A geographic analysis of snowshoe hare population demography

2000 ◽  
Vol 78 (7) ◽  
pp. 1207-1217 ◽  
Author(s):  
Dennis L Murray
Keyword(s):  
Survival Rates ◽  
Latitudinal Gradients ◽  
Snowshoe Hare ◽  
Lynx Lynx ◽  
Lynx Canadensis ◽  
Differential Survival ◽  
Northern Latitudes ◽  
Total Productivity ◽  
Reproductive Rates ◽  
Demographic Attributes

Snowshoe hare (Lepus americanus) populations across northern Canada and Alaska undergo 8- to 11-year cycles in numbers, but population trends in southern Canada and the contiguous United States are apparently either weakly cyclic, irruptive, or largely stable. Although the demographic attributes (population density, reproductive rates, and survival rates) of northern and southern hare populations should differ considerably to account for such differential trends, to date limited rangewide analyses of hare demography have been undertaken. I reviewed hunter harvest estimates and basic demographic attributes for hare populations across North America, and assessed the effect of latitude, longitude, and latitude × longitude interaction on the magnitude and variation of such attributes. Harvest estimates tended to be synchronous across the Great Lakes area and along the St. Lawrence River, whereas they varied more dramatically along a westward gradient and in hare populations suspected of being cyclic. Hare densities tended to be higher among apparently noncyclic than cyclic populations at numerical lows, as well as among studies where hare numbers were apparently increasing. Populations from northern latitudes tended to breed later than those in the south, and females from western areas produced larger, but fewer litters, than those from eastern populations; total productivity was similar across geographic areas. Survival rates for both adult and juvenile hares were higher in increasing populations than in decreasing populations. Survival of adults also decreased along a northwest gradient, whereas that of juveniles decreased across a western gradient and with longitude, was lower in apparently noncyclic populations, and was also lower in populations in areas of high lynx (Lynx canadensis) densities. I conclude that, although disparity clearly exists in the trends of various hare populations, the absence of strong latitudinal gradients in demographic attributes fails to support the hypothesis that differential survival/predation is responsible for the regional differences in numerical trends.

Behavioural responses of lynx to declining snowshoe hare abundance

1985 ◽  
Vol 63 (12) ◽  
pp. 2817-2824 ◽  
Author(s):  
Richard M. P. Ward ◽  
Charles J. Krebs
Keyword(s):  
Home Range Size ◽  
High Rate ◽  
Snowshoe Hare ◽  
Home Ranges ◽  
Lynx Lynx ◽  
Lynx Canadensis ◽  
Long Distance ◽  
Behavioural Responses ◽  
Straight Line ◽  
Daily Travel

The behavioural responses of lynx (Lynx canadensis) to declines in snowshoe hare (Lepus americanus) abundance were examined in the southwestern Yukon. Between April 1982 and June 1984, 11 lynx were radio tagged and monitored in and near the Kluane Game Sanctuary. Lynx home range size increased from 13.2 to 39.2 km2 concurrent with a decline in snowshoe hare abundance from 14.7 to 0.2 hares/ha. Below about 0.5 hares/ha, several lynx abandoned their home ranges and became nomadic, although they remained within the general study area. Lynx concentrated their foraging efforts in areas of relatively high snowshoe hare abundance and abandoned these areas after hares declined. Straight-line daily travel distance remained constant at 2.2−2.7 km/day above 1.0 hare/ha. Below 1.0 hares/ha, straight-line daily travel distances increased rapidly, reaching 5.5 km/day at 0.2 hares/ha. Three of seven radio-tagged lynx dispersed 250 km or more from the study area during the 1982 period of rapid hare decline. No similar long-distance emigrations were recorded after hare densities stabilized at less than 1.0 hares/ha. Trapping mortality was responsible for the loss of seven of nine radio-tagged lynx that travelled outside the game sanctuary. One lynx probably starved during the winter or spring of 1984. The high rate of trapping mortality outside the game sanctuary suggests that refugia in wilderness areas are important in maintaining lynx populations during periods of low recruitment.

