William D. Wishart's research while affiliated with University of Alberta and other places

Publications (14)

Article
Full-text available
Trophy hunting is a management goal for many populations of ungulates and has important implications for conservation because of the economic value of trophy males. To determine whether population density affected horn growth of males, a marked population of bighorn sheep (ovis canadensis) in Alberta, Canada, was studied for 27 years. For the first...
Article
Full-text available
In ungulates, body mass is often positively correlated with juvenile survival, but little is known of whether body mass affects survival of other age-classes. We studied two marked populations of bighorn sheep (Ovis canadensis) in Alberta, Canada, to determine if body mass affected the survival of different sex –age classes. Chest girth at weaning...
Article
Longitudinal studies of survival are valuable because age-specific survival affects population dynamics and the evolution of several life history traits. We used capture-mark-recapture models to assess the relationship between survival and sex, age, population, year of study, disease, winter weather, and population density in two populations of big...
Article
Full-text available
Individually marked bighorn sheep (Ovis canadensis) were monitored to determine how seasonal and lifetime changes in mass affected the development of sexual dimorphism, and to what extent mass at a given age could predict mass of the same sheep at a later age. We trapped sheep from late May to early October each year from 1971 to 1985 in a populati...
Article
Full-text available
We investigated the life history consequences of age at primiparity in two marked populations of bighorn sheep (Ovis canadensis), studied for 19 and 12 yr. Some ewes first lambed at 2 yr of age, others at 3 or 4 yr. Lambs of 2-yr-old ewes were smaller and less viable than lambs of older ewes. Lactation at 2 yr did not affect survival to 3 yr, but i...
Article
Full-text available
Theories of parental investment and parent-offspring conflict assume that investment involves a cost to the parent and a benefit to the offspring, but for herbivorous mammals, behavioral and nutritional weaning are gradual processes that are difficult to define, and little is known about the consequences of individual variation during weaning. To s...
Article
Full-text available
The factors affecting variation in age at first reproduction of bighorn ewes (Ovis canadensis) were investigated in two marked populations in Alberta. One population was studied for 20 years, the other for 11 years. As yearlings, females that lactated at 2 years of age were on average heavier and larger, and had longer horns than females that did n...
Article
Full-text available
We wanted to test whether ewe hunting would cause a decline in population size or in trophy ram production, and whether a reduction in ewe density would increase the size of ram horns. Thus, we examined the consequences of a bighorn sheep (Ovis canadensis) ewe hunting season through an experimental manipulation of an isolated population in Alberta,...
Article
Full-text available
Selenium levels and glutathione peroxidase (GSH-Px) activity were determined in the blood of wild and captive herds of bighorn sheep (Ovis canadensis), as well as in one wild mountain goat (Oreamnos americanus) herd. No significant relationship was established between blood selenium and GSH-Px activity for individual herds of bighorns, but when all...
Article
Twelve free-ranging Rocky Mountain bighorn lambs (Ovis canadensis canadensis), each exposed experimentally to 125-1,000 infective third-stage larvae of Protostrongylus stilesi and P. rushi, shed significantly more first-stage larvae in their feces than did control lambs, but showed no clinical signs of illness and had equivalent summer and overwint...
Article
Living specimens of 15 species of terrestrial gastropods (14 snails and 1 slug) were collected on a series of plots located in a variety of habitats associated with a winter range of bighorn sheep (Ovis canadensis) in southwestern Alberta. Four species of snails (Vertigo gouldi, Discus cronkhitei, Vitrina alaskana, and Euconulus fulvus) constituted...

