Male Coyotes Research Articles

Variable duration of reproductive suppression in male coyotes (Canis latrans) treated with a high dose of the gonadotrophin-releasing hormone agonist deslorelin.

Effective and humane management strategies for coyotes (Canis latrans) remain elusive. We hypothesised that exposure to a high dose of a gonadotrophin-releasing hormone (GnRH) agonist would cause prolonged suppression of the reproductive axis. Two groups of male coyotes were administered 47mg deslorelin in the form of either five 9.4-mg controlled-release Suprelorin (Peptech Animal Health, Macquarie Park NSW, Australia) implants (n=3) or 10 4.7-mg implants (n=5). In the first group, deslorelin suppressed plasma LH, testosterone and testes volume in two of three coyotes for three breeding seasons. In the second group, two of five deslorelin-treated coyotes had no sperm production after 1 year and plasma LH, FSH, testosterone and testes volume were suppressed. Although plasma gonadotropins and testosterone were suppressed in three treated coyotes in group two, testes volume and sperm production were evident. Because the duration of suppression differed among individual coyotes, we further hypothesised that a variation in deslorelin release underlay the variability. To test this, we analysed in vivo plasma profiles of deslorelin concentrations. These profiles suggested that deslorelin concentrations >100 pg mL-1 are required to maintain suppression in male coyotes. For field implementation, the development of an implant capable of releasing deslorelin for the life of the coyote is necessary.

Spatial Genetic and Body-Size Trends in Atlantic CanadaCanis latrans(Coyote) Populations

Abstract Eastern Canis latrans (Coyote) dispersed into northeastern North America during the last century and into Nova Scotia in the 1970s. En route, Coyotes hybridized extensively with C. lycaon (Eastern Wolf). Coyote populations in northeastern North America contain mitochondrial and nuclear DNA characteristics of both species. In samples collected from Nova Scotia, Prince Edward Island, New Brunswick, and Newfoundland, we found mitochondrial DNA haplotypes characteristic of Coyote and/or Eastern Wolf with decreasing haplotype diversity consistent with sequential founder events/bottlenecks moving from west to east generally and on islands. Principal components analysis of a suite of morphological characters indicated that male eastern Coyotes from Nova Scotia with Eastern Wolf mitochondrial DNA are significantly larger than male eastern Coyotes from the same region with Coyote mitochondrial DNA.

CONTRACEPTION HAS GONE TO THE COYOTES (CANIS LATRANS)

Coyotes (Canis latrans) are predators of livestock. Current management programs, primarily lethal control, are ineffective for long-term management of predation. Controlling reproduction of coyotes may reduce depredations if territory fidelity is maintained by breeding pairs. Surgical sterilization is successful in altering predatory behaviors of coyotes but may provide a challenge for field implementation. An alternative approach is the development of a one-time non-transferable chemical contraceptive. This research is investigating the efficacy of a single high dose treatment of a sustained release gonadotropin-releasing hormone agonist, deslorelin, on coyotes as a long term contraceptive. Male coyotes were administered 47 mg deslorelin subcutaneously. Preliminary data show full suppression of the reproductive axis for over 12 mo as indicated by complete absence of sperm.

Seasonal variation in serum testosterone, testicular volume, and semen characteristics in the coyote (Canis latrans)

