talpeanu, M. (1963). Anseriformes of Romania. In Proc. Eur. Mtg on Wildfowl Conservation, 1st St. Andrews, Scotland, pp. 45-9. Uspenski, S. M. (1965). Die Wildganse Nordeuasiens. Neue Brehm-Bucheri, Wittenburg. Uspenski, S. M. & Kishko, Yu. I. (1968). Winter range of the red-breasted goose in the Easter Azerbaidzhan. Problemy Severa, 11, 235-43. Vaurie, C. (1965). The Birds of the Palearctic Fauna, NonPasseriformes. Witherby, London. Vinokurov, A. A. (1990). Branta ruficollis in the USSR. In Managing waterfowl populations. Proc. IWRB Syrup., Astrakhan 1989, ed. G. V. T. Matthews. IWRB Spec. Pubis, No. 12, Slimbridge, pp. 197-8.