Marked Adult Females Research Articles

The importance of individual variation in the alarm calls of Gunnison's prairie dogs

Gunnison's prairie dogs, Cynomys gunnisoni, frequently utter a repetitive series (a ‘bout’) of alarm calls (called ‘barks’) in response to a variety of terrestrial predators. Previous work has suggested that the structure of barks is finely tuned in ways that provide highly specific information about the identity of the predator. We re-evaluated these findings by presenting individually marked adult females with taxidermy mounts of three terrestrial predators of prairie dogs: a coyote, Canis latrans, a bobcat, Lynx rufus, and an American badger, Taxidea taxus, as well as one control stimulus (a cardboard box). Significant variation among individuals was evident from analyses of 10 measures associated with the general pattern of barking (e.g. latency to begin barking, bout duration, average number of barks/bout, overall bark rate, interbout interval) and also from eight structural features of individual barks (e.g. frequency and duration measures of the fundamental frequency band). When controlling for the identity of alarm callers, we found little evidence for differences in these same variables in response to different stimuli. We conclude that, like several other species of ground-dwelling squirrels, Gunnison's prairie dogs have an individually distinctive alarm call that does not differ for different predators. Our results conflict with earlier claims of extreme specificity in the alarm calls of Gunnison's prairie dogs.

Respiratory disease, behavior, and survival of mountain goat kids

ABSTRACTBacterial pneumonia is a threat to bighorn sheep (Ovis canadensis) populations. Bighorn sheep in the East Humboldt Mountain Range (EHR), Nevada, USA, experienced a pneumonia epizootic in 2009–2010. Testing of mountain goats (Oreamnos americanus) that were captured or found dead on this range during and after the epizootic detected bacteria commonly associated with bighorn sheep pneumonia die‐offs. Additionally, in years subsequent to the bighorn sheep epizootic, the mountain goat population had low kid:adult ratios, a common outcome for bighorn sheep populations that have experienced a pneumonia epizootic. We hypothesized that pneumonia was present and negatively affecting mountain goat kids in the EHR. From June–August 2013–2015, we attempted to observe mountain goat kids with marked adult females in the EHR at least once per week to document signs of respiratory disease; identify associations between respiratory disease, activity levels, and subsequent disappearance (i.e., death); and estimate weekly survival. Each time we observed a kid with a marked adult female, we recorded any signs of respiratory disease and collected behavior data that we fit to a 3‐state discrete hidden Markov model (HMM) to predict a kid's state (active vs. sedentary) and its probability of disappearing. We first observed clinical signs of respiratory disease in kids in late July–early August each summer. We observed 8 of 31 kids with marked adult females with signs of respiratory disease on 13 occasions. On 11 of these occasions, the HMM predicted that kids were in the sedentary state, which was associated with increased probability of subsequent death. We estimated overall probability of kid survival from June–August to be 0.19 (95% CI = 0.08–0.38), which was lower than has been reported in other mountain goat populations. We concluded that respiratory disease was present in the mountain goat kids in the EHR and negatively affected their activity levels and survival. Our results raise concerns about potential effects of pneumonia to mountain goat populations and the potential for disease transmission between mountain goats and bighorn sheep where the species are sympatric. © 2018 This article is a U.S. Government work and is in the public domain in the USA.

Estimating dispersal rates of Steller sea lion (Eumetopias jubatus) mother-pup pairs from a natal rookery using mark-resight data.

To monitor population trends of Steller sea lions (Eumetopias jubatus) in Alaska, newborn pups are counted during aerial surveys. These surveys are scheduled to occur after the majority of pups are born, but before pups begin to spend significant time in the water. Some studies have reported dispersal of mother-pup pairs away from breeding beaches during the pupping season (July), which may influence survey results. Using a multistate mark-recapture model with state uncertainty, we estimated the amount of dispersal during the pupping season based on observations of permanently marked sea lions. Research was conducted at land-based observation sites on Marmot Island, Alaska, between 2000 and 2013. Both marked adult females with dependent pups and marked pups were observed at two rookery beaches from May to July. Cumulative dispersal rates were minimal (< 1%) prior to the planned start of the aerial survey (23 June) and increased to 11.2% by the planned survey completion date (10 July). The increased cumulative dispersal rate during the remainder of the observation period (end of July) suggests potential bias in surveys that occur beyond 10 July, however surveys past this date are rare (< 10% between 1973 and 2016). As a result, movements of mother-pup pairs during the pupping season are not likely to influence aerial survey estimates.

