Integrating snow science and wildlife ecology in Arctic-boreal North America

Boelman, Natalie T.; Liston, Glen E.; Gurarie, Eliezer; Meddens, Arjan J. H.; Mahoney, Peter J.; Kirchner, P. B.; Bohrer, Gil; Brinkman, Todd J.; Cosgrove, Christopher; Eitel, Jan U. H.; Hebblewhite, Mark; Kimball, J. S.; LaPoint, Scott D.; Nolin, A. W.; Pedersen, Stine Højlund; Prugh, Laura R.; Reinking, Adele K.; Vierling, Lee A.

doi:10.1088/1748-9326/aaeec1

Cited by 69 publications

(95 citation statements)

References 116 publications

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“…, Boelman et al. ). The snow disappearance day that we used to capture snowmelt timing on a large scale is a fairly coarse measure derived from MODIS imagery, which is notoriously prone to missing pixels due to cloud cover.…”

Section: Discussionmentioning

confidence: 99%

“…These properties are, to date, difficult to infer from remotely sensed observations or to acquire via alternative approaches (Boelman et al. ).…”

Section: Discussionmentioning

confidence: 99%

“…, Boelman et al. ). To quantify snow phenology, we used images from NASA's satellite mounted Moderate Resolution Imaging Spectroradiometer (MODIS), obtaining normalized snow difference index at 500‐m resolution.…”

Section: Methodsmentioning

confidence: 99%

“…, Boelman et al. ). Rather than respond to immediate conditions, caribou may be anticipating resources at calving sites in a manner similar to long‐distant migrant birds.…”

Section: Introductionmentioning

confidence: 99%

“…), there is typically very little spring vegetation growth on the northern taiga or tundra during the migration period, and Arctic barren‐ground migrations can take place over largely snow‐covered landscapes (Boelman et al. ). While there is consequently no green wave to surf, caribou may lead or pursue the front of melting snow in a “surfing the snow edge” Arctic analogue.…”

Section: Introductionmentioning

confidence: 99%

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Tactical departures and strategic arrivals: Divergent effects of climate and weather on caribou spring migrations

et al. 2019

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The Arctic has been warming rapidly, affecting ecological processes across the region. Caribou and reindeer (Rangifer tarandus) is a keystone Arctic species undergoing declines in many parts of its range, but definitive links between climate and populations remain elusive. The conspicuous and dramatic mass migration of many caribou populations, during which nearly all pregnant females move from wintering ranges to calving grounds shortly before giving birth, may be an important link between climate and caribou populations. The drivers of migration, however, are similarly mysterious. It is unknown, for example, whether caribou respond to immediate phenological cues, anticipate conditions on calving grounds, or are driven by lagged effects related to physical condition. To investigate the drivers of migration, we analyzed movement data from over 1000 individual caribou from seven major herds, spanning 3000 km across Alaska, Yukon, Northwest Territories (NWT), and Nunavut in Canada, from 1995 to 2017. We developed a hierarchical model to estimate migration departure and arrival times, and analyzed these variables against global climate indices and local weather conditions, exploring immediate and lagged effects, as well as snowmelt timing and vegetation indices. We discovered a continent‐wide synchrony in spring migration departure times, driven mainly by large‐scale, ocean‐driven climate indices (Pacific Decadal Oscillation, Arctic Oscillation, and North Atlantic Oscillation). However, we also found that the speed of migration was highly plastic with later migration departure times followed by shorter migration durations. This plasticity made arrival timing independent of departure timing and its respective drivers. Rather, arrival timing depended strongly on weather conditions from the previous summer: cooler and windier summers generally led to earlier arrival at calving grounds the following year. We suggest that maternal body condition, mainly influenced by conditions that limit insect harassment, is a major factor for earlier spring migration arrival timing, and therefore earlier calving and higher survival rates. We place these results in the context of mechanistic links between climate and caribou population dynamics. Long‐term and large‐scale observations of migratory animals can provide insights into the mechanisms by which long‐distance, collective migrants may adapt to dynamic and unpredictable environments.