The coyote is a seasonally breeding mammal, with most copulations occurring between December and April (depending on location). The objective of this study was to characterize seasonal changes in serum testosterone concentrations, testicular volume, and ejaculate quantity and quality in captive male coyotes. There were seasonal differences in testicular volume, with the greatest volume (20.2+/-5.4cm2), mean+/-S.E.M.) in February, corresponding with peak breeding season. Circulating serum testosterone concentrations peaked (3.31+/-0.9 ng/mL) during January and were positively correlated (P< or =0.001, r=0.413) with testicular volume. Ejaculate volume (1.67+/-0.4 mL) and sperm concentration (549.2 x 10(6)+/-297.7 spermatozoa/mL) both peaked during January and February, consistent with the height of the breeding season. Ejaculate volume and sperm concentrations were positively correlated with testicular size (r=0.679, P< or =0.001 and r=0.499, P< or =0.001, respectively) and with serum testosterone concentrations (r=0.368, P< or =0.01 and r=0.208, P< or =0.05). Progressively motile, viable, and morphologically normal spermatozoa fluctuated seasonally, peaked (90.4+/-4.5, 84.8+/-4.1, and 87.9+/-2.9%) during the breeding season, and then subsequently declined (period of aspermatogenesis). All three of these end points were positively correlated with testicular size (r=0.589, P< or =0.001; r=0.586, P< or =0.001; and r=0.469; P< or =0.001) and serum testosterone (r=0.167, P< or =0.05; r=0.190, P< or =0.05; and r=0.221, P< or =0.01). In conclusion, there were intricate relationships among testosterone concentrations, testicular volume, and the production of both functionally intact and morphologically normal spermatozoa.

Effects of Sarcoptic Mange on Coyotes at Wind Cave National Park

Abstract: Home‐range size and population abundance indices of coyotes (Canis latrans) have not been documented in Wind Cave National Park, South Dakota, USA. In 2003 and 2004, we captured a total of 26 coyotes and radiocollared 22 adults (12 F, 10 M). In 2003 and 2004, 2 of 17 (12%) and 5 of 9 (56%) coyotes, respectively, were infected with sarcoptic mange (Sarcoptes scabiei) at the time of capture. Thus, objectives were modified to document effects of the mange epizootic on the coyote population. In 2003, home‐range (adaptive‐kernel) sizes for male coyotes with mange and those considered healthy were 8.26 ± 1.63 (SE) km2 and 9.67 ± 2.80 km2, respectively. In 2004, home‐range sizes for those male coyotes with and without mange were 22.69 ± 9.06 km2 and 12.51 ± 2.73 km2, respectively. Male home‐range size did not differ between years (P = 0.14) or by status (with or without mange; P = 0.84). Survival of collared coyotes was 60% at the end of 2003. Results from fecal line transects, an index of relative abundance, indicated that the coyote population decreased by 48% from 2003 to 2004. Continued monitoring of sarcoptic mange epizootics will enable managers to assess the effects of mange on coyote populations.

A Comparison of Body Mass of Canis latrans (Coyotes) Between Eastern and Western North America

Abstract Contrary to previous literature concluding that body size of Canis latrans (coyotes) does not increase in North America with decreasing longitude, this study presents data from different regions and concludes that northeastern coyotes are the largest extant version of coyote. Male coyotes from northeastern North America (16.4 ± 1.5 [SD] kg, range = 14.2–20.4) were heavier than females from the northeast (14.7 ± 1.6 kg, range = 11.9–17.9) and were also heavier than male (10.6 ± 1.0 kg, range = 8.8–12.0) and female coyotes (12.1 ± 1.1 kg, range = 10.5–14.1) from outside of the northeast. Female coyotes from northeastern North America were heavier than all male and female western coyotes. Longitude was significantly correlated in both male (r = − 0.786, P < 0.0001) and female (r = − 0.769, P < 0.0001) body mass, whereas there was less of a correlation for latitude and body mass for males (r = 0.355, P = 0.043) and females (r = 0.364, P = 0.044). Sixty-two percent (P < 0.0001) and 59% (P < 0.0001) of...

Salivary DNA Evidence Convicts Breeding Male Coyotes of Killing Sheep

Resolving conflicts between predators and livestock producers depends on obtaining reliable information about the predators that kill livestock. We used salivary DNA obtained from attack wounds on domestic sheep carcasses to identify the species of predator responsible for the kill, as well as the sex and individual identity of coyotes (Canis latrans) that killed sheep. Coyotes killed 36 of 37 depredated sheep. Breeding pairs whose territories overlapped sheep grazing areas were the primary predators on domestic sheep, and only breeding pairs killed multiple sheep. Breeding males, acting alone or with their mate, were involved in 21 of 25 kills. Breeding females participated in 13 kills, but only 1 breeding female killed sheep on her own. Transient females did not kill sheep, and both kills by transient males occurred in territories with a breeding vacancy. Our results suggest that predator control should be targeted at breeding male coyotes. Salivary DNA is a potentially powerful means of both investigating predation patterns and evaluating the effectiveness of control at targeting individuals that kill livestock.

