No abstract

We analysed historic records and annual counts to assess the population status of Vancouver Island marmots (Marmota vancouverensis). Since 1972, marmots have been found at 47 sites on 15 mountains. All but 2 colonies were located within 5 adjacent watersheds on south-central Vancouver Island. Counts underestimated actual marmot abundance. For most site–year combinations, observers probably counted 66–78% of adults and 75–89% of juveniles. Reproductive colonies typically contained fewer than 5 adults ([Formula: see text], SE = 0.61, n = 34). Most animals were found at elevations above 1000 m (81%), on south- to west-facing slopes (74%). After 1981, marmots colonized 11 habitats created by logging of forests above 700 m. Numbers of adults were above average (134–147%) during the early 1980s and have been near or below average since 1990 (58–99%). The current (1995) population contains 100–200 animals, including 50–100 animals in logged habitats. Marmota vancouverensis is rare primarily because of the small size and patchy distribution of natural subalpine meadows on Vancouver Island. The species is apparently adapted to a metapopulation life-style, in which a network of small colonies exhibit population fluctuations, local extinctions and recolonizations over time.

We used radiotelemetry to evaluate seasonal survival rates and mortality factors for a critically endangered island endemic, the Vancouver Island marmot (Marmota vancouverensis Swarth, 1911). Recovery of radio transmitters and marmot remains suggested that predation was the major cause of mortality, accounting for at least 24 of 29 (83%) known-fate deaths recorded since radiotelemetry efforts began in 1992. Wolves (Canis lupus L., 1758) and cougars (Puma concolor (L., 1771)) apparently accounted for 17 deaths (59%). Three marmots (10%) were killed by golden eagles (Aquila chrysaetos (L., 1758)), four (14%) were killed by unknown predators that probably included all of the above species, two (7%) died from unknown causes, and three (10%) died during hibernation in a single burrow. Mortality rates varied seasonally. The daily probability of death during hibernation was very low (P death = 0.016). The probability of death was also low from spring emergence through 31 July (P death = 0.051), but was eight times higher in August (P death = 0.395) and four times higher in September (P death = 0.175). We concluded that predation was the proximate cause of recent declines in wild Vancouver Island marmot populations, that losses were highly concentrated in late summer, and that previous studies exaggerated the importance of winter mortality. We suggest that high predation rates were associated with forestry and altered predator abundance and hunting patterns.Résumé : La radio-télémétrie nous a servi à évaluer le taux saisonnier de survie et les facteurs de mortalité chez la marmotte de l'île de Vancouver (Marmota vancouverensis Swarth, 1911), une espèce endémique insulaire fortement menacée. La récupération des émetteurs et des carcasses de marmottes laisse croire que la prédation est la cause principale de mortalité, représentant au moins 24 (83 %) des 29 cas étudiés depuis le début de l'utilisation de la radio-télé-métrie en 1992. Les loups (Canis lupus L., 1758) et les couguars (Puma concolor (L., 1771)) sont apparemment responsables de 17 (59 %) des morts. Trois (10 %) des marmottes ont été tuées par des aigles royaux (Aquila chrysaetos (L., 1758)) et quatre (14 %) par des prédateurs inconnus qui incluent peut-être toutes les espèces mentionnées pré-cédemment; deux (7 %) sont mortes de causes inconnues et trois (10 %) sont mortes dans un même terrier durant l'hibernation. Les taux de mortalité varient en fonction de la saison. La probabilité quotidienne de mortalité durant l'hibernation est très faible (P mort = 0,016). La probabilité de mortalité est aussi faible de l'émergence printanière jusqu'au 31 juillet (P mort = 0,051), mais elle est huit fois plus élevée en août (P mort = 0,395) et quatre fois plus élevée en septembre (P mort = 0,175). En conclusion, la prédation est la cause immédiate des déclins récents des populations sauvages de marmottes de l'île de Vancouver, les pertes sont fortement concentrées en fin d'été et les études antérieures ont exagéré l'importance de la mortalité hivernale. Nous croyons que ...

