National Environmental Research Institute Ministry of the Environment . Denmark The Greenland White-fronted Goose Anser albifrons flavirostris The annual cycle of a migratory herbivore on the European continental fringe Doctor’s dissertation (DSc) Anthony D. Fox [Blank page] National Environmental Research Institute Ministry of the Environment . Denmark The Greenland White-fronted Goose Anser albifrons flavirostris The annual cycle of a migratory herbivore on the European continental fringe Doctor’s dissertation (DSc) 2003 Anthony D. Fox Department of Coastal Zone Ecology Denne afhandling er af det Naturvidenskabelige Fakultet ved Københavns Universitet antaget til offentligt at forsvares for den naturvidenskabelige doktorgrad. København den 14. marts 2003. Data sheet Title: The Greenland White-fronted Goose Anser albifrons flavirostris Subtitle: The annual cycle of a migratory herbivore on the European continental fringe Doctor’s dissertation (DSc) Author: Anthony D. Fox Department: Department of Coastal Zone Ecology Publisher: Ministry of the Environment National Environmental Research Institute URL: http://www.dmu.dk Date of publication: February 2003 Technical editor: Karsten Laursen Financial support: No external support. Please cite as: Fox, A.D. 2003: The Greenland White-fronted Goose Anser albifrons flavirostris. The annual cycle of a migratory herbivore on the European continental fringe. Doctor’s dissertation (DSc). National Environmental Research Institute, Denmark. 440 pp. Reproduction is permitted, provided the source is explicitly acknowledged. Layout: Helle Klareskov ISBN: 87-7772-719-3 Paper quality: Cyclus Print Printed by: Schultz Grafisk Environmentally certified (ISO 14001) and Quality certified (ISO 9002) Number of pages: 440 Cirkulations: 500 Price: DKK 200.- (incl. 25% VAT, excl. freight) Internet-version: The report is also available as a PDF-file from NERI’s homepage http://www.dmu.dk/1_viden/2_publikationer/3_oevrige For sale at: Ministry of the Environment Frontlinien Strandgade 29 DK-1401 København K Tel. +45 32 66 02 00 [email protected] www.frontlinien.dk Contents Summary .........................................................................................................................5 Dansk resumé................................................................................................................. 9 1 Introduction ..................................................................................................... 11 2Limits to population size in recent historical times ................................ 17 3 Accumulation of body stores and the flight to Iceland .......................... 27 4 Spring staging in Iceland and the flight to Greenland ........................... 35 5 Pre-nesting feeding ........................................................................................ 43 6 Reproduction ................................................................................................... 47 7 Moult of flight feathers ................................................................................. 59 8 Survival ............................................................................................................. 65 9 Synthesis........................................................................................................... 73 10 Acknowledgements ........................................................................................ 87 11 References ........................................................................................................ 92 12Appended manuscripts ............................................................................... 101 Appendix 1: Statistical endnotes ............................................................................ 427 Appendix 2: Future Research Priorities ................................................................ 433 National Environmental Research Institute [Blank page] Summary The Greenland White-fronted Goose Anser albi- Consistent with providing advice to support the frons flavirostris is the most morphologically dis- most effective conservation management for the tinct sub-species of the circumpolar White- population, the broad aim of the analysis presented fronted Goose Anser albifrons. The population here is to begin to identify factors that could po- breeds in West Greenland and migrates through tentially limit this population or regulate the rate Iceland to winter in Britain and Ireland. After a of change in its numbers. Given that geese are such period of population decline from the 1950s to social animals, it is especially interesting to exam- the 1970s, protective legislation enacted on the ine how individual behaviour could influence sur- wintering grounds in the early 1980s removed vival and reproduction, and how this scales up to winter hunting as a source of mortality and changes in the overall population. population size doubled to the present level of 30-35,000, although numbers have fluctuated in This thesis therefore examines the annual life cy- very recent years. Declines and extinctions at cle of the Greenland White-fronted Goose, con- some wintering resorts continue, despite the centrating on periods of nutritional and energetic nature conservation objective of maintaining the need (e.g. migration, reproduction and wing current geographical range of the population. feather moult) and the way in which individuals Most research effort has concentrated at the two may balance their short and longer-term budg- most important wintering sites, Wexford Slobs ets. Body mass and field assessments of fat stores in southeast Ireland and the island of Islay off were used as relative measures of body condi- southwest Scotland. These two resorts have sup- tion (taken to represent the ability of an individual ported some 60% of the total population in re- to meet its present and future needs). Greenland cent years. Irish wintering geese tend to stage in White-fronted Geese maintained body mass western Iceland and breed in the north of the through mid winter but accumulated mass in- range in Greenland, whilst Scottish birds tend creasingly until mid April when they depart for to use the southern lowlands of Iceland and Iceland. Assuming 80-90% of this accumulation breed further south. is fat, departing geese had more than enough fuel from such energy stores to sustain this spring Greenland White-fronted Geese habitually feed flight. The majority of this mass was depleted en throughout the annual life cycle on the lower stem route to Iceland where they staged for another of the common cotton grass Eriophorum angusti- c.15 days prior to the journey onwards to Green- folium, which they extract from soft substrates in land. Here, geese increased body mass by 25-30 peatland ecosystems. The restricted extent of pat- grams per day. In total, this is slightly less than terned boglands (which formed the traditional that during December-April but accumulated winter habitat) would undoubtedly have con- over a considerably shorter period. Most Green- strained population size, even in a landscape land White-fronted Geese attained these high unchanged by Man’s activities. Exploitation of rates of mass accumulation on artificially man- this highly specific food in a restricted habitat is aged hayfields although they fed also on adja- also likely to have shaped its highly site-faithful cent wetlands. The three most common grass spe- habit and influenced the evolution of the unusu- cies exploited showed differences in profitability ally prolonged parent-offspring relationships because of differing leaf densities, growth rates which distinguishes this population from most and nutrient quality - all of which affected food other geese. During the last 60 years, the race has intake rates and hence the rate of accumulation increasingly shifted from feeding on natural veg- of stores by geese. Behavioural dominance is a etation habitats to intensively managed agricul- major determinant of access to best food resources tural grasslands, which in some areas has brought in this population. Since individual geese showed the population into conflict with agriculture. De- different levels of feeding specialisation on the spite this change in habitat use, there has been no three grass species there is the potential for den- range expansion, since new feeding traditions sity effects and social status to influence rates of continue to be associated with use of long estab- nutrient acquisition in Iceland that could affect lished night time roost sites. their future fitness. 5 Arrival mass in West Greenland confirmed that causing a decline in wintering numbers there. It geese lost more mass flying from Iceland to may be that the cooling of the climate in North Greenland than during the same flight distance West Greenland and increasing densities further from Iceland to Ireland. The difference was con- south are already affecting the Wexford winter- sistent with the predicted extra costs required to ing birds. At the same time, the Islay wintering cross over the Greenland Ice Cap. After arrival, birds that tend to nest further south, benefit from breeding geese fed intensively for a period of 10- improvements in spring climate conditions in 14 days during which mass accumulation for in- central west Greenland. vestment in reproduction occurred at the same rapid rate as in Iceland. Female geese protected Greenland White-fronted Geese moult flight by attendant ganders were able to exploit a rich feathers