Relaxin as a diagnostic tool for pregnancy in the coyote ( Canis latrans)

The diagnosis of pregnancy in the domestic dog ( Canis familiaris) often employs specialized equipment, experienced staff, and the cooperation of the bitch. These procedures can be challenging when the subject is a wild canid, particularly in a field setting. In addition, reproductive hormone assays are unreliable as a diagnostic tool because the estrous profiles of pregnant and pseudopregnant canines are similar. However, research has demonstrated that the hormone relaxin can be detected in maternal blood after embryonic implantation, but remains negligible in non-pregnant females. We investigated the use of relaxin as a diagnostic marker of pregnancy in the coyote ( C. latrans). A commercially available canine relaxin enzyme immunoassay (ReproCHEK™) was used to test plasma collected from 124 female coyotes over four consecutive breeding seasons. Mating activities of the captive females were observed; then peripheral blood samples were collected at intervals throughout pregnancy, as well as after parturition. Results demonstrated that relaxin could be detected in the plasma of pregnant coyotes after 28 days of gestation, and in some cases as early as 23 days, while non-pregnant females and male coyotes consistently tested negative. Relaxin also remained detectable in the plasma of the majority of females tested 10–12 weeks after parturition. This qualitative assay for relaxin proved to be a reliable diagnostic tool for pregnancy in the coyote. In addition, blood sampling was relatively easy, could be accomplished with minimal handling, and did not require sedation or anesthesia.

Total energy budget and prey requirements of free-ranging coyotes in the Great Basin desert of the western United States

Estimates of energetic demands for carnivore species can be valuable for estimating their annual prey requirements and thus, their potential impact on prey populations. This is the case for the coyote ( Canis latrans) which has a ubiquitous distribution and preys on a wide variety of wild and domestic prey species. We took data on daily activity of coyotes and with standard energy models, estimated the daily field metabolic rate (FMR) of adult male and female coyotes in the Great Basin desert of the western United States. We then calculated the total annual energy demand and from this, extrapolated annual prey needs for lagomorph and rodent-sized prey. Daily FMR of male coyotes in the Great Basin desert averaged 1170.1 kcal±29.1, S.E. (n=11) and was significantly higher than 988.6 kcal±44.3 (n=8) for females ( p=0.002). The highest reproductive cost for females was lactation (1441.1 kcal/day above FMR). Males and females need to consume 192 and 162 lagomorphs, or 3681 and 3110 rodents/year, respectively. For reproduction, females should consume 37 more lagomorphs or 700 more rodents per year. We concluded that preference for lagomorphs by coyotes reflects the most reasonable energy return on their hunting investment.

Widespread occurrence of a domestic dog mitochondrial DNA haplotype in southeastern US coyotes.

Sequence analysis of the mitochondrial DNA control region from 112 southeastern US coyotes (Canis latrans) revealed 12 individuals with a haplotype closely related to those in domestic dogs. Phylogenetic analyses grouped this new haplotype in the dog/grey wolf (Canis familiaris/Canis lupus) clade with 98% bootstrap support. These results demonstrate that a male coyote hybridized with a female dog, and female hybrid offspring successfully integrated into the coyote population. The widespread distribution of this haplotype from Florida to West Virginia suggests that the hybridization event occurred long ago before the southeastern USA was colonized by coyotes. However, it could have occurred in the southeastern USA before the main front of coyotes arrived in the area between male coyotes released for sport and a local domestic dog. The introgression of domestic dog genes into the southeastern coyote population does not appear to have substantially affected the coyote's genetic, morphological, or behavioural integrity. However, our results suggest that, contrary to previous reports, hybridization can occur between domestic and wild canids, even when the latter is relatively abundant. Therefore, hybridization may be a greater threat to the persistence of wild canid populations than previously thought.

