Publications

Summary

Monitoring and assessing the impact of pink-footed geese on arctic tundra vegetation is a fundamental part of the ISMP. A study has been published describing and assessing the extent of arctic tundra degradation on Svalbard, Norway caused by grubbing, where pink-footed geese forage for rhizomes below-ground. The study assessed grubbing extent (occurrence of vegetation disturbance) and intensity (proportion of vegetation disturbed) in 2006/07/08 when goose numbers were approximately 56,000 and in 2013 when they increased to approximately 81,000. Despite a 36% increase in population size, in 2013 the grubbing extent at pre-breeding sites was similar to that in 2007/08 but grubbing intensity was lower. The study suggests that extensive snow cover in 2013 probably dispersed geese over larger areas in search of snow-free patches for feeding, thereby reducing grubbing intensity. Whilst, at the largest known breeding site, both grubbing extent and intensity increased with more geese. Birds preferentially fed close to nests in previously grubbed wet habitat, probably aiding nest defence and permitting feeding on plants that were easier to remove from the soil. The study concluded that a greater impact on tundra vegetation may occur at nesting areas if the breeding population continues to grow. However, timing of snowmelt appears key in moderating the impact of disturbance on tundra vegetation since it controls spatial distributions of feeding geese.

The study is described in a paper published in Écoscience and is available on-line.

Citation: Anderson, H. B., J. D. M. Speed, J. Madsen, Å. Ø. Pedersen, I. M. Tombre and R. van der Wal (2016). "Late snow melt moderates herbivore disturbance of the Arctic tundra." Écoscience 23(1-2): 29-39.

Summary

Scaring is often used as a tool to chase geese away from fields, either as a means to protect vulnerable crops or as part of goose management schemes to drive geese to accommodation areas. Geese are quick to habituate to stationary scaring devices; hence, active scaring by humans is often employed. However, few studies have tested how much effort is required for active scaring to be effective. This paper presents the first study to analyse the relationship between active scaring and consequent effects on goose behaviour and field usage, having applied an experimental dose–response framework.

The study provides guidance to farmers and wildlife managers of goose–agricultural conflicts on the efficiency of active scaring with regard to effective dose and optimal timing of scaring. Its results can also be used in a wider socio-economic evaluation to answer questions of whether scaring is cost-effective for individual farmers and, more widely in terms of planning how active scaring can be used in an integrated management design with ‘go’ and ‘no go’ areas for migrating species.

The study is described in a paper published in the Journal of Applied Ecology and is publically available on-line.

A PDF copy is attached:

Summary

This study describes the development in the harvest of the Svalbard Pink-footed Geese in relation to observed changes in population size and migratory behaviour of the population.

In Denmark and Norway the overall hunting bag for pink-feet geese increased stepwise during the 2000s. The population also increased in size over this time but this can only partly explain the change in the hunting bag. It also corresponded to changing patterns in the migratory behaviour of pink-feet, with increased numbers wintering in Denmark and usage of new foraging areas in both Norway and Denmark. This study demonstrates how changes in migratory behaviour and habitat utilisation can abruptly affect exposure to hunting, which showed a functional response to the increased temporal and spatial availability of geese. The paper concludes that the harvest of pink-feet has reached a level likely to cause a population decline. It highlights the need for flexible, internationally coordinated hunting regulations and reliable up-to-date population estimates and hunting bag statistics, to ensure the timely adjustment of management actions.

The study is described in a paper published in PLOSOne and is available on-line.

Part of the data used in this study is available in the Monitoring Data section of this website.

A PDF copy is attached:
 

Summary

A study, using a long-term mark-resighting dataset and scoring of body condition, for the Svalbard-breeding population of pink-footed geese has demonstrate a substantial effect of winter harshness on post-winter body condition. However, this effect was compensated along the spring migration corridor, and did not persist long enough to influence future reproduction. This highlights the importance of temporal scale when assessing impacts of environmental effects, and suggests a state-dependent physiological mechanism adjusting energy accumulation according to internal energy stores carried into spring. In support of these findings, the development of body condition was unaffected by whether geese used supplementary feeding sites or not. While there was no effect of winter harshness on the average population pre-breeding body condition, individual variations in early spring body condition (probably related to different life-histories) were partly traceable throughout spring. This strongly indicates a carry-over effect on the individual level, possibly related to differences in dominance, site use, disturbance or migration strategy, which may potentially affect future reproduction.

