Arctic-breeding Species Research Articles

Achieving international biodiversity targets: Learning from local norms, values and actions regarding migratory waterfowl management in Kazakhstan.

Migratory species are protected under international legislation; their seasonal movements across international borders may therefore present opportunities for understanding how global conservation policies translate to local‐level actions across different socio‐ecological contexts. Moreover, local‐level management of migratory species can reveal how culture and governance affects progress towards achieving global targets. Here, we investigate potential misalignment in the two‐way relationship between global‐level conservation policies (i.e. hunting bans and quotas) and local‐level norms, values and actions (i.e. legal and illegal hunting) in the context of waterfowl hunting in northern Kazakhstan as a case‐study.Northern Kazakhstan is globally important for waterfowl and a key staging area for arctic‐breeding species. Hunting is managed through licences, quotas and seasonal bans under UN‐AEWA intergovernmental agreements. To better understand the local socio‐ecological context of waterfowl hunting, we take a mixed‐methods approach using socio‐ecological surveys, informal discussions and population modelling of a focal migratory goose species to: (a) investigate motivations for hunting in relation to socio‐economic factors; (b) assess knowledge of species' protection status; and (c) predict the population size of Lesser White‐fronted Geese (LWfG; Anser erythropus; IUCN Vulnerable) under different scenarios of survival rates and hunting offtake, to understand how goose population demographics interact with the local socio‐ecological context.Model results showed no evidence that waterfowl hunting is motivated by financial gain; social and cultural importance were stronger factors. The majority of hunters are knowledgeable about species' protection status; however, 11% did not know LWfG are protected, highlighting a key area for increased stakeholder engagement.Simulations of LWfG population growth over a 20‐year period showed LWfG are highly vulnerable to hunting pressure even when survival rates are high. This potential impact of hunting highlights the need for effective regulation along the entire flyway; our survey results show that hunters were generally compliant with newly introduced hunting regulations, showing that effective regulation is possible on a local level. Synthesis and applications. Here, we investigate how global conservation policy and local norms interact to affect the management of a threatened migratory species, which is particularly important for the protection and sustainable management of wildlife that crosses international borders where local contexts may differ. Our study highlights that to be effective and sustainable in the long‐term, global conservation policies must fully integrate local socio‐economic, cultural, governance and environmental contexts, to ensure interventions are equitable across entire species' ranges. This approach is relevant and adaptable for different contexts involving the conservation of wide‐ranging and migratory species, including the 255 migratory waterfowl covered by UN‐AEWA (United Nations Agreement on the Conservation of African‐Eurasian Migratory Waterbirds).

Pro-inflammatory immune response is linked to wintering habitat in a migratory shorebird

AbstractMigratory shorebirds (Charadrii) show a strong dichotomy in their breeding and wintering strategies: Arctic-breeding species typically spend the wintering season in marine habitats, while more southerly breeding species tend to do so in freshwater habitats where pathogens and parasites, particularly vector-borne blood parasites, are generally more abundant. Thus, it has been hypothesized that the former group may reduce their investment in immunity, but experimental data supporting this hypothesis are lacking. Moreover, whether this contrasting habitat selection can shape investments in immunocompetence among populations within a species is uncertain. We experimentally tested the hypothesis that there is a significant association between habitat occupancy and the strength of a pro-inflammatory immune response in the Dunlin (Calidris alpina), a widely distributed long-distance migratory shorebird that breeds in (sub-)arctic areas and winters mainly, but not exclusively, in coastal habitats. Overwintering Dunlins occupying inland freshwater and marine habitats at a similar latitude were captured and acclimated under identical conditions in outdoor aviaries. After an acclimation period, they were challenged with phytohemagglutinin to assess the pro-inflammatory immune response and its associated energetic costs, measured by basal metabolic rate (BMR) and body mass changes. We found that freshwater Dunlins exhibited a higher (63%) pro-inflammatory immune response than marine Dunlins. Although this difference did not involve significant BMR changes, the time course of body mass response differed between freshwater and marine individuals. Our findings point to the existence of different pro-inflammatory immune responses and body mass adjustments associated with the wintering habitat. These intraspecific differences are likely due to population adaptation rather than phenotypic plasticity, where not only disease risk but also physiological adaptations to different salinity levels could play an important role.

