Long-term fluctuations of a caribou population revealed by tree-ring data

Morneau, Claude; Payette, Serge

doi:10.1139/z00-122

Cited by 33 publications

(10 citation statements)

References 18 publications

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“…Understanding reproduction of migratory caribou is of particular interest because populations undergo rapid and extensive fluctuations (Morneau and Payette 2000). Reproduction is one of the first vital rates affected by an increase in population size in migratory populations (Crête et al 1996).…”

Section: Introductionmentioning

confidence: 99%

Spring-loaded reproduction: effects of body condition and population size on fertility in migratory caribou (Rangifer tarandus)

2013

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In many ungulates, female fecundity is affected by body condition and has important effects on population dynamics. In some species, females adopt a conservative strategy, reducing reproductive effort when population density is high. We investigated what factors affect the probability of gestation in adult female caribou (Rangifer tarandus (L., 1758)) from the Rivière-George herd in northern Quebec and Labrador over 5 years that spanned various population sizes and trends. Similar to other populations of migratory caribou, the probability that a female was pregnant in spring increased with body mass and percent body fat. The probability of gestation appeared to be reduced by high infestation of warbles (Hypoderma tarandi (L., 1758)). The proportion of females pregnant varied between years and was lower at high population size. Females of similar mass, however, were pregnant regardless of whether the population was increasing at low density, had reached a peak, or was declining. Compared with other ungulates that reduce maternal expenditure at high density, female caribou of the Rivière-George herd may have a risk-prone reproductive strategy.Résumé : Chez de nombreux ongulés, la condition corporelle a une incidence sur la fécondité des femelles qui, elle, a des effets importants sur la dynamique des populations. Les femelles de certaines espèces adoptent notamment une stratégie conservatrice consistant à réduire leur effort de reproduction quand la densité de la population est élevée. Nous avons examiné les facteurs qui influent sur la probabilité de gestation des caribous (Rangifer tarandus (L., 1758)) femelles adultes du troupeau de Rivière-George, dans le nord du Québec et au Labrador, sur une période de 5 ans couvrant diverses tailles et tendances de population. À l'instar d'autres populations de caribous migrateurs, plus la masse corporelle et le pourcentage de graisse corporelle étaient élevés, plus la probabilité qu'une femelle soit en gestation au printemps était grande. Un degré élevé d'infestation d'hypodermes (Hypoderma tarandi (L., 1758)) semblait se traduire par une probabilité de gestation réduite. La proportion de femelles gestantes variait selon l'année et était plus faible lorsque la taille de la population était grande. Cependant, les femelles de masses semblables étaient gestantes peu importe si la taille de la population augmentait à faible densité, avait atteint un maximum ou était en baisse. Comparativement à d'autres ongulés qui adoptent une stratégie de réduction des dépenses maternelles quand la densité est élevée, les caribous femelles du troupeau de Rivière-George pourraient présenter une stratégie de reproduction risquée. [Traduit par la Rédaction]

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Section: Introductionmentioning

confidence: 99%

Spring-loaded reproduction: effects of body condition and population size on fertility in migratory caribou (Rangifer tarandus)

2013

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“…Age-frequency distributions of trampling scars by 10-year age-classes were constructed. Underestimation of caribou trampling as one goes back in time was taken into account, assuming a constant loss of scars with time based on the removal of the exponential trend from the age structures using log-linear regressions (35). The number of scars in each study stand was log-transformed after one year was added to each age-class to avoid value 0.…”

Section: Methodsmentioning

confidence: 99%

“…Also two periods of minor caribou activity prevailed during several decades both in the 19 th and the 20 th centuries, separated by a somewhat low-to-moderate increase from the late 1800s to the early 1900s. The comparison between the RAF chronology and the GEOR chronology from eastern Québec-Labrador (35) shows that RAF experienced an increase of lesser magnitude during the late 1800s -early 1900s. It is possible that this lower increase in caribou activity was due to sustained harvesting by the Nunamiut.…”

