IUCN / SSC Cat Specialist Group - Digital Cat Library |
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| Mowat, G.; Poole, K.G.; O'Donoghue, M. | |
| Ecology of lynx in northern Canada and Alaska | |
| 2000 Book Chapter | |
We review the ecology of lynx in the northern part of its range, drawing heavily on the results of recent research from that region. Snowshoe hares form the bulk of prey items in essentially all studies and at all periods in the cycle, but use of alternative prey, often red squirrel, increases as hares become scarce. Caching of freshly killed prey is rare, although carrion is consumed, primarily during periods of food shortage. Habitat use by lynx varies geographically, but tends to track that of snowshoe hares. Lynx prefer older (>20 years old) regenerating forest stands. Mature forest stands are often used but rarely selected. Most lynx dens found to date have been associated with blowdown or deadfall trees in regenerating stands. Lynx maintain mostly exclusive intrasexual territories, based on social intolerance and mutual avoidance. Male home ranges tend to be larger than female ranges. There appears to be no linear relationship between hare abundance and lynx home range size, although lynx do increase their home range size dramatically following the cyclic hare crash. Male and female home ranges generally overlap completely while within-sex overlap is usually modest; related females may tolerate greater overlap. Lynx numbers fluctuate in synchrony over vast areas and generally lag behind the snowshoe hare cycle by about one year. Peak densities of 30-45 lynx/100 km2 have been observed in regenerating stands, and 8-20/100 km2 in mature forest and more southern ranges. Population densities during the low are <3 lynx/100 km2. Growth in lynx populations is a result of high fecundity, high kit survival, and low adult mortality. The decline is due to increased dispersal, high natural mortality, and a collapse in recruitment. During hare abundance, adult fecundity is high, litter size averages four to five, and yearling lynx give birth. During the cyclic low, recruitment essentially fails for about two years, and is followed by several years of modest recovery. Although trapping is an important mortality source in many areas, natural causes (primarily starvation and predation) account for most detected mortality during the first two years after the hare decline. Fifteen straight-line dispersal distances of 500-1,100 km have been recorded from recent studies in the two northern territories. Dispersal of adults was highest during and following the decline in hare densities. Trapping can reduce lynx populations and can have the greatest impact during the cyclic low, but the long-term impact of trapping on subsequent cycles is unclear. Despite reduced harvests in all jurisdictions and localized overharvest in some areas, no permanent decrease in range has been detected in contiguous northern populations. |
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