|Nutritional and genetic adaptation of galliform birds: implications for hand-rearing and restocking|
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The grey partridge is divided into eight subspecies, based mainly on the plumage colour (VI, Table 1, after Potts 1986): P. p. hispaniensis, P. p. italica, P. p. armoricana, P. p. sphagnetorum, P. p. perdix, P. p. lucida, P. p. canescens, and P. p. robusta. The existence of additional three subspecies P. p. belesiae, P. p. galliae (France) and P. p. hilgerti (Germany) is discussed (Birkan & Jacob 1988). The species has its origin in steppes, but has taken advantage of cultivated farmland in the temperate zone. Its distributional range covers most of Europe, Asia Minor, and Caucasus from the northern parts of the Caspian Sea to Central Asia. In Europe its distribution covers the continent excluding Iceland and the northernmost parts of Fennoscandia and Russia (Potts 1986).
In Finland, the grey partridge lives at its northernmost distribution range, the northern border of which crosses Finland from the Oulu region to the southeastern part of the country (Väisänen et al. 1998). Its highest numbers can be found in South Ostrobothnia, where in the winter of 1999/00 about 9 200 birds were counted (J. Bisi, pers. comm.). In Finland, the grey partridge is classified as a near-threatened species (Rassi 2000).
The grey partridge is believed to have arrived in Finland in the beginning of the 1800’s from the east via the Karelian isthmus (Kivirikko 1948), but entry may have occurred as early as in 1690 (Merikallio 1958). The first introduced birds in 1750 (Merikallio 1958) were probably of Swedish origin. According to early Finnish ornithological literature and handbooks, and categorisation by morphological characteristics, the Finnish population represents subspecies P. p. lucida, while the nominate P. p. perdix is a more southern and western subspecies (Westerskov 1964, Cramp & Simmons 1980, Potts 1986).
The number of the grey partridges in Finland has dramatically decreased during past decades. In the 1950’s the population size was estimated to be 15 000 pairs (Merikallio 1958), but in the early 1990’s there were only 4 000 pairs (Koskimies 1992). The population decline in the whole distributional area is estimated to be about 80 % since the 1950’s. Additionally, the distribution area has become patchy (Potts 1986).
The worldwide decline in the numbers of the grey partridge is extremely well documented (for review, see Potts 1986). The main reason for the worldwide population crash is considered to be the changes in agriculture practices (Rands 1985, Potts 1980, 1986, Fog 1988, Matteucci 1988, Olech 1988, Panek 1992). The grey partridge uses open ditch banks to find cover and nesting sites, as well as plant material for adults and invertebrates for chicks (Pulliainen 1965, Potts 1986, Panek 1992, Sotherton 1992). Adult birds feed mainly on weed seeds (hemp-nettle Galeopsis spp., pale persicaria Persicaria lapathifolia, knotgrass Polygonum aviculare, black-bindweed Fallopia convolvulus, fat-hen Chenopodium album), grains, and shoots (oats Avena sativa, barley Hordeum vulgare, rye Secale cereale, wheat Triticum aestivum) (Potts 1970, Pulliainen 1965, 1984). Chicks feed on a variety of invertebrates (Ford et al. 1938, Potts 1986, Itämies et al. 1996); most preferred are leaf-hoppers (Delphacidae) and beetles (Coleoptera) (Itämies et al. 1996). Intensive farming with large monotonous, subsurface drained fields, hard machinery and use of pesticides have reduced the survival and breeding success of the grey partridge (Potts 1980, 1986, Panek 1992, Sotherton 1992) by reducing the quantity and diversity of invertebrates. Indirectly, the use of pesticides has reduced the quality and quantity of weeds, which in turn has decreased the numbers of invertebrates feeding on these plants (Potts 1986, Panek 1992, Sotherton 1992). In addition to this modern farming has changed the habitat more unsuitable for partridges – and to some extent more suitable for predators (Potts 1986).
The capercaillie breeds in Eurasian coniferous taiga forests from Scandinavia to Central Siberia (Cramp & Simmons 1980). In Finland it is absent only in the northernmost parts of the country. Its distribution follows the distribution of the Scots pine Pinus sylvestris, from the southern coast to Kittilä and Inari. The lowest densities can be found in the Åland Islands, on the archipelago, and in Southern Lapland. The highest densities are found in Ostrobothnia and in Kainuu near lake Oulujärvi (Väisänen et al. 1998). The population size of the capercaillie in Finland is about 750 000 adult birds (Lindén 1996).
The capercaillie is often taken as an indicator for old and mature forests (Storch 1993, but see Helle & Helle 1991, Picozzi et al. 1992), preferring mature spruce Picea abies or pine forests, mires or bogs. It also prefers mixed to monotypic forests. The optimal area is mosaic-like diverse, providing the capercaillie with proper environment throughout the year (Helle et al. 1990, 1994, but see Helle & Helle 1991). The diet of the capercaillie consists almost entirely of berries and leaves of cowberry Vaccinium vitis-idaea, bog bilberry V. uliginosum, bilberry V. myrtillus, crowberry Empetrum nigrum and cloudberry Rubus chamaemorus in the autumn. In September, it starts to feed on pine needles, and becomes monophagous by December (Pulliainen 1978, 1981). Mostly browsed pines are often injured by fire (Lindroth & Lindgren 1950). Chicks feed mainly on invertebrates (Rajala 1959, Picozzi et al. 1999), and young birds may feed on insects in the autumn, although their proportion of the diet is only about 0.1–0.3 % (Pulliainen 1979).
The declining number of capercaillie is a general phenomenon in Europe (Angelstam & Sandegren 1981, Rolstad & Wegge 1989, Helle & Helle 1991, Schroth 1991). The population in Finland has decreased by about 70 % during the last three decades and the distribution area has become patchy. The main reason for this decline is considered to be forest fragmentation, and decreasing number of large old-growth forests (Lindén & Rajala 1981, Lindén & Pasanen 1987, Storch 1991, Lindén et al. 2000). Effective predation (Helle et al. 1999), and also effective hunting of adult birds, especially hens, may have severely influenced the population size (Lindén 1981).