conservation.arizona.edu - Arizona

Munroe, K.E., and J.L. Koprowski. 2011. Sociality, Bateman’s gradients and the polygynandrous genetic mating system of round-tailed ground squirrels (Xerospermophilus tereticaudus). Behavioral Ecology and Sociobiology. 65: 1811-1824.

thackerk1 — Tue, 23 Jul 2019 23:45:01 +0000

Authors

Karen E. Munroe

John L. Koprowski

Historically, most mammals have been classified as polygynous; although recent molecular evidence suggests that many mammals may be polygynandrous, particularly the ground-dwelling sciurids. We genotyped 351 round-tailed ground squirrels (Xerospermophilus tereticaudus) using seven microsatellite loci to determine paternity in 31 litters from 2004 to 2007. Polygyny was evident in all years except in 2007, when the population size was reduced. Multiple paternity occurred in the majority of litters (55%) with 2.5±0.26 sires/litter (n=31). Forty-nine percent of resident males (n = 114) sired offspring, and of males that sired offspring (n=56) 27% sired young in multiple litters in a single breeding season. Litter size was positively correlated with the number of sires. Through an indirect analysis of paternity, we found 21 litters (68%) with an average relatedness of 0.5 or less. Males had a greater opportunity for sexual selection (Is = 1.60) than females (Is = 0.40); Bateman’s gradient was also greater in males (1.07 ± 0.04, n = 56) than females (0.82 ± 0.08, n = 31). The mating system in round-tailed ground squirrels defined through genetic analyses and Bateman’s gradients is polygynandrous compared to the previously suggested polygynous mating system as established by behavioral observations and fits within the predictions of the ground squirrel sociality models. Upon evaluating the predictions of the sociality models among sciurid species, we found a negative relationship between the level of sociality with litter size and the average percentage of multiple paternity within a litter. Thus, recent genetic information and reclassification of mating systems support the predictions of the ground-dwelling squirrel sociality models.

Additional Information

Sociality, Bateman’s gradients, and the polygynandrous genetic mating system of round-tailed ground squirrels (Xerospermophilus

Date of publication:

2011

Topics

round-tailed ground squirrels

sociality

Arizona

polygynandry

multiple paternity

microsatellites

parentage analysis

Munroe, K. E., and J. L. Koprowski. 2014. Levels of social behaviors and genetic structure in a population of round-tailed ground squirrels (Xerospermophilus tereticaudus). Behavioral Ecology and Sociobiology 68:629-638.

thackerk1 — Tue, 23 Jul 2019 23:41:49 +0000

Authors

Karen E. Munroe

John L. Koprowski

Ground-dwelling sciurids exhibit a continuum of sociality and several models predict levels of sociality within this taxon. Models of ground squirrel sociality predict round- tailed ground squirrels (Xerospermophilus tereticaudus) to be solitary; however, previous behavioral studies suggest round-tailed ground squirrels have a matrilineal social structure. To resolve this discrepancy, we combined behavioral observations with genetic analyses of population structure. We assessed levels of agonistic and amicable behaviors combined with fine-scale population genetic structure of round-tailed ground squirrels in a multi-year study in AZ. Only 45 agonistic and 40 amicable interactions were observed between adults in over 137 h of observations. Overall rates of agonistic or amicable interactions between adults were low (≤0.69/h), with no relationship between relatedness of individuals and rates of either amicable or agonistic interactions. Interactions between juvenile littermates were predominantly amicable. Population substructure was not evident with Bayesian analyses, global or pairwise FST values; average relatedness among females was not different from males. However, in 2006, the year after a population reduction through targeted animal elimination, a population bottleneck was detected within at least five of seven loci. Contrary to previous behavioral studies, this population of round-tailed ground squirrels, although aggregated spatially, did not exhibit high levels of social behavior nor subpopulation genetic structure. Analyses of the genetic relationships and sociality along a continuum, particularly within aggregates of individuals, may lead to insights into the origin and maintenance of social behaviors by elucidating the mechanisms by which aggregates with intermediate social levels are formed and maintained.