Population fitness has a concave relationship with migration distance in Sanderlings

In Focus: Reneerkens, J., Versluijs, T. S. L., Piersma, T., Alves, J. A., Boorman, M., Corse, C., … Lok, T. (2020). Low fitness at low latitudes: wintering in the tropics increases migratory delays and mortality rates in an Arctic breeding shorebird. Journal of Animal Ecology, 89, 691-703. A central question in migratory ecology has been to understand the fitness consequences of individual variation in migration distance among different species and populations. Reneerkens et al. (2020) investigated the demographic consequences of long-distance migration for Sanderlings Calidris alba, an Arctic-breeding species of sandpiper. Their study population has a remarkable geographic distribution with a breeding range that is concentrated in northeast Greenland and Ellesmere Island, Canada but a nonbreeding range that extends across 85° of latitude from Scotland to Namibia. The authors report on unexpected patterns of latitudinal variation in three demographic parameters: timing of passage on northward migration, probability of juvenile migration and apparent survival of adults. Sanderlings travelling 1,800-2,800km to settle at north temperate sites during the nonbreeding season hadearlier passage dates, and also higher probabilities of migration and apparent survival. In contrast, birds travelling 6,000-7,800km to equatorial sites experienced later passage dates, delayed maturity and lower apparent survival. However, if Sanderlings migrated even farther and flew over 11,000km to nonbreeding sites in Namibia, then their performance was restored to early passage dates and higher survival. Movement tracks from birds tagged with geolocators showed that birds wintering in Namibia make nonstop flights of 7,500km that bypass West Africa during northward migration. Thus, all lines of evidence suggest that Sanderlings face adversity when spending the nonbreeding season at equatorial latitudes. Moreover, the central finding that components of fitness can have nonlinear relationships with migration distance is a novel discovery that leads to many additional questions. The new findings have broader implications for theoretical models of migration, and for understanding how different patterns of movements may arise or be maintained in migratory species.

Evaluating the efficacy of eBird data for modeling historical population trajectories of North American birds and for monitoring populations of boreal and Arctic breeding species

Walker, J., and P. D. Taylor. 2020. Evaluating the efficacy of eBird data for modeling historical population trajectories of North American birds and for monitoring populations of boreal and Arctic breeding species. Avian Conservation and Ecology 15(2):10. https://doi.org/10.5751/ACE-01671-150210

Sources of diel variation in energetic physiology in an Arctic-breeding, diving seaduck

Diel variation in baseline glucocorticoid (GC) secretion influences energetics and foraging behaviors. In temperate breeding, diurnal vertebrates, studies have shown that daily patterns of baseline GC secretion are influenced by environmental photoperiod, with baseline GCs peaking prior to sunrise to stimulate waking and foraging behaviors. Measures of physiological energy acquisition are also expected to peak in response to foraging activity, but their relationship to GC levels have not been well studied. In contrast to temperate breeding species, virtually nothing is known about diel GC and energetic metabolite secretion in Arctic breeding species, which experience almost constant photoperiods in spring and summer. Using a ten-year dataset, we examined the daily, 24-h pattern of baseline corticosterone (CORT) and triglyceride (TRIG) secretion in approximately 800 female pre-breeding Arctic-nesting common eiders (Somateria mollissima). We related these traits to environmental photoperiod and to tidal cycle. In contrast to temperate breeding species, we found that that neither time of day nor tidal trend predicted diel variation in CORT or TRIG secretion in Arctic-breeding eiders. Given the narrow window of opportunity for breeding in polar regions, we suggest that eiders must decouple their daily foraging activity from light and tidal cycles if they are to accrue sufficient energy for successful breeding. As CORT is known to influence foraging behavior, the absence of a distinct diel pattern of CORT secretion may therefore be an adaptation to optimize reproductive investment and likelihood for success in some polar-breeding species.

