Population Trends for Swedish Breeding Birds Populationstrender För Fåglar Som Häckar I Sverige
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ORNIS SVECICA 19: 117–192, 2009 https://doi.org/10.34080/os.v19.22652 Population trends for Swedish breeding birds Populationstrender för fåglar som häckar i Sverige RICHARD OTTVALL, LARS EDENIUS, JOHAN ELMBERG, HENRI ENGSTRÖM, MARTIN GREEN, NIKLAS HOLMQVIST, ÅKE LINDSTRÖM, TOMAS PÄRT & MARTIN TJERNBERG Abstract We have assessed the population trends for the 255 bird Richard Ottvall, Martin Green and Åke Lindström, De- species breeding in Sweden (including distinct subspe- partment of Ecology, Lund University, Ecology Building, cies), based on data for the last 30 and 10 years, respec- SE-223 62 Lund, Sweden. tively. Over the past 30 years more species have decreased Lars Edenius, Department of Wildlife, Fish and Environ- (38%) than increased (32%) in numbers. In particular, mental Studies, Swedish University of Agricultural Sci- formerly common farmland species have fared poorly ences, SE-901 83 Umeå, Sweden. but this is also true for some forest species. Over the past Johan Elmberg, Aquatic Biology and Chemistry, Kris- 10 years there are more species with increasing trends tianstad University College, SE-291 88 (29%) than there are species with decreasing trends Kristianstad, Sweden. (19%). Trends for several species in long-term decline Henri Engström, Department of Ecology and Evolution, have levelled off and have in some cases even started to Uppsala University, Norbyvägen 18D, SE-752 36 Upp- increase. It is not known whether this recent change is a sala, and Swedish Ornithological Society, Ekhagsvägen result of conservation efforts or simply that population 3, SE-104 05 Stockholm, Sweden. numbers have stabilised at lower levels now permitted by Niklas Holmqvist, Swedish Association for Hunting the environment. It is therefore essential to initiate re- and Wildlife Management, Öster Malma, SE-611 91 search devoted to finding factors directly linked to ongo- Nyköping, Sweden ing population changes, particularly for species in long- Martin Tjernberg, Species Information Centre, Swedish term decline. To cover population trends for all Swedish University of Agricultural Sciences, PO Box 7007, SE- species additional monitoring programmes are needed, in 750 07 Uppsala, Sweden. particular on owls and in mountain habitats. Tomas Pärt, Department of Ecology, Swedish University of Agricultural Sciences, PO Box 7044, SE-750 07 Upp- sala, Sweden. Received 18 February 2009, Accepted 20 February 2009, Editor: S. Svensson food chain and so may be sensitive to the status of Introduction other organisms at lower levels in food webs. Birds Biodiversity has been on the international political are found in all our ecosystems and they are rela- agenda for some time. The UN has adopted an im- tively easy to study and identify by their appear- portant goal, that is, to clearly reduce the loss of bi- ance, song or call. They are also fairly well known odiversity by 2010 at the latest. The same goal was to the general public and decision makers, and also adopted by the EU member states in Gothen- often possess symbolic value in relation to nature burg in 2001. For Sweden’s part, the goal has been conservation. expressed as: "the loss of biodiversity should have Bird population trends have been one of the EU's been halted by 2010 at the latest". official environmental indicators for some years We know that biodiversity is declining in Swe- (Gregory et al. 2005). These indicators show quite den, but there is no quantitative information on the clearly that European farmland birds (particularly trends for many species. In many ways birds are in Western Europe) are doing badly, but that many suitable indicators of the state of the environment, forest species have also declined drastically in re- since they are better known and have been studied cent decades (Gregory et al. 2005, 2007). Since in greater detail than most other groups of organ- summer 2007 bird trends have also been official isms. Many bird species are at the upper end of the indicators of biodiversity in relation to some of 117 the Swedish Environmental Objectives (www.mil- miljomal.nu). Finally, we were to identify gaps in jomal.nu). present knowledge and propose action to fill them. The situation for many bird species in Sweden is The present paper is a condensed translation of our neither particularly bright. According to the Envi- full report published 2008 in Swedish (Ottvall et ronmental Objectives Council report de Facto 2007, al. 2008). the 2010 goal will be very difficult to achieve. It We used monitoring data and other available in- has been suggested that biodiversity is being lost at formation as a basis for describing population and a slower rate than previously, but that the number of distribution trends for Swedish nesting birds over threatened species will not have been reduced since the past 30 years, focusing on common and fairly 2000. The Swedish Species