The study is described in an article published in PlosOne and is available on-line.

A PDF copy is attached:
 

Summary

Ringing and marking are widely used techniques in avian ecology to assist studies of migration, survival and behaviour, and often used to estimate population sizes. However, only rarely, are the effects of these markings on birds thoroughly tested. Using an abdominal profile index of marked geese and body mass of recaptured birds previously marked, this study investigated the effect of neckbands on body condition of Pink-footed Geese Anser brachyrhynchus to evaluate to what extent capture, handling and banding affected these birds on short, medium and longer terms

Its results indicated that body condition of geese were negatively affected in the days immediately succeeding capture, but that only a minor effect persisted on a seasonal scale. The study found no support for a long-term effect of neckbands on the body mass of individual birds and the long-term effects are expected to be minor. Nevertheless the capture and handling event might be the cause of a temporary decline in body condition. In addition, neckbands might still influence important life-history traits such as reproduction and survival by means of, e.g., altering social interactions, increasing predation or interfering with mate acquisition.

The study is described in an article published in the Journal of Ornithology and is available on-line.

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Summary

This article details a study to investigate the demographic connectivity between the eastern and western flyway populations of pink-footed geese, based on resightings of marked geese from both populations. Previous genetic analyses suggested a modest gene flow between the two populations. This latest analysis reiterated that the two populations currently appear to be demographically closed. The article concluded that, current initiatives to internationally manage the eastern population of pink-footed geese do not need to consider net immigration in predictive harvest models. Furthermore it stated, for waterbirds in general, a targeted approach to evaluate connectivity, using classic marking studies in combination with molecular methods and focussed sampling on breeding grounds, is recommended to better underpin management decisions at population levels.

The article is available on the Wily Online Library as an open-access publication.

For more details please see the attached report:

Summary

This article explores and evaluates the uncertainties associated with the population dynamics and predictive models developed for the pink-footed goose, and how these influence the selection of an optimal harvest strategy for the Svalbard population. In addition, it outlines the gain in management performance (i.e. maintaining a stable population at the desired population size) that could be expected if uncertainty could be eliminated or reduced, and whether an adaptive or robust management strategy might be most appropriate in the face of uncertainty. An adaptive strategy being one where the credibility of the models are periodically revised, whilst a robust strategy is where no learning is anticipated.

The article also emphasises that the implementation of any informed strategy, either adaptive or robust requires an adequate monitoring program. Continuing a ground census count that provides estimates of population size and proportion of young is regard as essential, preferably post-harvest during spring migration (after the impact of any management actions). In addition, for relatively long-lived species like the pink-footed goose, eliminating uncertainty about survival rates used in predictive models provide the greatest gain in management performance.  Furthermore, it is noted that any age dependency in survival also has important implications for how populations respond to harvest. Concerted efforts are recommended to re-assess current rates of survival and acquire either estimates of realized total harvest rates or the age composition of the harvest.
 
For further insights this article is published as an open-access article in Ecological Modelling and is available on-line through Science Direct / Elsevier.

A PDF copy is attached below:

Summary

This document describes the initial work undertaken by Dr. Fred A. Johnson, of the U.S. Geographical Survey, in developing a number of alternative population models used to determine a potential harvest management strategy for the Svalbard Pink-footed Goose. It is recognised that continued development of the population models are part of the on-going process of implementing an Adaptive Harvest Management Strategy for Svalbard Pink-footed Goose. Consequently this work was subsequently further refined by Dr. Johnson and is described in the Adaptive Harvest Management Briefing Summary.

For more details please see the attached report: