Towards a Solution to the Goose-Agriculture Conflict in North Norway, 1988–2012: The Interplay between Policy,Stakeholder Influence and Goose Population Dynamics

This paper presents results from a multidisciplinary study of a negotiation process between farmers and wildlife authorities which led to an agricultural subsidy scheme to alleviate conflicts between agriculture and geese in Norway. The Svalbard-breeding population of pink-footed geese Anser brachyrhynchus has increased considerably over the last decades and conflicts with farmers have escalated, especially at stopover sites in spring when geese feed on newly sprouted pasture grass. In Vesterålen, an important stopover site for geese in North Norway, farmers deployed scaring of geese at varying intensity dependent on the level of conflict during 1988–2012. We assessed the efficiency of a subsidy scheme established in 2006, in terms of its conflict mitigation, reflected in a near discontinuation of scaring activities. The presence of pink-footed geese was analysed in relation to scaring intensity, the total goose population size and the increasing occurrence of another goose species, the barnacle goose Branta leucopsis. Scaring significantly affected the number of geese staging in Vesterålen, both in absolute and relative terms (controlling for total population size). The geese responded immediately to an increased, and reduced, level of scaring. Despite the establishment of the subsidy scheme, the number of pink-footed geese has recently declined which is probably caused by the increasing number of barnacle geese. For the farmers, the subsidy scheme provides funding that reduces the economic costs caused by the geese. Sustaining a low level of conflict will require close monitoring, dialogue and adaptation of the subsidy scheme to cater for changes in goose population dynamics.     

Pay-offs and penalties of competing migratory schedules

We relate variation in the timing of arrival by migrating birds breeding at northerly latitudes to individual differences in the prior accumulation of energy stores. Balancing starvation risks early in the season against the almost universal declining trend in reproductive prospects with advancing date is seen as an individual decision with fitness consequences. We review three studies implicating events at the staging sites or in winter in setting the individual migratory schedule. Climate change influences the timetable of a pied flycatcher (Ficedula hypoleuca) population breeding in The Netherlands and wintering in West Africa, followed since 1960. Mean air temperature in the period mid April‐mid May (arrival and laying) increased and laying date advanced by 10 days. Still, in recent years most birds did not lay early enough to maximise fitness (determined by recruitment and parental survival) whereas many parents achieved this goal in 1980–1985. As the flycatchers have not started to arrive earlier, some ecological constraint further upstream is postulated (possibly the hurdle of the crossing of Sahara and Mediterranean). The ability to follow individual migrants provides a second avenue to assess the fitness implications of migratory schedules. Thus, brightly coloured male bar‐tailed godwits (Limosa lapponica) captured in the Dutch Wadden Sea (the intermediate staging site linking a West African wintering area with breeding sites in arctic Russia) and traced with miniature radio‐transmitters did not depart early. The ‘best’ males (with bright breeding plumage) were picked up by the listening stations in Sweden 650 km further along the migratory route ten days later than the paler individuals. If early arrival confers the competitive advantage of prior occupancy but increases mortality, the ‘best’ males may be able to afford arriving later and thus avoid some of the survival costs. Return rate of the ‘bright’ males to the staging site in later seasons was indeed higher than for the ‘pale’, early males. Intensive observation of pink‐footed geese (Anser brachyrhynchus) fitted with coded neck‐collars substantiate the tight relationship between energy stores (fat) accumulated up to final departure from the final staging site (Vesterålen, N. Norway) en route to the nesting grounds (Spitsbergen) and subsequent success. The breeding outcome of individual parents (accompanied by juveniles or not) could be related to observations of body condition before departure (visual ‘abdominal profile index’). Recently, perceived conflicts with agriculture have resulted in widespread harassment by humans. The geese have: drastically shortened their stay on the Vesterålen, fail to achieve the body condition usual a decade ago and reproductive output has fallen. Although the geese are currently pioneering new staging sites, an adequate alternative has not materialised, underlining the critical role of the final take‐off site.     