The ecology of the lynx (Lynx canadensis) on Cape Breton Island

1983 ◽  
Vol 61 (4) ◽  
pp. 770-786 ◽  
Author(s):  
G. R. Parker ◽  
J. W. Maxwell ◽  
L. D. Morton ◽  
G. E. J. Smith
Keyword(s):  
Limited Range ◽  
Forest Harvesting ◽  
Snowshoe Hare ◽  
Home Ranges ◽  
Lynx Lynx ◽  
Lynx Canadensis ◽  
Cape Breton Island ◽  
Cape Breton ◽  
Hunting Success ◽  
Main Component

Recruitment of lynx (Lynx canadensis) on Cape Breton Island declined from 1977–1978 through 1979–1980 concurrent with a decrease in snowshoe hare (Lepus americanus) densities. Suppressed recruitment resulted from a decline in pregnancy rates, especially in the yearling cohort, and increased mortality of kits during the first 6 months of life. Snowshoe hare was the main component in the diet of lynx during both winter and summer. Lynx rarely travelled together except for females with kits. Hunting success (percent successful chases) increased wth group size. Overall hunting success increased through the winter. Winter kill rates averaged one hare per lynx per 24 h. Home ranges of adults were larger in summer (25–32 km2) than in winter (12–18 km2). Daily cruising distances (kilometres per 24 h) were greater in summer (~9 km) than in winter (~8 km). Although lynx used all habitats within their home ranges, they selected for the advanced successional habitat (~20 years after cutting) both winter and summer. Mature conifer habitat was used more in summer than in winter. The short-term impact of extensive forest harvesting within the limited range of lynx on the highlands of Cape Breton Island is uncertain; in the long-term it should prove beneficial by increasing the availability of preferred advanced successional habitat. Harvesting of lynx should be closely controlled, especially during periods of reduced densities of snowshoe hares and suppressed recruitment of lynx.

scholarly journals The enigma of the 10-year wildlife population cycle solved? Evidence that the periodicity and regularity of the cycle are driven by a lunar zeitgeber

2015 ◽  
Vol 128 (4) ◽  
pp. 327 ◽  
Author(s):  
Herbert L. Archibald
Keyword(s):  
Population Cycles ◽  
Amplitude Distribution ◽  
Ultraviolet B ◽  
Population Cycle ◽  
Snowshoe Hare ◽  
Lynx Lynx ◽  
Half Cycle ◽  
Ruffed Grouse ◽  
Lynx Canadensis ◽  
Wildlife Population

Despite nearly 100 years of research, the periodicity and regularity of the 10-year wildlife population cycle remain an enigma. This paper presents the hypothesis that the 9.3-year nodal half-cycle of the moon is the zeitgeber (“time-giver”) of the 10-year wildlife population cycle. The period of the population cycles of the Snowshoe Hare (Lepus americanus) and Ruffed Grouse (Bonasa umbellus) is close to 9.3 years. These wildlife cycles have stayed closely in phase with the 9.3-year nodal half-cycle for 150 years. Population density of the Snowshoe Hare and Ruffed Grouse is inversely related to a 9.3-year cycle of the moon's tidal force. There is also a 9.3-year cycle of “nights without darkness” at the equinoxes, in which the full moon rises before sunset and sets after sunrise the following morning in certain years. Snowshoe Hare and Ruffed Grouse cycles are positively correlated with this phenomenon. The nodal cycle provides explanations for the key features of the 10-year wildlife cycle: regularity, periodicity, amplitude, distribution, and synchrony. Population models based solely on the nodal cycle account for 62% of the variation in the Canada Lynx (Lynx canadensis) cycle and 37% in the Ruffed Grouse cycle. The mechanism(s) by which herbivore cycles might be entrained by the lunar nodal cycle could involve a cyclic effect on factors including predation, stress, photoperiod, phenology, temperature, cloudiness, ultraviolet B radiation, cosmic rays, and food plant quality.

Winter habitat selection by lynx and coyotes in relation to snowshoe hare abundance

1994 ◽  
Vol 72 (8) ◽  
pp. 1444-1451 ◽  
Author(s):  
Dennis L. Murray ◽  
Stan Boutin ◽  
Mark O'Donoghue
Keyword(s):  
Habitat Selection ◽  
Picea Glauca ◽  
Load Ratio ◽  
Snowshoe Hare ◽  
Lynx Lynx ◽  
Lynx Canadensis ◽  
Winter Habitat ◽  
Predator Species ◽  
Hunting Success ◽  
Snow Conditions

We examined the relationship between winter habitat selection among lynx (Lynx canadensis) and coyotes (Canis latrans) and relative snowshoe hare (Lepus americanus) abundance by tracking in snow during three winters. Hare numbers were higher in dense spruce (Picea glauca) than in other habitats in 1987–1988, and both predator species selected that habitat in that year. In 1988–1989, hare distribution was similar among habitats, and both predators used spruce habitats relative to their availability. In 1989–1990, hare numbers were also similar among habitats, and lynx used spruce habitats according to availability, whereas coyotes selected dense spruce. Hares were the main prey of both species, and the distribution of hares chased and killed by lynx was similar to that predicted by habitat use. Lynx hunting success was also similar among habitats. In comparison, coyotes chased and killed more hares than expected and had higher hunting success in dense spruce. Snow was shallower and harder in all spruce habitats used by coyotes than in those travelled by lynx. This suggests that coyotes were more selective of snow conditions than lynx, probably as a result of their high foot-load (ratio of body mass to foot area) relative to that of hares. Coyotes scavenged more often than lynx, but neither species seemed to select habitats on the basis of carcass availability. We concluded that high hare densities influenced selection of dense spruce by both species in 1987–1988, and that coyotes may also have chosen habitats on the basis of hunting success and snow conditions.