Division of parental duties confirms a need for bi-parental care in a precocial bird, the mute swan Cygnus olor

Parental investment is much reduced in precocial species when compared with altricial species, which may explain a predominance of uni-parental care in this group of birds. In precocial wildfowl, bi-parental care is mostly restricted to arctic-breeding species, where the short reproductive season forces mates to cooperate in caring for the young, but a temperate breeding mute swanCygnus oloris one of the few notable exceptions. In order to explain a need for bi-parental care in this species, we collected data on the time-budget of eleven swan breeding pairs from a Central European population. We found sex-related differences in the mean time allocated to incubation, movement, feeding, resting and aggression. Others behaviours (nest maintenance, alert and comfort) changed along the breeding season, but did not differ between sexes. Females were primarily responsible for providing care to the brood, whereas male activity focused on territory defence and family guarding. Females were exclusively responsible for incubation and they covered 85% of the total time allocated by parents to feeding cygnets. Nearly constant incubation in females limited possibilities for other activities, including foraging. Males allocated significantly more time than females to aggressive interactions, directed mainly towards other breeding pairs and non-breeders. A clear division of parental duties between sexes gave empirical support for the presence of bi-parental care in the mute swan, despite the fact that reproductive activities of this species are not constrained by the short length of the breeding season, as in arctic-breeding wildfowl.

Forecasting spring from afar? Timing of migration and predictability of phenology along different migration routes of an avian herbivore.

Herbivorous birds are hypothesized to migrate in spring along a seasonal gradient of plant profitability towards their breeding grounds (green wave hypothesis). For Arctic breeding species in particular, following highly profitable food is important, so that they can replenish resources along the way and arrive in optimal body condition to start breeding early. We compared the timing of migratory movements of Arctic breeding geese on different flyways to examine whether flyways differed in the predictability of spring conditions at stopovers and whether this was reflected in the degree to which birds were following the green wave. Barnacle geese (Branta leucopsis) were tracked with solar GPS/ARGOS PTTs from their wintering grounds to breeding sites in Greenland (N=7), Svalbard (N=21) and the Barents Sea (N=12). The numerous stopover sites of all birds were combined into a set of 16 general stopover regions. The predictability of climatic conditions along the flyways was calculated as the correlation and slope between onsets of spring at consecutive stopovers. These values differed between sites, mainly because of the presence or absence of ecological barriers. Goose arrival at stopovers was more closely tied to the local onset of spring when predictability was higher and when geese attempted breeding that year. All birds arrived at early stopovers after the onset of spring and arrived at the breeding grounds before the onset of spring, thus overtaking the green wave. This is in accordance with patterns expected for capital breeders: first, they must come into condition; at intermediate stopovers, arrival with the food quality peak is important to stay in condition, and at the breeding grounds, early arrival is favoured so that hatching of young can coincide with the peak of food quality. Our results suggest that a chain of correlations between climatic conditions at subsequent stopovers enables geese to closely track the green wave. However, the birds' precision of migratory timing seems uninfluenced by ecological barriers, indicating partly fixed migration schedules. These might become non-optimal due to climate warming and preclude accurate timing of long-distance migrants in the future.