Additional Information

Levels of social behaviors and genetic structure in a population of round-tailed ground squirrels (Xerospermophilus tereticaudus

Date of publication:

2014

Topics

round-tailed ground squirrels

Arizona

bottleneck

sociality

microsatellites

sciuridae

Merrick, M. J., S. R. Bertelsen, and J. L. Koprowski. 2007. Characteristics of Mount Graham red squirrel nest sites in a mixed conifer forest. The Journal of Wildlife Management 71: 1958-1963.

thackerk1 — Tue, 23 Jul 2019 23:39:01 +0000

Authors

Melissa J. Merrick

Sadie R. Bertelsen

John L. Koprowski

The Mount Graham red squirrel (Tamiasciurus hudsonicus grahamensis) is constrained to the Pinaleńo Mountains in southeastern Arizona, USA. The population’s endangered status and extensive forest damage from insects and fire warrants a better understanding of habitat variables important for nest site selection. We examined characteristics of cavity (n 1⁄4 91) and drey (n 1⁄4 38) nests and compared these to random sites (n 1⁄4 113). Dreys were found primarily in Engelmann spruce (Picea engelmannii) and corkbark fir (Abies lasiocarpa var. arizonica). Cavity nests occurred primarily in aspen (Populus tremuloides) and corkbark fir. Squirrels selected nest sites with higher canopy cover and more corkbark fir, decayed logs, and living trees. Forest management plans emphasizing thinning must consider how altering these habitat characteristics could affect availability and suitability of tree stands for nesting squirrels. (JOURNAL OF WILDLIFE MANAGEMENT 71(6):1958–1963; 2007)

Additional Information

Characteristics of Mount Graham Red Squirrel Nest Sites in a Mixed Conifer Forest

Date of publication:

2007

Topics

Arizona

habitat selection

Mount Graham Red Squirrel

nest-site selection

Evidence of natal habitat preference induction within one habitat type

thackerk1 — Tue, 23 Jul 2019 23:24:14 +0000

Authors

Melissa J. Merrick

John L. Koprowski

Natal habitat preference induction (NHPI) is a mechanism for habitat selection by individuals during natal dispersal. NHPI occurs in wild animal populations, and evidence suggests it may be a common, although little studied, mechanism for post-dispersal habitat selection. Most tests of NHPI examine the influence of distinct, contrasting natal habitat types on post-dispersal habitat selection. We test the hypothesis that NHPI can occur within a single habitat type, an important consideration for habitat specialists. The Mount Graham red squirrel (Tamiasciurus hudsonicus grahamensis) is an endangered forest obligate restricted to a single mountain primarily within mixed-conifer forest. We test for NHPI by comparing intra-individual differences in natal and settlement habitat structure and composition to expected random pairwise differences. Dispersing juveniles appear to select settlement locations that are more similar to natal areas than expected in several forest structure and composition variables that include canopy cover and live basal area. Our results provide support for NHPI as a mechanism for post-dispersal habitat selection in habitat specialists that occupy a single vegetation community type.

Additional Information

Proceedings of the Royal Society B

Date of publication:

2016

Topics

natal dispersal

natal habitat

habitat selection

Arizona

Mount Graham Red Squirrel

behavior

Research Categories

Behavioral Ecology Sky Islands Spatial Ecology Threatened and Endangered Species

Circuit theory to estimate natal dispersal routes and functional landscape connectivity for an endangered small mammal.

thackerk1 — Tue, 23 Jul 2019 23:06:39 +0000

Authors

Melissa J. Merrick

John L. Koprowski

Context Natal dispersal links population dynamics to landscape connectivity. Understanding how organisms perceive barriers to movement, or landscape resistance, during natal dispersal is important to conserve and manage populations threatened by fragmentation and habitat loss.

Objectives We aimed to (1) model probability of landscape use by an endangered small mammal (Tamiasciurus hudsonicus grahamensis) in the Pinaleño Mountains, Arizona, USA as a function of forest structure at the population and intra-population level, (2) identify potential natal dispersal pathways between natal and settlement locations based on landscape resistance scenarios, and (3) assess which resistance surface best represented observed exploration, disper- sal, and settlement.

Methods We modeled probability of habitat use via used and available animal locations. We developed three landscape resistance scenarios to represent individual differences in perceived resistance. We used circuit theory to identify potential long-distance dispersal pathways and to assess which resistance scenario best represented observed forest use and settlement.