Using Vaginal Implant Transmitters to Aid in Capture of Mule Deer Neonates

Abstract:Estimating survival of the offspring of marked female ungulates has proven difficult in free‐ranging populations yet could improve our understanding of factors that limit populations. We evaluated the feasibility and efficiency of capturing large samples (i.e., &gt;80/yr) of neonate mule deer(Odocoileus hemionus)exclusively from free‐ranging, marked adult females using vaginal implant transmitters (VITs,n= 154) and repeated locations of radiocollared females without VITs. We also evaluated the effectiveness of VITs, when used in conjunction with in utero fetal counts, for obtaining direct estimates of fetal survival. During 2003 and 2004, after we placed VIT batteries on a 12‐hour duty cycle to lower electronic failure rates, the proportion that shed ≤ 3 days prepartum or during parturition was 0.623 (SE = 0.0456), and the proportion of VITs shed only during parturition was 0.447 (SE = 0.0468). Our neonate capture success rate was 0.880 (SE = 0.0359) from females with VITs shed ≤ 3 days prepartum or during parturition and 0.307 (SE = 0.0235) from radiocollared females without VITs or whose implant failed to function properly. Using a combination of techniques, we captured 275 neonates and found 21 stillborns during 2002‐2004. We accounted for all fetuses at birth (i.e., live or stillborn) from 78 of the 147 females (0.531, SE = 0.0413) having winter fetal counts, and this rate was heavily dependent on VIT retention success. Deer that shed VITs prepartum were larger than deer that retained VITs to parturition, indicating a need to develop variable‐sized VITs that may be fitted individually to deer in the field. We demonstrated that direct estimates of fetal and neonatal survival may be obtained from previously marked female mule deer in free‐ranging populations, thus expanding opportunities for conducting field experiments. Survival estimates using VITs lacked bias that is typically associated with other neonate capture techniques. However, current vaginal implant failure rates and overall expense limit broad applicability of the technique.

FACTORS INFLUENCING MOVEMENT PROBABILITIES OF BIG BROWN BATS (EPTESICUS FUSCUS) IN BUILDINGS

We investigated movements of female big brown bats (Eptesicus fuscus) roosting in maternity colonies in buildings in Fort Collins, Colorado (USA), during the summers of 2002, 2003, and 2005. This behavior can be of public health concern where bats that may carry diseases (e.g., rabies) move among buildings occupied by people. We used passive integrated transponders (PIT tags) to mark individual bats and hoop PIT readers at emergence points to passively monitor the use of building roosts by marked adult females on a daily basis during the lactation phase of reproduction. Multi-strata models were used to examine movements among roosts in relation to ambient temperatures and ectoparasite loads. Our results suggest that high ambient temperatures influence movements. Numbers of mites (Steatonyssus occidentalis) did not appear to influence movements of female bats among building roosts. In an urban landscape, periods with unusually hot conditions are accompanied by shifting of bats to different buildings or segments of buildings, and this behavior may increase the potential for contact with people in settings where, in comparison to their more regularly used buildings, the bats may be more likely to be of public concern as nuisances or health risks.