Phenological advancement in arctic bird species: relative importance of snow melt and ecological factors

Previous studies have documented advancement in clutch initiation dates (CIDs) in response to climate change, most notably for temperate-breeding passerines. Despite accelerated climate change in the Arctic, few studies have examined nest phenology shifts in arctic breeding species. We investigated whether CIDs have advanced for the most abundant breeding shorebird and passerine species at a long-term monitoring site in arctic Alaska. We pooled data from three additional nearby sites to determine the explanatory power of snow melt and ecological variables (predator abundance, green-up) on changes in breeding phenology. As predicted, all species (semipalmated sandpiper, Calidris pusilla, pectoral sandpiper, Calidris melanotos, red-necked phalarope, Phalaropus lobatus, red phalarope, Phalaropus fulicarius, Lapland longspur, Calcarius lapponicus) exhibited advanced CIDs ranging from 0.40 to 0.80 days/year over 9 years. Timing of snow melt was the most important variable in explaining clutch initiation advancement (“climate/snow hypothesis”) for four of the five species, while green-up was a much less important explanatory factor. We found no evidence that high predator abundances led to earlier laying dates (“predator/re-nest hypothesis”). Our results support previous arctic studies in that climate change in the cryosphere will have a strong impact on nesting phenology although factors explaining changes in nest phenology are not necessarily uniform across the entire Arctic. Our results suggest some arctic-breeding shorebird and passerine species are altering their breeding phenology to initiate nesting earlier enabling them to, at least temporarily, avoid the negative consequences of a trophic mismatch.

First Report of a Snow Bunting × Lapland Longspur Hybrid

In late April 2011, photographs of an apparent male snow bunting ( Plectrophenax nivalis ) × Lapland longspur ( Calcarius lapponicus ) hybrid were taken at St. Lewis Inlet, Newfoundland and Labrador, Canada, while the bird was foraging in a mixed flock of both species along a previously documented spring migratory route. As far as we are aware, this is the first hybridization of these species documented anywhere in the world. The bird was identified as a male on the basis of longspur nape coloration, and it appears to have the head, beak, and back coloration and patterning of a Lapland longspur, but the chin, chest and throat, and overall appearance of a snow bunting. Although our research team has banded more than 50 000 birds of both species over the past 30 years across the latitudinal range of both species, we have never observed such a hybrid. While these Arctic-breeding species overlap spatially and temporally during wintering, migration, and breeding, longspurs and buntings have distinct sexual characters and breed in different ecological niches, which may account for the reproductive isolation or low rates of hybridization of these species. While we were unable to conduct detailed morphological or genetic comparisons on this particular individual for phylogenic interpretation, this report highlights the importance of reporting field observations that may indicate ecological changes affecting the hybridization rates of these inaccessible Arctic species.

Breeding dispersal in a heterogeneous landscape: the influence of habitat and nesting success in greater snow geese

Despite numerous studies on breeding dispersal, it is still unclear how habitat heterogeneity and previous nesting success interact to determine nest-site fidelity at various spatial scales. In this context, we investigated factors affecting breeding dispersal in greater snow geese (Anser caerulescens atlanticus), an Arctic breeding species nesting in two contrasting habitats (wetlands and mesic tundra) with variable pattern of snowmelt at the time of settlement in spring. From 1994 to 2005, we monitored the nesting success and breeding dispersal of individually marked females. We found that snow geese showed a moderate amount of nest-site fidelity and considerable individual variability in dispersal distance over consecutive nesting attempts. This variability can be partly accounted for by the annual timing of snowmelt. Despite this environmental constraint, habitat differences at the colony level consistently affected nesting success and settlement patterns. Females nesting in wetlands had higher nesting success than those nesting in mesic tundra. Moreover, geese responded adaptively to spatial heterogeneity by showing fidelity to their nesting habitat, independently of snowmelt pattern. From year to year, geese were more likely to move from mesic to high-quality wetland habitat, regardless of previous nesting success and without cost on their subsequent nesting performance. The unpredictability of snowmelt and the low cost of changing site apparently favour breeding-site dispersal although habitat quality promotes fidelity at the scale of habitat patches.