Citations

... Another general rule is that the male survival should be lower and more variable than female survival (Toïgo and Gaillard 2003) in large iteroparous and highly dimorphic ungulates (sexual size dimorphism SSD !20%; Ruckstuhl and Neuhaus 2002). This is due to contrasted lifehistory tactics between sexes (e.g., Clutton-Brock et al. 1982;Jorgenson et al. 1997) which lead males to be more sensitive to food limitation than females (Toïgo and Gaillard 2003). Mouflon with their marked SSD (e.g., Table 1), and the limiting resources conditions experienced by the Caroux-Espinouse population (Garel et al. 2007 and illustrates possible costs caused by sexual selection in males. ...
... Horn length is highly genetically correlated across the sexes [15], thus females with long horns are expected to be both progeny and parents of longer-horned, typically higher-fitness males [10]. Jorgenson et al. [19] found that female yearlings with larger horns were more likely to have offspring earlier in life, however, that study did not control for a possible effect of body mass, which is also associated with age at primiparity [20,21]. Thus far, the relationships between horn size, body mass and age at primiparity have not been disentangled. ...
... Range-wide in mesic habitats Alberta, Canada Yes [163] California No [164] Colorado No [27] Colorado Yes [146] [165] Montana Yes [113] [166] Montana No [148] [167] Nevada No [168] Oregon No [149] Utah No [169] Wyoming Unclear 2 [118] [122] [170] Lungworm (Muellerius capillaris) Localized Montana No [128] South Dakota No [171] Bacteria Pasteurellaceae Range-wide Alberta Yes [151] Arizona No [172] California No [164] Colorado No [27] Colorado Yes [19] Hells Canyon (Washington, Idaho) Yes [18] [152] [173] Idaho No [174] Montana Yes [17] Montana No [128] Nevada No (endemic) [175] Oregon Yes [176] [177] Wyoming Yes [43] Arcanobacterium (Corynebacterium) Presumed range-wide Colorado Yes [157] pyogenes Montana Yes [113] [166] Mycoplasma Uncertain Arizona Yes [178] Hells Canyon Yes [18] [179] Chlamydophila (Chlamydia) Psittaci Uncertain Wyoming Yes [180] Veterinary Medicine International ...
... This suggests that under poor nutritional conditions generated by high population density, resource allocation to body mass is prioritized possibly at the expense of horn growth. These results confirm the key role of body mass for reproduction in these capital breeder species (Gaillard et al. 2000, Bonenfant et al. 2009b, and also corroborate earlier results by Jorgenson et al. (1998) and Festa-Bianchet et al. (2004) who showed that the effects of density on horn length and body mass mostly affect young age classes. The absence of statistically significant differences in slope may reflect a lack of statistical power. ...
... Mass could better represent morphological and physiological constraints to the studied behaviours than age (P erez- Barbería et al., 2008). Nevertheless, mass is strongly correlated with size and age (Festa-Bianchet et al., 1996) and mass effects should largely reflect age effects. To avoid problems with multicollinearity, we therefore did not include age. ...
... For example, Canada lynx (Lynx canadensis) can reproduce earlier when prey density is higher (Reynolds et al. 2017). Additionally, in many mammals such as moose (Markussen et al. 2018) and bighorn sheep (Festa-Bianchet et al. 1995), females with a higher body mass are able to reach primiparity sooner. Warmer climate and weather have also been shown to decrease age at primiparity in other taxa. ...
... Because we did not capture and equip cubs with radio collars in our study, the fate of orphaned cubs is typically unknown. Some orphaned cubs have been documented to survive , but considering that orphaned offspring can show reduced growth and future survival prospects (Festa-Bianchet et al., 1994), their contribution to the population as adults might be limited (Zedrosser et al., 2013). Third, we assumed males and females as similarly vulnerable to hunting in our calculations of hunting mortality. ...
... However, it is difficult to infer a seasonal pattern for this species because it has a life span of less than one year (Faberi et al. 2006;Mohamed and Ali 2011) and lays eggs continuously after maturity (Chichester and Getz 1973;Jordaens et al. 2006). All life stages of D. laeve can be found throughout the year, including winter, suggesting overlapping generations (Taylor 1907;Getz 1959;Quick 1960;Chichester and Getz 1973;Boag and Wishart 1982;Jordaens et al. 2006). Most D. laeve we caught in September were extremely small, indicating recent hatching. ...
... [32] from the main species range. Monitoring started in 1971 [33] and is ongoing. The Ram Mountain population was historically subjected to trophy hunting of males based on horn size [27]. ...
... Body mass in all sex-and age-classes increased during the trapping season (Jorgenson and Wishart 1984). For most analyses we wanted to compare the body mass of different groups of ewes at the beginning and end of summer. ...