Effects of Intrinsic and Extrinsic Factors on Survival of White-Winged Scoter (Melanitta Fusca Deglandi) Ducklings

AbstractIn waterfowl, offspring survival and the effects of extrinsic (i.e. weather, hatching date) and intrinsic (i.e. physical and nutritional traits of individual females and ducklings, brood sizes) factors on it are poorly understood. In 2000 and 2001, we estimated duckling and brood survival of White-winged Scoters (Melanitta fusca deglandi) at Redberry Lake, Saskatchewan, Canada, to 30 days of age to examine relationships between duckling survival and (1) hatch date, (2) initial brood size at hatch, (3) duckling size and body condition at hatch, (4) offspring sex, (5) maternal female size and body condition at hatch, and (6) weather. We estimated survival with Cormack-Jolly-Seber models, in program MARK, from observations of individually marked adult females (n = 94) and ducklings (n = 664). Most mortality (i.e. 0.80 and 0.95 for each year, respectively) occurred within six days of hatch in both years. Duckling survival probability decreased with advancing hatch date; increased with larger initial brood sizes; was higher for larger, better-conditioned ducklings; and increased with favorable weather. Brood survival decreased with advancing hatch date, increased with larger initial brood sizes, and increased with favorable weather. For 2000 and 2001, our models predict survival probabilities of ducklings (0.0061 and 0.0027, respectively) and broods (0.015 and 0.00048, respectively) that are lower than any previously reported. We suspect that intense gull (Larus spp.) predation shortly after hatch had the largest influence on duckling survival, though results also underscore the significance of intrinsic factors.Effets des Facteurs Intrinsèques et Extrinsèques sur la Survie les Jeunes de Melanitta fusca deglandi

EFFECTS OF INTRINSIC AND EXTRINSIC FACTORS ON SURVIVAL OF WHITE-WINGED SCOTER (MELANITTA FUSCA DEGLANDI) DUCKLINGS

Abstract In waterfowl, offspring survival and the effects of extrinsic (i.e. weather, hatching date) and intrinsic (i.e. physical and nutritional traits of individual females and ducklings, brood sizes) factors on it are poorly understood. In 2000 and 2001, we estimated duckling and brood survival of White-winged Scoters (Melanitta fusca deglandi) at Redberry Lake, Saskatchewan, Canada, to 30 days of age to examine relationships between duckling survival and (1) hatch date, (2) initial brood size at hatch, (3) duckling size and body condition at hatch, (4) offspring sex, (5) maternal female size and body condition at hatch, and (6) weather. We estimated survival with Cormack-Jolly-Seber models, in program MARK, from observations of individually marked adult females (n = 94) and ducklings (n = 664). Most mortality (i.e. 0.80 and 0.95 for each year, respectively) occurred within six days of hatch in both years. Duckling survival probability decreased with advancing hatch date; increased with larger initial ...

Competitive mechanisms in a food-limited species: relative importance of interference and exploitative interactions among labyrinth spiders (araneae: Araneidae).

Field experiments were conducted to clarify the relationship between the extent of food limitation and the amount and nature of intraspecific competition in an orb weaver, the labyrinth spider Metepeira labyrinthea. In one experiment agonistic encounters between marked adult females were induced at natural web sites. In other experiments populations were established by adding spiders to standardized, open experimental units in the spider's natural habitat. Replicate low and high density populations of marked adult females were established in one study. The other density manipulation was with immature spiders and incorporated a third treatment in which prey availability was increased over ambient levels.The larger female gained control of the web in 76% of the induced encounters. Resident status of the spider did not significantly influence the outcome of a contest. Apparently labyrinth spiders will spontaneously invade webs, since some females in the density-manipulation experiment appeared in recently occupied webs of other spiders. Despite this evidence of interference competition and indirect evidence that prey scarcity limited fecundity, neither survival nor egg production was lower at higher spider densities. The experiment with juvenile spiders provided direct experimental evidence that prey were scarce for M. labyrinthea. Spiders that received supplemental food were significantly larger at the end of the experiment than those that fed at natural prey levels only (24±3 mg versus 15±2 mg, respectively). However, density of immature spiders did not affect their growth or survival.The labyrinth spider appears to be a food-limited species in which exploitative competition for food is weak or absent. Most spiders never build webs close enough together to interfere indirectly with each other's prey capture. Occurrence of aggressive interactions between some females suggests that territorial behavior may lead to spacing patterns that eliminate exploitative competition. This hypothesis is evaluated and it is concluded that other factors better explain the absence of exploitative competition among most M. labyrinthea. Aggressive encounters occur between some labyrinth spiders and clearly constitute interference competition, but such interactions do not contribute significantly to density-dependent regulation of this population.