Temperature and precipitation at migratory grounds influence demographic trends of an Arctic‐breeding bird

Anthropogenic climate disruption, including temperature and precipitation regime shifts, has been linked to animal population declines since the mid‐20th century. However, some species, such as Arctic‐breeding geese, have thrived during this period. An increased understanding of how climate disruption might link to demographic rates in thriving species is an important perspective in quantifying the impact of anthropogenic climate disruption on the global state of nature. The Greenland barnacle goose (Branta leucopsis) population has increased tenfold in abundance since the mid‐20th century. A concurrent weather regime shift towards warmer, wetter conditions occurred throughout its range in Greenland (breeding), Ireland and Scotland (wintering) and Iceland (spring and autumn staging). The aim of this study was to determine the relationship between weather and demographic rates of Greenland barnacle geese to discern the role of climate shifts in the population trend. We quantified the relationship between temperature and precipitation and Greenland barnacle goose survival and productivity over a 50 year period from 1968 to 2018. We detected significant positive relationships between warmer, wetter conditions on the Icelandic spring staging grounds and survival. We also detected contrasting relationships between warmer, wetter conditions during autumn staging and survival and productivity, with warm, dry conditions being the most favourable for productivity. Survival increased in the latter part of the study period, supporting the possibility that spring weather regime shifts contributed to the increasing population trend. This may be related to improved forage resources, as warming air temperatures have been shown to improve survival rates in several other Arctic and northern terrestrial herbivorous species through indirect bottom‐up effects on forage availability.     

The onset of spring and timing of migration in two arctic nesting goose populations: the pink‐footed goose Anser bachyrhynchus and the barnacle goose Branta leucopsis

An earlier onset of spring has been recorded for many parts of Eurasia in recent decades. This has consequences for migratory species, both in changing the conditions encountered by individuals on reaching migratory sites and in affecting cues regulating the timing of migration where decisions to migrate are influenced by local environmental variables. Here we examine the timing of spring migration for two arctic goose populations, the pink‐footed goose Anser brachyrhynchus (during 1990–2003) and barnacle goose Branta leucopsis (during 1982–2003), which both breed on Svalbard. The satellite‐derived Normalised Difference Vegetation Index (NDVI) was used to express the onset of spring at their wintering and spring staging sites. Pink‐footed geese use several sites during spring migration, ranging from the southernmost wintering areas in Belgium to two spring staging areas in Norway, and distances between sites used along the flyway are relatively short. There was a positive correlation in the onset of spring between neighbouring sites, and the geese migrated earlier in early springs. Barnacle geese, on the other hand, have a long overseas crossing from their wintering grounds in Britain to spring staging areas in Norway. Although spring advanced in both regions, there was no corresponding correlation in the timing of onset of spring between their wintering and spring staging sites, and little evidence for barnacle geese migrating earlier over the whole study period. Hence, where geese can use spring conditions at one site as an indicator of the conditions they might encounter at the next, they have responded quickly to the advancement of spring, whereas in a situation where they cannot predict, they have not yet responded, despite the advancement of spring in the spring staging area.     

Sharing habitat: Effects of migratory barnacle geese density on meadow breeding waders

• 1.Following targeted conservation actions most goose populations have increased. The growing goose populations caused an increase in human-wildlife conflicts and have the potential to affect nature values. As meadow birds, including meadow-breeding waders, were declining throughout Western Europe, the possible negative effect of rising numbers of foraging barnacle geese on their breeding success has been questioned.
• 2.We used GPS-transmitter data to measure the density of foraging barnacle geese during daylight hours. Using dynamic Brownian Bridge Movement Models (dBBMM), we investigated the effect of barnacle goose density on the territory distribution of five wader species, and on nest success of the locally common Northern lapwing. We used model selection methods to identify the importance of barnacle goose density related to other environmental factors.
• 3.Our results showed an insignificant positive association between barnacle goose density and nest territory density of the Northern lapwing and common redshank. Barnacle goose density had no influence on territory selection of godwit, oystercatcher and ringed plover. We did, however, find a negative correlation between barnacle geese density and the nest success of the Northern Lapwing.
• 4.We infer that either barnacle goose foraging leads to improved territory conditions for some wader species, or that both barnacle geese and waders prefer the same type of habitat for foraging and nesting. Higher barnacle goose density was correlated with fewer Northern lapwing nests being successful.
• 5.Synthesis and application: Experimental research is needed to disentangle the causal chain, but based on our observational findings, we suggest to increase water logging that may attract both barnacle geese and wader species. Further investigation on the effects of barnacle geese on wader species is necessary to identify the cause of the negative correlation between barnacle geese density and nest success of lapwings; nest protection experiments could give further insight.

     

Does intensive goose grazing affect breeding waders?

Increasing goose population sizes gives rise to conflicts with human socioeconomic interests and in some circumstances conservation interests. Grazing by high abundances of geese in grasslands is postulated to lead to a very short and homogeneous sward height negatively affecting cover for breeding meadow birds and impacting survival of nests and chicks. We studied the effects of spring grazing barnacle geese Branta leucopsis and brent geese Branta bernicla on occupancy of extensively farmed freshwater grasslands by nesting and brood‐rearing waders on the island Mandø in the Danish Wadden Sea. We hypothesized that goose grazing would lead to a shorter grass sward, negatively affecting the field occupancy by territorial/nesting and chick‐rearing waders, particularly species preferring taller vegetation. Goose grazing led to a short grass sward (<5 cm height) over most of the island. To achieve a variation in sward height, we kept geese off certain fields using laser light. We analyzed effects of field size, sward height, mosaic structure of the vegetation, proximity to shrub as cover for potential predators, and elevation above ground water level as a measure of wetness on field occupancy by nesting and chick‐rearing waders. The analysis indicated that the most important factor explaining field occupancy by nesting redshank Tringa totanus, black‐tailed godwit Limosa limosa, oystercatcher Haematopus ostralegus and lapwing Vanellus vanellus as well as by chick‐rearing black‐tailed godwit and lapwing was short vegetation height. Distance to shrub cover and elevation were less important. Hence, despite very intensive goose grazing, we could not detect any negative effect on the field occupancy by nesting nor chick‐rearing waders, including redshank and black‐tailed godwit, which are known to favor longer vegetation to conceal their nests and hide their chicks. Possible negative effects may be buffered by mosaic structures in fields and proximity to taller vegetation along fences and ditches.     

Spring migration patterns,habitat use,and stopover site protection status for two declining waterfowl species wintering in China as revealed by satellite tracking

East Asian migratory waterfowl have greatly declined since the 1950s, especially the populations that winter in China. Conservation is severely hampered by the lack of primary information about migration patterns and stopover sites. This study utilizes satellite tracking techniques and advanced spatial analyses to investigate spring migration of the greater white‐fronted goose (Anser albifrons) and tundra bean goose (Anser serrirostris) wintering along the Yangtze River Floodplain. Based on 24 tracks obtained from 21 individuals during the spring of 2015 and 2016, we found that the Northeast China Plain is far‐out the most intensively used stopover site during migration, with geese staying for over 1 month. This region has also been intensely developed for agriculture, suggesting a causal link to the decline in East Asian waterfowl wintering in China. The protection of waterbodies used as roosting area, especially those surrounded by intensive foraging land, is critical for waterfowl survival. Over 90% of the core area used during spring migration is not protected. We suggest that future ground surveys should target these areas to confirm their relevance for migratory waterfowl at the population level, and core roosting area at critical spring‐staging sites should be integrated in the network of protected areas along the flyway. Moreover, the potential bird–human conflict in core stopover area needs to be further studied. Our study illustrates how satellite tracking combined with spatial analyses can provide crucial insights necessary to improve the conservation of declining Migratory species.     

Feeding ecology of barnacle geese on their spring staging grounds in northern Iceland

The distribution and abundance of barnacle geese, Branta leucopsis. staging in northern Iceland was determined in May 1987 and 1994 A similar proportion of the total population (70%) was located in the two years The distribution differed between the two years, with a higher proportion of the geese found in more westerly sites in 1994 Over 80% of records of birds feeding were on improved agricultural pasture though this made up only 47% of the available feeding habitat Some geese fed on riverine and coastal grasslands but this was in a much smaller proportion than the availability of these habitats The number of geese using a site was positively correlated with the area of improved pasture Birds fed intensively through the day, suggesting that the area is important for the accumulation of nutrient stores No differences in habitat use or feeding behaviour were found between 1987 and 1994     

Hazing and movements of Canada geese near Elmendorf Air Force Base in Anchorage, Alaska