Section: -Year Record Of Caribou Activity and Native Harvestingmentioning

confidence: 99%

Long-term Interactions between Migratory Caribou, Wildfires and Nunavik Hunters Inferred from Tree Rings

Payette

Boudreau²,

Morneau³

et al. 2004

AMBIO: A Journal of the Human Environment

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Barren-ground caribou (Rangifer tarandus) herds in North America may reach considerable size and undertake large-scale seasonal migrations from the Arctic tundra to the boreal forest. To test the caribou decline hypothesis associated with native harvesting and fire, we have documented the long-term trends of caribou activity based on a novel approach which uses tree-ring dated trampling scars produced by caribou hooves in the extensive trails distributed over the summer and winter ranges of the Rivièreaux-Feuilles herd (RAF herd, east of Hudson Bay in northern Quebec). The age structure data of trampling scars from lichen woodlands distributed over the entire RAF range confirmed the overall trends of caribou activity from the late 1700s to present time. Over the last 200 years, the RAF herd has undergone two highs in the late 1700s and 1900s separated by a moderate activity pattern in the late 1800s. Native harvesting was possibly involved in the early 1900s decline, although at a moderate level. The reduced magnitude of caribou activity during this period has not modified the natural cycle of highs and lows, which suggests that other demographic factors were controlling the changing caribou abundance. Our data also show that only exceptionally large fires may have a minor, short-lived impact on caribou migrations but not on caribou numbers.

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“…Changes in dispersal rates do not occur independently from changes in abundance. Population abundance and distribution vary through regular fluctuations, with periods of high and low abundance (Morneau & Payette, 1998;Morneau & Payette, 2000;Zalatan et al, 2006;Bergerud et al, 2008), which likely influences dispersal and colonization of unoccupied ranges. Some of the annual variation in gene flow likely reflects caribou movement when population sizes were high and the likelihood of dispersal was greatest.…”

Section: Gene Flow Patternsmentioning

confidence: 99%

Genetic diversity, structure and gene flow of migratory barren-ground caribou (Rangifer tarandus groenlandicus) in Canada

McFarlane

Gunn²,

Campbell

et al. 2016

Ran

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Migratory barren-ground caribou (Rangifer tarandus groenlandicus) provide an opportunity to examine the genetic population structure of a migratory large mammal whose movements and distribution, in some instances, have not been heavily influenced by human activities that result in habitat loss or fragmentation. These caribou have likely reached large effective population sizes since their rapid radiation during the early Holocene despite cyclic changes in abundance. Migratory barren-ground caribou are managed as discrete subpopulations. We investigated genetic variation among those subpopulations to determine the patterns of genetic diversity within and among them, and the implications for long-term persistence of caribou. We identified three distinct genetic clusters across the Canadian arctic tundra: the first cluster consisted of all fully-continental migratory barren-ground subpopulations; the second cluster was the Dolphin and Union caribou; and the third cluster was caribou from Southampton Island. The Southampton Island caribou are especially genetically distinct from the other barren-ground type caribou. Gene flow among subpopulations varied across the range. Occasional gene flow across the sea-ice is likely the reason for high levels of genetic variation in the Dolphin and Union subpopulation, which experienced very low numbers in the past. These results suggest that for most migratory caribou subpopulations, connectivity among subpopulations plays an important role in maintaining natural genetic diversity. Our analyses provide insight into the levels of microsatellite genetic diversity and patterns of gene flow that may be common to large subpopulations that historically had a continuous distribution across a large continental range. These data can also be used as a benchmark to compare the effects of habitat fragmentation and bottlenecks on other large caribou populations.

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Long-term fluctuations of a caribou population revealed by tree-ring data

Cited by 33 publications

References 18 publications

Spring-loaded reproduction: effects of body condition and population size on fertility in migratory caribou (Rangifer tarandus)

Spring-loaded reproduction: effects of body condition and population size on fertility in migratory caribou (Rangifer tarandus)

Long-term Interactions between Migratory Caribou, Wildfires and Nunavik Hunters Inferred from Tree Rings

Genetic diversity, structure and gene flow of migratory barren-ground caribou (Rangifer tarandus groenlandicus) in Canada

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