FACULTATIVE DYAD FORMATION IN ADULT MALE COYOTES

As part of a larger study, we investigated the intensity and duration of association between 2 adult male coyotes (Canis latrans) in an agrarian landscape in west-central Indiana. Home-range size and overlap and the intensity of association varied with time. Home-range sizes averaged 7.9 ± 1.1 (SE) and 11.8 ± 0.9 km2, and spatial overlap was substantial. Activity patterns and habitat preferences were similar for the coyotes whether together or apart, and there was no evidence of temporal or spatial avoidance. The 2 males were together most frequently during the pup-rearing and dispersal seasons, suggesting provisioning of pups and vigilance at diurnal resting sites as possible mechanisms for the dyad formation.

Facultative Dyad Formation in Adult Male Coyotes

Facultative Dyad Formation in Adult Male Coyotes

Does Paternal Care of Pups Benefit Breeding Female Coyotes?

Post-partum care of offspring by male parents (paternal care), although rare among mammals generally, occurs commonly within the Carnivora, Primates, and Rodentia (Kleiman, 1977). Whereas lactation constrains female mammals to care for young, males are not similarly constrained (Trivers, 1972). Therefore, occurrence of paternal care in certain mammalian taxa suggests either strong benefits to males (male-choice hypothesis-Trivers, 1972; Gubernick et al., 1993) or benefits to females of sufficient magnitude to promote sexual selection for this trait in males (femalechoice hypothesis-Orians, 1969; Wittenberger and Tilson, 1980). In the former case, paternal care primarily should enhance current reproductive success (i.e., of both sexes), whereas in the latter case, paternal care primarily should affect future reproductive success of the female (i.e., through increased survival or future fecundity). Among mammalian families, paternal care is most pronounced in the Canidae, in which males typically share in all pup-rearing behaviors except nursing (e.g., Kleiman, 1977). The relative benefits of these contributions to current and future reproductive success of females (or of males) have not been empirically investigated in this family. Benefits of paternal care to current and future reproductive success of mates can be investigated by observing consequences to the female of male removal (Mock and Fujioka, .1990). In the absence of paternal care, one of 3 possible strategies for the female canid is predicted from life-history theory (Williams, 1966; Stearns, 1992). First, the female could abandon or kill her litter, thereby sacrificing all current reproductive potential to maximize future reproductive potential (Tait, 1980). Second, she could provide the same amount of care as she would have in the presence of paternal care, presumably sacrificing some of her current reproductive potential, but with no change in her future reproductive potential. Third, she could provide a greater than normal amount of care to compensate for the absence of paternal care, thus sacrificing no current reproductive potential, but reducing her future reproductive potential. The first strategy is most consistent with the male-choice hypothesis and the third strategy is most consistent with the female-choice hypothesis. We used radiotelemetry and observations from a natural experiment of removals of male coyotes (Canis latrans) to investigate these strategies. Coyotes in our study area were routinely killed (regardless of whether they were radiocollared) by control personnel to reduce predation on domestic sheep (Sacks et al., 1999); this resulted in removal during pup-rearing of several paternal males and eventually some of their mates and pups, which were provided to us for post-mortem examination. We compared females with mates present to females

Resource use by unexploited sympatric bobcats and coyotes in Oregon

Unexploited populations of bobcats (Felis rufus) and coyotes (Canis latrans) were studied in the Elliott State Forest, Douglas and Coos counties, Oregon, from September 1981 to July 1982. A total of 633 radio locations of six bobcats and five coyotes were used to determine home ranges, activity, and habitat-use patterns. Twenty-five prey items were identified in bobcat and coyote scats. Diets of the two species were similar (overlap values were greater than 0.92 for all seasons). Mountain beaver (Aplodontia rufa) remains occurred in over 70% of the scats from both species. Home ranges for radio-collared animals averaged 14 km2 for male coyotes, 12 km2 for female coyotes, 11 km2 for one male bobcat, and 2 km2 for female bobcats. Bobcat and coyote home ranges overlapped in time as well as space. Radio-collared bobcats were detected on occasion within the same clear-cut sites concurrently with radio-collared coyotes, and daily activity patterns were nearly identical between the two predators. Bobcats and coyotes used open areas during nightly hunting activities and retired to forested areas during the day. Coyotes used grassy, more open clearings whereas bobcats favored brushy sites.