Bird strikes to aircraft are a serious economic and safety problem in the United States, annually causing millions of dollars in damage to civilian and military aircraft and the occasional loss of human life. We observed movements of 1236 neckbanded lesser Canada geese (Branta canadensis parvipes) to determine efficacy of hazing as a means to reduce goose presence at Elmendorf Air Force Base (EAFB), Anchorage, Alaska from August to October 1997. Emphasis was on movements of geese onto EAFB with additional data collected at the other two major airports in the area, Anchorage International Airport (AIA) and Merrill Field Airport (MFA). Daily observations indicated the presence of 208 individual neckbanded geese on EAFB, and 20% returned more than once after being hazed from EAFB. We identified three staging areas, geese utilized prior to entering EAFB, and three post-hazing dispersal sites. Collared geese began moving onto EAFB 30–40 days post-molt with the largest proportions moving onto EAFB 70–90 days post-molt. We observed 75 neckbanded geese on AIA from seven molting sites, and 23% returned more than once after being hazed from AIA. We observed 141 neckbanded geese on MFA from 14 molting sites, and 21% returned more than once after being hazed from MFA. Our data indicated that as long as local goose populations increase, large numbers of Anchorage area geese are likely to enter one of the airports creating a variety of management problems. Hazed geese returning to airports multiple times present a special hazard to aircraft safety because they appear to have become habituated to non-lethal scare tactics. We recommend an integrated management approach to limit the Anchorage area goose population utilizing various control techniques which are acceptable to Anchorage residents while continuing the hazing program at area airports.     

Forage plants of an Arctic‐nesting herbivore show larger warming response in breeding than wintering grounds,potentially disrupting migration phenology

During spring migration, herbivorous waterfowl breeding in the Arctic depend on peaks in the supply of nitrogen‐rich forage plants, following a “green wave” of grass growth along their flyway to fuel migration and reproduction. The effects of climate warming on forage plant growth are expected to be larger at the Arctic breeding grounds than in temperate wintering grounds, potentially disrupting this green wave and causing waterfowl to mistime their arrival on the breeding grounds. We studied the potential effect of climate warming on timing of food peaks along the migratory flyway of the Russian population of barnacle geese using a warming experiment with open‐top chambers. We measured the effect of 1.0–1.7°C experimental warming on forage plant biomass and nitrogen concentration at three sites along the migratory flyway (temperate wintering site, temperate spring stopover site, and Arctic breeding site) during 2 months for two consecutive years. We found that experimental warming increased biomass accumulation and sped up the decline in nitrogen concentration of forage plants at the Arctic breeding site but not at temperate wintering and stop‐over sites. Increasing spring temperatures in the Arctic will thus shorten the food peak of nitrogen‐rich forage at the breeding grounds. Our results further suggest an advance of the local food peak in the Arctic under 1–2°C climate warming, which will likely cause migrating geese to mistime their arrival at the breeding grounds, particularly considering the Arctic warms faster than the temperate regions. The combination of a shorter food peak and mistimed arrival is likely to decrease goose reproductive success under climate warming by reducing growth and survival of goslings after hatching.     

Effects of agricultural change on abundance, fitness components and distribution of two arctic-nesting goose populations

Intensification of agriculture since the 1950s has enhanced the availability, competitive ability, crude protein content, digestibility and extended growing seasons of forage grasses. Spilled cereal grain also provides a rich food source in autumn and in winter. Long‐distance migratory herbivorous geese have rapidly exploited these feeding opportunities and most species have shown expansions in range and population size in the last 50 years. Results of long‐term studies are presented from two Arctic‐breeding populations, the Svalbard pink‐footed goose and the Greenland white‐fronted goose (GWFG). GWFGs have shown major habitat shifts since the 1950s from winter use of plant storage organs in natural wetlands to feeding on intensively managed farmland. Declines in local density on, and abandonment of, unmodified traditional wintering habitat and increased reproductive success among those birds wintering on farmland suggest that density‐dependent processes were not the cause of the shift in this winter‐site‐faithful population. Based on enhanced nutrient and energy intake rates, we argue that observed shifts in both species from traditionally used natural habitats to intensively managed farmland on spring staging and wintering areas have not necessarily been the result of habitat destruction. Increased food intake rates and potential demographic benefits resulting from shifts to highly profitable foraging opportunities on increasingly intensively managed farmland, more likely explain increases in goose numbers in these populations. The geographically exploratory behaviour of subdominant individuals enables the discovery and exploitation of new winter feeding opportunities and hence range expansion. Recent destruction of traditional habitats and declines in farming at northern latitudes present fresh challenges to the well being of both populations. More urgently, Canada geese colonizing breeding and moulting habitats of white‐fronted geese in Greenland are further affecting their reproductive output.     