Mammal population cycles: evidence for intrinsic differences during snowshoe hare cycles

2003 ◽  
Vol 81 (2) ◽  
pp. 216-220 ◽  
Author(s):  
A R.E Sinclair ◽  
Dennis Chitty ◽  
Carol I Stefan ◽  
Charles J Krebs
Keyword(s):  
Reproductive Output ◽  
Population Cycles ◽  
Food Shortage ◽  
Population Cycle ◽  
Snowshoe Hare ◽  
Population Densities ◽  
Northern Latitudes ◽  
Snowshoe Hares ◽  
Reproductive Rates ◽  
High Phase

Some mammals in high northern latitudes show regular population cycles. In snowshoe hares (Lepus americanus), these occur every 9–10 years. One hypothesis proposes extrinsic causes such as food shortage or predation. The other proposes intrinsic causes through different morphs that alternate between different phases of the cycle. The morphs should differ in behaviour or physiology. This hypothesis predicts that animal lineages bred from high and low phases of the population cycle should differ in reproduction and survivorship. In a 16-year breeding program, lineages of purebred high-phase female hares had reduced reproductive rates relative to those of purebred low-phase females, resulting in extinction of high-phase lineages. Reproductive output declined with age in high- but not low-phase animals. These lineages also differed in longevity and senescence. These results are consistent with the intrinsic hypothesis and suggest a mechanism for alternating population densities that could work synergistically with extrinsic causes like predation and food shortage.

scholarly journals Experts correctly describe demography associated with historical decline of the endangered Indiana bat, but not recent period of stationarity

2017 ◽  
Author(s):  
Wayne Thogmartin ◽  
Carol Sanders-Reed ◽  
Jennifer Szymanski ◽  
Lori Pruitt ◽  
Michael Runge
Keyword(s):  
Population Decline ◽  
Survival Rates ◽  
Clear Understanding ◽  
Myotis Sodalis ◽  
Indiana Bat ◽  
White Nose Syndrome ◽  
Demographic Behavior ◽  
Pup Survival ◽  
Survival And Reproduction ◽  
Reproductive Rates

Demographic characteristics of bats are often insufficiently described for modeling populations. In data poor situations, experts are often relied upon for characterizing ecological systems. In concert with the development of a matrix model describing Indiana bat (Myotis sodalis) demography, we elicited estimates for parameterizing this model from 12 experts. We conducted this elicitation in two stages, requesting expert values for 12 demographic rates. These rates were adult and juvenile seasonal (winter, summer, fall) survival rates, pup survival in fall, and propensity and success at breeding. Experts were most in agreement about adult fall survival (3% Coefficient of Variation) and least in agreement about propensity of juveniles to breed (37% CV). The experts showed greater concordance for adult ( mean CV, adult = 6.2%) than for juvenile parameters ( mean CV, juvenile = 16.4%), and slightly more agreement for survival (mean CV, survival = 9.8%) compared to reproductive rates ( mean CV, reproduction = 15.1%). However, survival and reproduction were negatively and positively biased, respectively, relative to a stationary dynamic. Despite the species exhibiting near stationary dynamics for two decades prior to the onset of a potential extinction-causing agent, white-nose syndrome, expert estimates indicated a population decline of -11% per year (95% CI = -2%, -20%); quasi-extinction was predicted within a century ( mean = 61 years to QE, range = 32, 97) by 10 of the 12 experts. Were we to use these expert estimates in our modeling efforts, we would have errantly trained our models to a rapidly declining demography asymptomatic of recent demographic behavior. While experts are sometimes the only source of information, a clear understanding of the temporal and spatial context of the information being elicited is necessary to guard against wayward predictions.

scholarly journals Spatio-temporal responses of Canada lynx (Lynx canadensis) to silvicultural treatments in the Northern Rockies, U.S.

2018 ◽  
Vol 422 ◽  
pp. 114-124 ◽  
Author(s):  
Joseph D. Holbrook ◽  
John R. Squires ◽  
Barry Bollenbacher ◽  
Russ Graham ◽  
Lucretia E. Olson ◽  
...  
Keyword(s):  
Lynx Lynx ◽  
Lynx Canadensis ◽  
Canada Lynx ◽  
Silvicultural Treatments ◽  
Northern Rockies ◽  
Spatio Temporal
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