Náttúrufræðingurinn

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Náttúrufræðingurinn - 1995, Side 102

Náttúrufræðingurinn - 1995, Side 102
range size, brood movements and habitat se- lection. Ornis Scandinavica 16. 181-190. Ferguson, R.S. 1991. Detection and classifica- tion of Muskox habitat on Banks Island, Northwest Territories, Canada, using Land- sat Thematic Mapper data. Arctic 44, Supp. 1. 66-74. Finnur Guðmundsson 1960. Some reflections on ptarmigan cycles in Iceland. Proceedings of the Xllth International Ornithological Congress, Helsinki 1958. 259-265. Hill, M.O. 1979a. DECORANA - a fortran pro- gram for detrended correspondence analysis and reciprocal averaging. Section of ecology and systematics, Comell University, Ithaca, New York. 52 bls. Hill, M.O. 1979b. TWINSPAN - a fortran pro- gram for arranging multivariate data in an ordered two-way table by classification of the individuals and attributes. Section of ecology and systematics, Cornell Univer- sity, Ithaca, New York. 90 bls. Hudson, P.J. 1986. Red Grouse: the biology and management of a wild gamebird. The Game Conservancy Trust, Fordinbridge. Hörður Kristinsson 1986. Plöntuhandbókin. Örn og Örlygur, Reykjavík. 304 bls. Hörður Kristinsson & Helgi Hallgrímsson 1991. Gróður í Mývatnssveit. í Náttúra Mý- vatns (ritstj. Arnþór Garðarsson & Arni Ein- arsson). Hið íslenska náttúrufræðifélag. Bls. 237-255. Jenkins, D., A. Watson & G.R. Miller 1967. Population fluctuations in the Red Grouse Lagopus lagopus scoticus. Journal of Ani- mal Ecology 36. 97-122. Laake, J.L., S.T. Buckland, D.R. Anderson & K.P. Bumham 1991. Distance sampling: abundance estimation of biological populat- ions, distance user guide. Fjölrit. 53 bls. Miller, G.R., D. Jenkins & A. Watson 1966. Heather performance and Red Grouse populations. I. Visual estimates of heather performance. Journal of Applied Ecology 3. 313-326. Miller, G.R., A. Watson & D. Jenkins 1970. Responses of Red Grouse populations to ex- perimental improvement of their food. I Animal populations in relation to their food resources (ritstj. A. Watson). Blackwell Sci- entific Publication, Oxford. Symposia of the British Ecological Society 10. 323-334. Ólafur K. Nielsen 1995. Rjúpnatalningar á Norðausturlandi 1981-1994. Náttúrufræð- ingurinn 65. árg, til birtingar. Palmeirim, J.M. 1988. Automatic mapping of avian species habitat using satellite im- agery. Oikos 52. 59-68. Pearce, C.M. 1991. Mapping Muskox habitat in the Canadian High Arctic with SPOT sat- ellite data. Arctic 44, Supp. 1. 49-57. Rands, M.R.W. 1986. The survival of game- bird (Galliformes) chicks in relation to pes- ticide use on cereals. Ibis 128. 57-64. Sokal, R.R. & F.J. Rohlf 1981. Biometry. W.H. Freeman & Co, San Francisco. 859 bls. Steindór Steindórsson 1964. Gróður á íslandi. Almenna bókafélagið, Reykjavík. 186 bls. Steindór Steindórsson 1974. Skrá um íslenzk gróðurhverfi. Rannsóknarstofnunin Neðri Ás, skýrsla 17. 1-23. Steindór Steindórsson 1980. Flokkun gróðurs í gróðurfélög. Islenskar Landbúnaðarrann- sóknir 12. 11-52. Timmermann, G. 1949. Die Vögel Islands. Vísindafélag fslendinga 28. 241-524. Wallin, D.O., C.C.H. Elliott, H.H. Shugart, C.J. Tucker & F. Wilhelmi 1992. Satellite remote sensing of breeding habitat for an African weaver-bird. Landscape Ecology 7. 87-99. ■ SUMMARY Rock Ptarmigan Density AND HEATHLAND VEGETATION in Suður-Þingeyjarsýsla, NE-Iceland The purpose of this paper is to analyse the re- lationship between breeding density of Rock Ptarmigan (Lagopus mutus) and different types of heathland vegetation. The study area was in NE-lceland (Fig. 1). This is an area of extensive rolling heathlands. The Icelandic ptarmigan population has a 10-year cycle (Finnur Guðmundsson 1960) and 1993, the study year, was a low year. Differences in spring density between high and low years on study plots in NE-Iceland have been c. 6-fold. Differences in spring density between differ- ent census plots within the same year have been c. 8-fold (Ólafur K. Nielsen 1995). The count point sites were placed in 7 main heathland areas so as to cover a gradient from the coast and 50 km inland. Within these areas a total of 42 count sites were chosen using a map (1:50.000) and a grid with points placed by using a random function. The only prereq- uisites were that the count sites should be 100
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