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Section: Discussionmentioning

confidence: 99%

“…These properties are, to date, difficult to infer from remotely sensed observations or to acquire via alternative approaches (Boelman et al. ).…”

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…, Boelman et al. ). Rather than respond to immediate conditions, caribou may be anticipating resources at calving sites in a manner similar to long‐distant migrant birds.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Tactical departures and strategic arrivals: Divergent effects of climate and weather on caribou spring migrations

et al. 2019

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The interaction between island geomorphology and environmental parameters drives Adélie penguin breeding phenology on neighboring islands near Palmer Station, Antarctica

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Patterson‐Fraser²,

Stammerjohn

et al. 2019

Ecology and Evolution

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Despite many studies on Adélie penguin breeding phenology, understanding the drivers of clutch initiation dates (CIDs, egg 1 lay date) is limited or lacks consensus. Here, we investigated Adélie penguin CIDs over 25 years (1991–2016) on two neighboring islands, Torgersen and Humble (<1 km apart), in a rapidly warming region near Palmer Station, Antarctica. We found that sea ice was the primary large‐scale driver of CIDs and precipitation was a secondary small‐scale driver that fine‐tunes CID to island‐specific nesting habitat geomorphology. In general, CIDs were earlier (later) when the spring sea ice retreat was earlier (later) and when the preceding annual ice season was shorter (longer). Island‐specific effects related to precipitation and island geomorphology caused greater snow accumulation and delayed CIDs by ~2 days on Torgersen compared to Humble Island. When CIDs on the islands were similar, conditions were mild with less snow across breeding sites. At Torgersen Island, the negative relationship between CID and breeding success highlights detrimental effects of delayed breeding and/or snow on penguin fitness. Past phenological studies reported a relationship between air temperature and CID, assumed to be related to precipitation, but we found air temperature was more highly correlated to sea ice, revealing a misinterpretation of temperature effects. Finally, contrasting trends in CIDs based on temporal shifts in regional sea ice patterns revealed trends toward earlier CIDs (4–6 day advance) from 1979 to 2009 as the annual ice season shortened, and later CIDs (7–10 day delay) from 2010 to 2016 as the annual ice season lengthened. Adélie penguins tracked environmental conditions with flexible breeding phenology, but their life history remains vulnerable to subpolar weather conditions that can delay CIDs and decrease breeding success, especially on landscapes where geomorphology facilitates snow accumulation.

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Sea or summit? Wild reindeer spatial responses to changing high‐arctic winters

et al. 2021

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Because of climate change, wildlife is facing altered environments, including profound shifts in temperature and precipitation regimes. In snow-dominated ecosystems, winter warming and resulting changes in snowpack properties impact forage accessibility for ungulates-often for the worse. The potential of individuals and populations to buffer negative fitness effects of harsh winters with "basal ice" (i.e., ice on the ground) and/or a harder or deeper snowpack depends on their ability to adjust behaviorally through changes in diet, dispersal, or small-scale habitat use. Here, we use ten years of late winter snowpack monitoring and population census data from three neighboring, semi-isolated coastal populations of high-arctic wild Svalbard reindeer to explore small-scale space use responses to annual variation in late winter-foraging conditions. Based on location data from the population censuses, we roughly classified individuals' spatial foraging strategy (i.e., habitat use) during late winter into "tundra" (foraging on tundra plains), "mountain" (foraging at high elevations, with low plant biomass but less snow and ice), or "shore" (foraging along the seashore, subsidizing terrestrial food with kelp and seaweed). Using multinomial logistic regression, we modeled the probability of reindeer adopting either of these strategies as a function of density-dependent winter severity. Our results suggest that effects of winter severity on habitat use are density-dependent and that snowpack depth and hardness (excluding basal ice, measured as "integrated ram hardness," IRH) have stronger influence on reindeer foraging behavior than basal ice, at least at such spatial scales. Particularly, high IRH increased the probability of reindeer seeking high-elevation and steep terrain instead of tundra lowlands, but not at low population density, that is, when competition for food is negligible. This strategy was most pronounced among adult males, possibly reflecting their risk-prone behavior and/or reduced competitiveness related to lack of antlers during winter. This study demonstrates important patterns of temporal, spatial, and demographic variation in reindeer's winter-foraging strategies, adding novel, nuanced insights into how climate change affects spatial processes in isolated ungulate populations. The results add to the impression of considerable behavioral flexibility, which may aid buffering the negative fitness effects of complex changes in foraging conditions due to environmental changes.

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Integrating snow science and wildlife ecology in Arctic-boreal North America

Cited by 69 publications

References 116 publications

Tactical departures and strategic arrivals: Divergent effects of climate and weather on caribou spring migrations

Tactical departures and strategic arrivals: Divergent effects of climate and weather on caribou spring migrations

The interaction between island geomorphology and environmental parameters drives Adélie penguin breeding phenology on neighboring islands near Palmer Station, Antarctica

Sea or summit? Wild reindeer spatial responses to changing high‐arctic winters

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