2004. Comparision of discriminant function and classification tree analyses for age classification of marmots. Á/ Oikos 105: 575 Á/587.We evaluated the predictive power of two classification techniques, one parametric Á/ discriminant function analysis (DFA) and the other non-parametric Á/ classification and regression tree analysis (CART), in order to provide a non-subjective quantitative method of determining age class in Vancouver Island marmots (Marmota vancouverensis ) and hoary marmots (Marmota caligata ). For both techniques we used morphological measurements of known-age male and female marmots from two independent population studies to build and test predictive models of age class. Both techniques had high predictive power (69 Á/86%) for both sexes and both species. Overall, the two methods performed identically with 81% correct classification. DFA was marginally better at discriminating among older more challenging age classes compared to CART. However, in our test samples, cases with missing values in any of the discriminant variables were deleted and hence unclassified by DFA, whereas CART used values from closely correlated variables to substitute for the missing values. Therefore, overall, CART performed better (CART 81% vs DFA 76%) because of its ability to classify incomplete cases. Correct classification rates were approximately 10% higher for hoary marmots than for Vancouver Island marmots, a result that could be attributed to different sets of morphological measurements. Zygomatic arch breadth measured in hoary marmots was the most important predictor of age class in both sexes using both classification techniques. We recommend that CART analysis be performed on data-sets with incomplete records and used as a variable screening tool prior to DFA on more complete data-sets.

No abstract

I evaluated reproductive rates of the critically endangered Vancouver Island marmot (Marmota vancouverensis Swarth, 1911) using data from captive and wild populations over the 1980–2004 period. Results were similar to those reported for other alpine-dwelling marmots, including the closely related Marmota caligata (Eschscholtz, 1829) and Marmota olympus (Merriam, 1898). Most females in captivity first bred at age 3 or 4 (Tbreed = 4.3 years, SD = 1.15, n = 9), an age not significantly different from that observed in the wild (Tbreed = 3.6 years, SD = 1.2, n = 16). Numbers of pups weaned per litter were similar in captivity (Npups = 3.0, SD = 1.4, n = 25) and in the wild (Npups = 3.4, SD = 1.1, n = 58). Females were capable of weaning pups in consecutive years (46.4%, n = 13) but often skipped 1 year (39.3%, n = 11) or 2 years (14.3%, n = 4) between litters. Two-year-old females weaned pups infrequently (Pbreed = 0.09, n = 43) and older females were far more likely to breed (Pbreed = 0.40, n = 200); in neither case were significant captive-wild differences found. The oldest breeding female was 10 years old, but sample sizes for marmots older than 8 years were small and maximum breeding age may be underestimated. Between-litter intervals in captivity (Tbetween = 1.4 years, SD = 0.7, n = 11) were significantly shorter than in the wild (Tbetween = 1.9 years, SD = 0.7, n = 17). Sex ratios of weaned pups did not differ from 1:1 in the wild (female/male = 1.04) but were significantly skewed towards males in captivity (female/male = 0.56). I conclude that reproductive performance in Vancouver Island marmots is limited both by body condition and social constraints.

2001: Anti-predator behavior of Vancouver Island marmots: using congeners to evaluate abilities of a critically endangered mammal. Ethology 107, 1Ð14. AbstractBehavioral comparisons between endangered species and their congeners may provide valuable data with which to test ideas about declining populations or the future direction of recovery eorts. We considered the case of the highly endangered Vancouver Island marmot (Marmota vancouverensis). Predation is a current source of mortality, and inadequate anti-predator behavior could have profound rami®cations for the future success of re-introductions. We tested whether M. vancouverensis anti-predator behavior was unusual or Ôde®cientÕ by quantifying it and comparing it to 13 other marmot species. We found no evidence that Vancouver Island marmots were unwary. If anything, the converse was true. Vancouver Island marmots were responsive and vigilant towards real and simulated predatory threats. They dug numerous escape burrows that reduced the likelihood of predation. Our results have several implications for future recovery eorts, one of which was to establish ÔbaselineÕ¯ight-response targets that captive-bred Vancouver Island marmots will have to meet or exceed prior to release into predator-rich environments.

I tagged and monitored Vancouver Island marmots (Marmota vancouverensis) to investigate demographic trends among colonies inhabiting natural subalpine meadows and recently logged habitats. Marmota vancouverensis exhibits low reproductive rates, with litter sizes of 2–5 ([Formula: see text], SD = 0.83, n = 36). Females are capable of breeding at age 3, but most animals did not breed until age 4 ([Formula: see text] years, SD = 0.82 years, n = 13), and displayed a nonreproductive interval of at least 1 year between litters ([Formula: see text] years, SD = 0.76 years, n = 6). Persistence of marmots was higher at natural sites than in logged areas (65 versus 48%). Maximum female age was 9 years in natural habitats and 5 years in clearcuts. No adult female inhabiting a clearcut (n = 14) produced more than a single litter, while 5 of 14 females in natural habitats produced 11 litters. The net reproductive value of colonies in clearcut habitats was less than half that of natural colonies (0.25 versus 0.72). Recently logged habitats may act as a demographic "sink" by consuming more dispersers than they produce, and therefore impede the recolonization of distant natural habitats.