Information Centre red common species, and in some cases subspecies. We list of threatened species in Sweden has actually have proposed actions to improve the conservation continued to grow, albeit marginally, since the lat- status of vulnerable species or groups of species. est list in 2000 (Gärdenfors 2005). Much less effort was put into looking for changes A much-discussed article in the journal Vår in the geographical range of various species. This is Fågelvärld reported that 46 per cent of Swedish mainly because of a lack of robust data. bird species declined in number during the period 1990–2000 (Ullman 2006). That article was based Methods on figures published in "Birds in Europe: popu- lation estimates, trends and conservation status" Time periods studied (BirdLife International 2004), to which the Swed- In addition to describing population trends1 for ish Ornithological Society contributed trend esti- breeding birds in Sweden over the past 30 years, mates for Sweden. The trend estimates for common we have also chosen to describe developments over species were mainly based on an interpretation of the last 10 years. This is because we consider it results from the Swedish Bird Survey, which pri- important to address the question of how Swedish marily covered parts of southern and central Swe- birds are faring at the moment. For many species, den. For a few species, data from species-specific the three generations period used as a reference projects were used, and in the case of a few other for the National Red List when assessing the de- species data came mainly from spontaneous bird gree to which a species is threatened corresponds observations reported to regional ornithological to approximately 10 years. When evaluating the societies around the country. The assessment of progress of national efforts being made to achieve status and trends for various species were based on the environmental quality objectives, it is also es- various data sources, of which some, but not all, sential to analyse bird data from the last 10-year consisted of systematic surveys. period separately. Moreover, the last decade rough- ly coincides with a number of major changes in ag- riculture and forestry, such as Sweden joining the Aims EU (1995) and the resulting impact of the Com- Because of the seemingly alarming situation we mon Agricultural Policy (CAP), as well as the new were appointed by the Swedish Environmental Pro- Swedish Forestry Act (1993) and the introduction tection Agency (EPA) to provide a coherent picture of forest certification. Economical support for the of population changes over the last few decades creation of wetlands and stricter regulations gov- for all bird species nesting in Sweden, by collat- erning land drainage were also introduced in the ing the best possible available data in a systematic latter part of the 30-year period. In short, a fair and consistent way. Our task was also to collate and number of recent large-scale policy changes have evaluate existing knowledge and explanatory mod- taken place, which may have effects on bird popu- els on the causes of these trends, and, if possible, lations. In addition, during the last decade a new to suggest alternative and additional explanations. bird monitoring scheme, the “Fixed routes” (see In particular, we set out to evaluate how trends re- below), has added new and better data on breeding late to the target on sustainable use of biodiversity bird trends in Sweden. and biological resources as stated in the Swedish This means that the main periods dealt with in Government’s Environmental Objective no. 16 “A Rich Diversity of Plant and Animal Life”. There are 16 Environmental Objectives that set out spe- 1 Unless otherwise specified, the term ”population” here cific goals for various natural habitats and human means the Swedish breeding population of the species/sub- environments, to be achieved in the future (www. species in question. 118 this study are 1977–2006 (the 30-year period) and in small numbers and, where further colonisation 1997–2006 (the 10-year period). We have not ad- is likely, such as Shag Leucocarbo aristotelis and hered rigidly to these years, since some key data re- Stonechat Saxicola torquatus. On the other hand, fer both to the years immediately preceding, and to we have included species that have bred fairly regu- the years immediately following these periods. For larly in Sweden over the last 30 years, but that no instance, the national system of point counts (see longer occur, or do so only sporadically, such as below) began in 1975, and in a few cases census Kentish Plover, Barn Owl, Snowy Owl and Hoo- data from 2007 have also been included (for exam- poe. ple, for wet meadows in Skåne, southern Sweden, and for a few coastal bird censuses). Population changes occurring before the mid-1970s are not Data sources dealt with separately and are not included in any of Most ornithological activity takes place in southern the trends described, but are mentioned when rel- Sweden.