Results Top probability of forest use models included physical landscape features, forest structure, and burn severity. Composite connectivity models, created from multiple resistance scenarios, identified areas that may promote long distance dispersal move- ments. Connectivity models developed from only natal focal nodes allowed for assessment of resistance scenarios; a non-linear, negative-exponential relationship between probability of use and resistance best represented observed exploration and settlement. Conclusions Circuit theory is a useful tool to identify potential small mammal movement pathways when high temporal resolution movement data are limited, and for assessing how well resistance scenarios represent observed settlement patterns.

Additional Information

Landscape Ecology

Date of publication:

2017

Topics

Arizona

Pinaleño Mountains

point selection function

small mammal

resistance surface

circuitscape

Research Categories

Disturbance Ecology Sky Islands Spatial Ecology Threatened and Endangered Species

White-nosed coatis in Arizona: tropical carnivores in a temperate environment

thackerk1 — Tue, 23 Jul 2019 22:39:56 +0000

Authors

Maureen E. McColgin

John L. Koprowski

Peter M. Waser

Intraspecific variation in ranging and social behavior can be perplexing, but also provides an opportunity to assess which behavioral attributes are labile in the face of geographic variation in resources. White-nosed coatis (Nasua narica) are group-living carnivores of tropical origin that possess an unusual social system. In the resource- rich tropics, larger-bodied males are solitary, whereas females live in groups (“bands”) along with young of both sexes, but leave them to give birth and wean their young. Males often disperse socially, but not spatially. We studied coatis in the Chiricahua National Monument, Arizona, a resource-poor, arid, and highly seasonal landscape. Using live capture and radiotelemetry in conjunction with microsatellite DNA analyses, we found that Chiricahua coatis exhibited the species-typical pattern of solitary males and gregarious females. Young males left their natal bands as yearlings, and some were found as adults within their natal home range. On the other hand, home ranges were expanded greatly. Bands, and some males, focused their movements in areas several km2 in extent over periods of weeks or months but shifted those areas markedly among seasons. Some males followed the typical mammalian pattern of natal dispersal beyond their natal area. Rates of movement were higher and female associations appeared to be more flexible than in the tropics. Adult females sometimes ranged singly, not only around the time of parturition, but also when population density was low and occasionally otherwise. In addition, home range overlap was high among both sexes during some seasons, and female bands sometimes fused for prolonged periods. Core patterns of sociality are constant in both resource-rich tropical and resource- poor temperate populations, but coatis appear to make major adjustments in scale of movement and frequency of association in response to resource variation.

Additional Information

Journal of Mammalogy

Date of publication:

2017

Topics

Arizona

white-nosed coatis

dispersal

home range

social organization

group structure

Research Categories

Behavioral Ecology Natural History Sky Islands Spatial Ecology

Koprowski, J. L. and M. C. Corse. 2005. Time budgets, activity periods, and behavior of mexican fox squirrels. Journal of Mammalogy 86(5): 947-952.

thackerk1 — Mon, 22 Jul 2019 23:31:09 +0000

Authors

John L. Koprowski

Michelle C. Corse

Resources that limit reproductive success differ between the sexes in many vertebrates. We used focal animal observations to determine sex-specific activity periods, time budgets, and movements of endemic Mexican fox squirrels (Sciurus nayaritensis chiricahuae) in montane forests of southeastern Arizona during June, August, and December 1994 and January 1995. Activity periods during summer were bimodal with peaks in morning and afternoon separated by a midday lull in activity; winter activity was unimodal. No sex differences were detected in activity periods, although males retired later than females in winter. Resting, feeding, and locomotion were the most common behaviors and accounted for .75% of activities of each sex. Activity by females did not differ between seasons. Males spent more time in locomotion in summer and more time feeding in winter than in other seasons. Differences in time budgets of the sexes suggest that males and females apportion daily activity to maximize access to resources that limit fitness of each sex.