Disease‐limited distributions? Contrasts in the prevalence of avian malaria in shorebird species using marine and freshwater habitats

Migratory shorebirds show strong dichotomies in habitat choice during both the breeding and nonbreeding season. Whereas High Arctic breeding species are restricted to coastal marine and saline habitats during the nonbreeding season, more southerly breeding species tend to use freshwater habitats away from coasts. It has been proposed that this co‐variation in habitat use is a consequence of a single axis of adaptation to pathogens and parasites, which are hypothesized to be relatively scarce in High Arctic, marine, and saline habitats and relatively common at lower latitudes and in freshwater habitats. Here we examine this contrast by comparing the prevalence of avian malaria infections in shorebirds occupying different habitats. We used a PCR‐based assay on 1319 individuals from 31 shorebird species sampled in the Arctic, in temperate Europe and in inland and marine habitats in West Africa. Infections mainly occurred in tropical wetlands, with the shorebirds in freshwater inland habitats having significantly higher prevalence of malaria than birds in marine coastal habitats. Infections were not found in birds migrating through Europe even though conspecifics did show infections in tropical Africa. Adults should resist infection better than juveniles, but showed higher malaria prevalence, suggesting that infection probability increases with cumulative exposure. We argue that exposure to vectors is the main factor explaining the habitat‐related differences in malaria prevalence.

Modulating the Corticosterone Stress Response: A Mechanism for Balancing Individual Risk and Reproductive Success in Arctic-Breeding Sparrows?

Abstract Modulation of the adrenocortical stress response with respect to the degree of parental activity was investigated in three Arctic-breeding species of songbirds faced with limited opportunities to breed. The hypothesis that the strength of the response can be lowered when reproductive effort or investment is greatest was tested by measuring the adrenocortical response to handling stress during two breeding stages that represented different levels of reproductive effort (i.e. before young were present [preparental] and while feeding nestlings [parental]). Comparisons of the corticosterone stress response (baseline at capture and subsequent samples 5, 10, 30, and 60 min after capture) were made within and between both sexes of American Tree Sparrows (Spizella arborea), White-crowned Sparrows (Zonotrichia leucophrys gambelii), and Savannah Sparrows (Passerculus sandwichensis) breeding above the Arctic Circle at Toolik Lake, Alaska. In general, body mass and baseline corticosterone did not differ between sexes within each of the three species, nor did they change during the two stages of breeding (tree and White-crowned sparrows only). In all three species, males had stronger adrenocortical responses than females during the preparental period, a time when males may expend less in reproductive effort than females. However, during the parental stage (tree and White-crowned sparrows only), the stress response of males declined and became similar to that of females because both sexes fed young. Females of both species (having considerable reproductive effort throughout both stages via egg laying or incubation and feeding young) showed no change in stress response with breeding stage. These results support the hypothesis that individuals with limited opportunities to breed can modulate the adrenocortical stress response when reproductive effort or investment is greatest as a way to maximize breeding success.

MODULATING THE CORTICOSTERONE STRESS RESPONSE: A MECHANISM FOR BALANCING INDIVIDUAL RISK AND REPRODUCTIVE SUCCESS IN ARCTIC-BREEDING SPARROWS?

Abstract Modulation of the adrenocortical stress response with respect to the degree of parental activity was investigated in three Arctic-breeding species of songbirds faced with limited opportunities to breed. The hypothesis that the strength of the response can be lowered when reproductive effort or investment is greatest was tested by measuring the adrenocortical response to handling stress during two breeding stages that represented different levels of reproductive effort (i.e. before young were present [preparental] and while feeding nestlings [parental]). Comparisons of the corticosterone stress response (baseline at capture and subsequent samples 5, 10, 30, and 60 min after capture) were made within and between both sexes of American Tree Sparrows (Spizella arborea), White-crowned Sparrows (Zonotrichia leucophrys gambelii), and Savannah Sparrows (Passerculus sandwichensis) breeding above the Arctic Circle at Toolik Lake, Alaska. In general, body mass and baseline corticosterone did not differ betw...