Antifertility effect of busulfan and DL-6-(N-2-pipecolinomethyl)-5-hydroxy-indane maleate (PMHI) in coyotes ( [formula omitted][formula omitted

Antifertility effects of busulfan were evaluated using adult coyotes. In addition, antifertility effects of PMHI were evaluated in adult males. Adult males and females were alloted randomly to the following treatments: (1) untreated control, (2) a single oral dose of 3 mg busulfan/kg of body weight (BW) or (3) two oral doses of 3 mg busulfan/kg BW given nine days apart. The untreated males were used as controls in both experiments. Additional male coyotes were allotted randomly to PMHI treatments as follows: (1) a single oral dose of 2 mg PMHI/kg BW, or (2) two oral doses of 1 mg PMHI/kg BW given seven days apart. Blood samples were taken from females and serum analyzed for progesterone by radioimmunoassay. Males were hemicastrated (left testicle) 30 days after onset of treatment. The right testicle was removed 30 days later. Testes and epididymides were fixed in 10% buffered formalin and prepared for histologic examination. For females developing corpus luteum (CL), the maximum peak progesterone concentration for those given two doses of busulfan was less (P<0.05) than that for untreated controls and single-dose females (16.9, 22.4 and 26.3 ng/ml, respectively). The double treatment of busulfan prevented more females (4 of 10) from developing CL (P<0.08) than controls (0 of 7) or single-dose females (1 of 9). None of the busulfan-treated male coyotes had histologic evidence of spermatogenesis 60 days after the onset of treatment. The oral dose or doses of PMHI did not result in complete degeneration of seminiferous tubules. Busulfan given orally did not cause any adverse reactions, but orally administered PMHI often induced vomiting within 18 min after treatment. We conclude that busulfan is capable of affecting male and female reproductive parameters, but PMHI appears to have little effect on spermatogenesis in coyotes when given orally in a single- or a double-dose.

Electroejaculation of the coyote

Two electroejaculators were used to collect semen from 40 adult male coyotes. The most effective apparatus used a two-ring rectal probe and an AC voltage of 18 (Vrms) at 1000 Hz. With this ejaculator, 11 of 15 coyotes produced a satisfactory semen sample, which averaged 0.9 ml in volume and 70 million spermatozoa per ml.

Antitesticular activity of DL-6-(N-2-Pipecolinomethyl)-5-Hydroxy-Indane maleate (PMHI) in coyotes (canis latrans)

The ban on toxicants for coyote control has created a need for alternative control methods. Reproductive inhibitors may provide a means of maintaining coyote populations at levels where impact on live-stock is acceptable. Therefore, the effects of PMHI on testicular activity of coyotes were evaluated. Twelve mature, male coyotes were weighed and allotted randomly to 1 of 4 treatment groups: (1) controls, (2) 5, (3) 10, and (4) 20 mg PMHI/kg body weight (BW). PMHI was dissolved in 2 ml distilled water and ethanol (1:1) and administered as a single sc injection. All coyotes were observed for 1 hr after treatment and any adverse effects recorded. Fifteen days after treatment, a testicle and epididymis from each coyote was selected at random, ablated, weighed, fixed in formalin, and prepared for histologic examination. The remaining testicle was prepared similarly 30 days post-treatment. Data were analyzed by a balanced factorial in a split-plot arrangement. Unlike controls, coyotes given PMHI exhibited signs of nausea and diarrhea within 15 to 30 min, which subsided after 45 to 60 min. PMHI temporarily increased (P<.01) serum glutamic-pyruvate transaminase (SGPT) but did not alter other blood chemistry or hematologic values. PMHI reduced (P<.01) testicular weights (wet weights) from 10±1.0 g (controls) to 6.3±0.2 g after 5 mg, 4.4±0.2 g after 10 mg, and 6.0±0.5 g after 20 mg/kg BW. Testicular weights were not different among the 3 treatments of PMHI. Histological changes in seminiferous tubules were consistent with absence of spermatogenesis at 15 and 30 days after all treatment levels of PMHI. Only occasional intact spermatozoa were present in sections of epididymis at 15 and 30 days after PMHI treatment. We conclude that PMHI may cause infertility in the male coyote from 15 to at least 82 days after treatment without apparent chronic damage to vital organs.