Overharvest of Fox Squirrels from Two Woodlots in Western Ohio

Harvests of fox squirrels (Sciurus niger) from 54 acres (21.8 hectares) of oak-hickory woodlots located on a public shooting area in western Ohio were analyzed to determine the effects of hunting on the squirrel population over a 7-year period, 1965-71. Yields averaged 1.00 squirrel per acre (2.5 squirrels per hectare) the first 4 years, 1965-68, but declined significantly to an average of 0.60 squirrel per acre (1.5 squirrels per hectare) the last 3 years, 1969-71. Squirrel harvests were significantly correlated with the preseason squirrel density but were not significantly correlated with hunting pressure each year. High sustained hunting pressure and the ease of hunter access to all portions of two woodlots combined to allow hunters to shoot a high proportion of the resident squirrel population. Hunters recovered an average of 47.1 percent of the marked adult females, 59.1 percent of the adult males, 33.3 percent of the subadult females, and 58.1 percent of the subadult males in the first hunting season after tagging. The average annual mortality for marked adults and subadults combined was 91.8 percent; 75.2 percent of this mortality was a result of hunting. Preseason squirrel densities in the total harvest were significantly correlated with the kill of subadults, the recovery rate of adults, and the total kill of adults for the previous year. During the last 3 years, 1969-71, the adult squirrel population was reduced by hunting to a level that could not produce enough young to bring preseason densities up to 1965-68 levels. There was a substantial immigration of subadults into the study area during the hunting season in the last 4 years. Small wood lots on public hunting areas may be difficult to manage for fox squirrels without some restraint on hunting opportunity. Management of these woodlots should be based on a concept of sustained yield rather than on hunter success, because hunter demand far exceeds the supply of squirrels. J. WILDL. MANAGE. 38(1):67-80 Fox squirrels inhabiting public hunting areas are frequently subject to annual hunting pressures several times higher than squirrels on privately owned forests (Peterle and Fouch 1959). Each year as hunting opportunities decline on private lands, more squirrel hunters seek their recreation on public hunting areas. Game managers should be concerned with the effects of this continuing heavy hunting pressure, particularly as the resulting squirrel harvests affect population densities and the maintenance of population equilibrium from year to year. The present paper reports on 7 years of harvest data (1965-71) for 54 acres (21.8 hectares) of woodlots located on a public hunting area in western Ohio. Our aim was to study the effects of hunting on a fox squirrel population exposed to relatively long (88-98 days) hunting seasons that began in early September before many litters born in midto late summer were weaned. In extensive forests there seems little doubt that both gray (S. carolinensis) and fox squirrels are usually underharvested (Allen 1952, Uhlig 1955). However, Allen (1943:335), Allen (1952:28), and Baumgartner (1943:193) reported overshooting of fox squirrels inhabiting small woodlots in Michigan, Indiana, and Ohio, respectively. These authors believed that squirrel populations in woodlots were sustained by an immigration of squirrels from adjacent, more lightly hunted, populations. Where woodlots were small and widely separated, population recovery was slow after years of high kill (Baumgartner 1943:193). 1A contribution of Federal Aid in Wildlife Restoration Projects, Ohio W-105-R and Illinois W66-R. J. Wildl. Manage. 38(1):1974 67 This content downloaded from 207.46.13.126 on Sat, 24 Sep 2016 04:49:41 UTC All use subject to http://about.jstor.org/terms 68 OVERHARVEST OF OHIO SQUIRRELS * Nixon et al. Peterle and Fouch (1959) published the only long-term study of the effects of hunting on fox squirrels in woodlots. They found that short (22 days) October hunting seasons did not materially change the fox squirrel population. We acknowledge personnel of the Ohio Division of Wildlife who assisted with livetrapping and operation of the checking station. H. C. Schultz and W. R. Edwards, Illinois Natural History Survey, reviewed the manuscript.