Rapid adaptive adjustment of parental care coincident with altered migratory behaviour

The optimal duration of parental care is shaped by the trade-off between investment in current and expected future reproductive success. A change in migratory behaviour is expected to affect the optimal duration of parental care, because migration and non-migration differ in expectations of future reproductive success as a result of differential adult and/or offspring mortality. Here we studied how a recent emergence of non-migratory behaviour has affected the duration of parental care in the previously (until the 1980s) strictly migratory Russian breeding population of the barnacle geese Branta leucopsis. As a measure of parental care, we compared the vigilance behaviour of parents and non-parents in both migratory and non-migratory barnacle geese throughout the season. We estimated the duration of parental care at 233 days for migratory and 183 days for non-migratory barnacle geese. This constitutes a shortening of the duration of parental care of 21% in 25 years. Barnacle geese are thus able to rapidly adapt their parental care behaviour to ecological conditions associated with altered migratory behaviour. Our study demonstrates that a termination of migratory behaviour resulted in a drastic reduction in parental care and highlights the importance of studying the ecological and behavioural consequences of changes in migratory behaviour and the consequences of these changes for life-history evolution.     

The effects of simulated spring goose grazing on the growth rate and protein content of Phleum pratense leaves

The effects of simulated goose grazing on Phleum pratense plants were tested in an Iceland hayfield during the spring goose staging period (19 April–11 May 1997). Plants in an area exclosed from the influence of grazing and the nutrient effects of goose faeces were subject to the removal of the youngest lamina once, three and four times during this period. Clipping three and four times resulted in 25–41% increases in cumulative elongation of youngest laminae compared with unclipped plants. Total cumulative lamina growth of entire plants showed no significant difference between unclipped plants and those clipped three and four times, hence no overcompensation occurred. Sequential clipping elevated the protein content of the youngest laminae from 20% to 27–33%, whereas there was no change amongst shoots clipped only once. Because geese only consume the youngest lamina of each Phleum plant, measurements from this experiment showed that regular physical removal of growing biomass doubled the biomass of preferred tissue available to geese and increased the potential protein intake 3.5 times at experimental clipping frequencies similar to levels of sequential harvesting observed amongst staging geese compared to less frequent harvesting. These increases were achieved without any fertilising effects of goose faeces implicated in such effects in previous studies. Received: 26 January 1998 / Accepted: 20 March 1998     

Methods of Predicting Risks of Wheat Damage by White-Fronted Geese

Abstract: Accurately predicting occurrence of wildlife damage is crucial for effective management of problematic wildlife species, because accurate predication allows deterrence efforts to be focused at sites or times where damage is most likely. We explored methods to predict occurrence of white-fronted geese (Anser albifrons) grazing in wheat fields around Lake Miyajimanuma, Japan. Depletion of waste rice grains caused geese to forage on wheat leaves in spring, reducing wheat harvest in grazed fields. The cumulative number of goose-days per hectare of rice-planted area from the beginning of the staging period explained the variation in the proportion of geese foraging in wheat fields. A logistic regression model on the location of vulnerable fields showed that goose grazing was likely to occur in wheat fields far from roads and windbreaks and those close to (within 1,000–2,000 m of) previously grazed fields. Although probability of occurrence of goose grazing was initially low in wheat fields with scaring devices, effectiveness of such devices was lost over the 4 survey years. We recommend farmers in the study area prepare counter-damage measures when the cumulative number of goose-days per rice-planted area approaches a threshold above which some geese are predicted to start foraging on wheat (e.g., 199.46 goose-days/ha rice × 28.95 for 10% of geese foraging on wheat). Further, farmers should be aware that grazing on wheat is more likely to occur if wheat fields within 1,000–2,000 m have already been exploited during that particular season and should concentrate deterrence efforts to wheat fields that are far from roads and windbreaks. Systematic deployment of scaring devices over the entire habitat has a risk of accelerating the decline in effectiveness. Thus, we need methods to retard goose habituation to scaring devices, such as scaring with guns, providing alternative feeding sites, and preventing diet change by geese.     