Regional Weights of Kansas Coyotes

In order to obtain a representative statewide sample of Kansas coyote (Canis latrans) weights, spring scales were provided to selected coyote hunters, trappers, and furbuyers throughout the state. These cooperators were also provided with data forms and were asked to record the sex and weight (to the nearest pound) of all coyotes they collected. Weights were obtained from the period November through February in 1974-1975 and 1975-1976. Weightswere obtained from 307 coyotes in Comanche, Ellis, Finney, Grant, Hamilton, Norton, and Wichita Counties in western Kansas and from 289 coyotes in Cowley, Dickinson, Douglas, Franklin, Leavenworth, Montgomery/Nemaha, and Washington counties in eastern Kansas. results of the investigation are presented in Table 1. data were subdivided by sex and by region, using 98.5 degrees longitude as the division between the eastern and the western portions of the state. Student's t-tests (Snedecor and Cochran 1967) were used to test for significant differences between sexes and between regions. Since no coyotes were weighed before November, all were probably at or near their adult weight. In all cases, mean weights of male coyotes were greater than those of females (P <0.01). In addition, male and female coyotes collected east of 98.5 degrees longitude weighed more than their respective western Kansas counterparts (P C0.01) (Table 1). statewide mean weights for male (x = 28.9 pounds) and female (x = 24.1 pounds) coyotes collected in this study were less than the 30.7 and 26.0 pound means reported for male and female coyotes, respectively, by Gier (1968). However, 1888 of the 2062 coyotes (91.6 percent) collected by Gier came from east of 98.5 degrees longitude. mean weights reported by Gier (1968) are similar to our findings for eastern Kansas. observed differences in mean weights between eastern and western Kansas coyotes may be related to subspecific differences in coyotes within the state. Young and Jackson (1951) and Hall (1955) considered the southeastern coyote. Canis latrans frustror Woodhouse, to occupy the eastern-southeastern quarter of Kansas and the plains coyote, Canis 1. Iatrans Say, to occupy the remainder of the state. Our findings are consistent with the statement by Young and Jackson (1951:274) that, The subspecies frustror is the largest of the coyotes . . .' observed weight differences could also be related to differences in temperature or other environmental factors between the two areas.

ELECTROPHORETIC PROTEIN ANALYSIS IN THE CONDITIONED CAPTIVE WILD COYOTE, Canis latrans

Total protein, albumin and serum protein values were determined on 19 male and 14 female captive, vaccinated, wild coyotes. Male coyotes had significantly higher total protein, alpha 1 and alpha 2 globulin levels than female coyotes. Captive, wild coyotes had lower values for total protein, albumin and beta globulins, and higher values for alpha 2 and gamma globulins than similar values for laboratory dogs. Albumin values determined by bromcresol green were slightly higher than values derived by electrophoresis. This difference was non-significant.

Insensitivity of the coyote testis to orally administered cadmium

A study was conducted to evaluate cadmium as an oral antifertility agent in the coyote. Adult wild male coyotes were treated with cadmium chloride (CdCl 2) when testicular tissues were in both seasonally regressed and active states. One group of seven animals received individual oral doses of CdCl 2 at 12 mg/kg of body weight during the stage of complete testicular regression; another group similarly received 24 mg/kg. An additional group of six animals was used as untreated controls. Unilateral testicular ablations were carried out at 60, 120 and 240 days post-treatment. No histopathological changes were noted at either treatment level or at any testing period. Testicular tissue taken at the 240 day period revealed normal spermatogenesis. Testicular tissue was removed at 1, 8, 13, 21, and 30 days after the coyotes had received 24 mg/kg of CdCl 2 orally during the stage of active spermatogenesis. Histological examination of this tissue revealed no pathological changes.