Breeding barnacle geese in Kolokolkova Bay,Russia: number of breeding pairs,reproductive success and morphology

We report the results of an expedition to a barnacle-goose (Branta leucopsis) breeding area in Kolokolkova Bay, west of the lower Pechora delta in northern Russia, undertaken in July 2002. In total, 6 breeding colonies were found within the study area, harbouring 1,324 nests. Mean clutch size was 2.77±0.10 but may have been underestimated because of nest predation. Nest predation was high and correlated with the density of breeding gulls, Larus. The 2002 season was relatively cold and peak hatch occurred late, on 14 July. More than 11,000 barnacle geese were found to moult in the area which, together with the large number of nests found, emphasises the importance of Kolokolkova Bay for barnacle geese. Adult barnacle geese (341) were captured, marked and measured during their annual wing moult. Birds with broods started to moult approximately 2 weeks later than non- and failed breeders. Weight loss during moult was 3 times as rapid as reported for barnacle geese breeding in the Baltic, and a large cost of reproduction seemed to exist in the form of reduced body weight at the onset of moult for birds leading broods. Work in the area will continue over the coming years to document and explain the differences in major life-history parameters, dynamics and environmental effects between arctic and temperate breeding barnacle-goose populations.     

Survival of Svalbard pink-footed geese Anser brachyrhynchus in relation to winter climate, density and land-use

1. Global change may strongly affect population dynamics, but mechanisms remain elusive. Several Arctic goose species have increased considerably during the last decades. Climate, and land-use changes outside the breeding area have been invoked as causes but have not been tested. We analysed the relationships between conditions on wintering and migration staging areas, and survival in Svalbard pink-footed geese Anser brachyrhynchus. Using mark-recapture data from 14 winters (1989-2002) we estimated survival rates and tested for time trends, and effects of climate, goose density and land-use. 2. Resighting rates differed for males and females, were higher for birds recorded during the previous winter and changed smoothly over time. Survival rates did not differ between sexes, varied over time with a nonsignificant negative trend, and were higher for the first interval after marking (0.88-0.97) than afterwards (0.74-0.93). Average survival estimates were 0.967 (SE 0.026) for the first and 0.861 (SE 0.023) for all later survival intervals. 3. We combined 16 winter and spring climate covariates into two principal components axes. F1 was related to warm/wet winters and an early spring on the Norwegian staging areas and F2 to dry/cold winters. We expected that F1 would be positively related to survival and F2 negatively. F1 explained 23% of survival variation (F1,10=3.24; one-sided P=0.051) when alone in a model and 28% (F1,9=4.50; one-sided P=0.031) in a model that assumed a trend for survival. In contrast, neither F2 nor density, land-use, or scaring practices on important Norwegian spring staging areas had discernible effects on survival. 4. Climate change may thus affect goose population dynamics, with warmer winters and earlier springs enhancing survival and fecundity. A possible mechanism is increased food availability on Danish wintering and Norwegian staging areas. As geese are among the main herbivores in Arctic ecosystems, climate change, by increasing goose populations, may have important indirect effects on Arctic vegetation. Our study also highlights the importance of events outside the breeding area for the population dynamics of migrant species.     

Extrapolating herbivore-induced carbon loss across an arctic landscape

A high proportion of the global soil carbon stock is stored in tundra soils. However, populations of arctic-breeding migratory geese including pink-footed geese, Anser brachyrhynchus, are increasing due to agricultural changes and conservation measures in their wintering grounds. Foraging by these geese, which is widespread in extent, reduces the quantity of carbon stored in arctic tundra ecosystems. Here, the potential carbon loss caused by foraging pink-footed geese is modelled across the high-arctic archipelago of Svalbard, combining field experiments, habitat maps and published spatial models of foraging. The carbon loss caused by foraging geese was estimated three growing seasons following perturbation allowing for some recovery to take place. The carbon loss caused by 1-year worth of grubbing was estimated to be 1,700 tonnes, or 37 kg per goose. A total of over 340,000 tonnes of carbon could be affected given an unlimited increase in goose population. Estimated losses were mostly from wetter habitats, which are both carbon rich and highly selected for by foraging geese. The across-landscape carbon loss caused by geese is not great in magnitude in comparison to expected climate-driven carbon losses; however, it is locally severe, and demonstrates how migratory connectivity links processes, such as agricultural change and conservation measures in temperate Europe with carbon dynamics in the high arctic.     

Goose grazing influences the fine-scale structure of a bryophyte community in arctic wetlands

Herbivores can shape plant communities, especially in the Arctic. We tested the role of geese for structuring bryophyte communities at fine spatial scales in the arctic tundra by excluding them from 4 × 4 m areas. We surveyed the presence and absence of bryophyte species in quadrats (10 × 10 cm) divided into 25 cells outside and inside these exclosures, after 5 and 11 years of treatment. Species richness per cell (4 cm²) was higher in the presence of geese, especially after 11 years of treatment, while geese had little effect on richness at larger scales (i.e. quadrat and whole exclosure). The slope of the species–area relationship within quadrats was consequently shallower outside exclosures. Our results further suggest that the community outside the exclosures was more variable in space and time than that inside the exclosures. We conclude that goose foraging activity promotes the coexistence of bryophyte species at the centimetre scale.     

Contrasting consequences of climate change for migratory geese: Predation,density dependence and carryover effects offset benefits of high‐arctic warming

Climate change is most rapid in the Arctic, posing both benefits and challenges for migratory herbivores. However, population‐dynamic responses to climate change are generally difficult to predict, due to concurrent changes in other trophic levels. Migratory species are also exposed to contrasting climate trends and density regimes over the annual cycle. Thus, determining how climate change impacts their population dynamics requires an understanding of how weather directly or indirectly (through trophic interactions and carryover effects) affects reproduction and survival across migratory stages, while accounting for density dependence. Here, we analyse the overall implications of climate change for a local non‐hunted population of high‐arctic Svalbard barnacle geese, Branta leucopsis, using 28 years of individual‐based data. By identifying the main drivers of reproductive stages (egg production, hatching and fledging) and age‐specific survival rates, we quantify their impact on population growth. Recent climate change in Svalbard enhanced egg production and hatching success through positive effects of advanced spring onset (snow melt) and warmer summers (i.e. earlier vegetation green‐up) respectively. Contrastingly, there was a strong temporal decline in fledging probability due to increased local abundance of the Arctic fox, the main predator. While weather during the non‐breeding season influenced geese through a positive effect of temperature (UK wintering grounds) on adult survival and a positive carryover effect of rainfall (spring stopover site in Norway) on egg production, these covariates showed no temporal trends. However, density‐dependent effects occurred throughout the annual cycle, and the steadily increasing total flyway population size caused negative trends in overwinter survival and carryover effects on egg production. The combination of density‐dependent processes and direct and indirect climate change effects across life history stages appeared to stabilize local population size. Our study emphasizes the need for holistic approaches when studying population‐dynamic responses to global change in migratory species.     

Changes in abundance and spatial distribution of geese molting near Teshekpuk Lake,Alaska: interspecific competition or ecological change?

Goose populations molting in the Teshekpuk Lake Special Area of the National Petroleum Reserve—Alaska have changed in size and distribution over the past 30 years. Black brant (Branta bernicla nigricans) are relatively stable in numbers but are shifting from large, inland lakes to salt marshes. Concurrently, populations of greater white-fronted geese (Anser albifrons frontalis) have increased seven fold. Populations of Canada geese (Branta canadensis and/or B. hutchinsii) are stable with little indication of distributional shifts. The lesser snow goose (Anser caerulescens caerulescens) population is proportionally small, but increasing rapidly. Coastline erosion of the Beaufort Sea has altered tundra habitats by allowing saltwater intrusion, which has resulted in shifts in composition of forage plant species. We propose two alternative hypotheses for the observed shift in black brant distribution. Ecological change may have altered optimal foraging habitats for molting birds, or alternatively, interspecific competition between black brant and greater white-fronted geese may be excluding black brant from preferred habitats. Regardless of the causative mechanism, the observed shifts in species distributions are an important consideration for future resource planning.