Additional Information

TIME BUDGETS, ACTIVITY PERIODS, AND BEHAVIOR OF MEXICAN FOX SQUIRRELS

Date of publication:

2005

Topics

Arizona

sex differences

sexual dimorphism

Mexican fox squirrels

Koprowski, J. L. 2005. Annual cycles in body mass and reproduction of endangered Mt. Graham red squirrels. Journal of Mammalogy 86(2): 309-313

thackerk1 — Mon, 22 Jul 2019 23:18:39 +0000

Authors

John L. Koprowski

Annual cycles in life-history traits often are interpreted as adaptations. The Mt. Graham red squirrel (Tamiasciurus hudsonicus grahamensis) is an endangered species isolated in the Pinaleno Mountains of Arizona (United States) at the southernmost range terminus where the ecology is poorly known. I monitored annual cycles of reproduction and body mass in male and female Mt. Graham red squirrels. Males with scrotal testes were present during all months except October, with a peak in testis size in April. Lactating females were found from April to September. Male body mass was highest in winter and lowest in summer; females did not fluctuate seasonally in mass. Male body mass exceeded that of females during winter and was positively related to size of testes late in the breeding season. Annual cycles in reproduction and body mass of Mt. Graham red squirrels are similar to those of other red squirrels in similar life zones.

Additional Information

ANNUAL CYCLES IN BODY MASS AND REPRODUCTION OF ENDANGERED MT. GRAHAM RED SQUIRRELS

Date of publication:

2005

Topics

Arizona

body mass

mating systems

Mount Graham Red Squirrel

sex differences

energetics

Koprowski, J. L., M. I. Alanen, and A. M. Lynch. 2005. Nowhere to run and nowhere to hide: Response of endemic Mt. Graham red squirels to catastrophic forest damage. Biological Conservation 126: 491-498.

thackerk1 — Mon, 22 Jul 2019 23:16:00 +0000

Authors

John L. Koprowski

Marit I. Alanen

Ann M. Lynch

A consequence of isolation is increased susceptibility to catastrophe. Insect damage to fragmented and isolated forests has the potential to serve as a catastrophic force; such damage has increased worldwide due to climate change and fire suppression policies. We examined the response of endangered endemic Mt. Graham red squirrels to catastrophic insect damage due to moths, beetles, and introduced aphids. Insects changed the forest environment significantly for the endemic squirrel by reducing basal area and stem densities of live stems, while increasing number and basal area of standing dead stems. Availability of two major foods, fungi and tree seeds, declined in insect-damaged forests relative to trends in undamaged forests. Numbers of Mt. Graham red squirrels declined precipitously in insect-damaged forests suggesting a catastrophe. Conservation options are limited in such situations. Forest-insect induced catastrophes are likely to become more common in the near future as forest health declines due to past management tactics and climate change. Prudent conservation measures include the anticipation of insect outbreaks and effective forest treatments to decrease likelihood of such catastrophes to species of precarious conservation status, while avoiding abrupt changes to critical habitat.

Additional Information

Nowhere to run and nowhere to hide: Response of endemic Mt. Graham red squirrels to catastrophic forest damage

Date of publication:

2005

Topics

bark beetle

aphid

forest health

climate change

Arizona

Mount Graham Red Squirrel

insect-damage

Koprowski, J. L., S. R. B. King, and M. J. Merrick. 2008. Expanded home ranges in a peripheral population: space use by endangered Mt. Graham red squirrels. Endangered Species Research, 4:227-232.

thackerk1 — Mon, 22 Jul 2019 23:04:35 +0000

Authors

John L. Koprowski

Sarah R. B. King

Melissa J. Merrick

Peripheral populations are often of increased conservation value; however, knowledge of the ecological and evolutionary consequences of a peripheral location is poor. Spatial dynamics are often interpreted as strategies to maximize access to fitness-limiting resources. Red squirrels Tamiasciurus hudsonicus are territorial in western portions of their range and exhibit overlapping home ranges in eastern forests. Endangered Mt. Graham red squirrels T. hudsonicus grahamensis represent the southernmost extension of the species. We used radiotelemetry to assess space use and interindividual overlap of endangered Mt. Graham red squirrels. Squirrels maintained nearly exclusive 50% core areas; however, 95% ranges overlapped considerably, especially between males and females. Home ranges increased in summer for both males and females and may be related to sex-specific reproductive strategies. Ranges of Mt. Graham red squirrels in this peripheral population were nearly 10 times the size of red squirrels from other locations. The space use of this limital population suggests that resource availability may be substantially different than in other portions of the range.

Additional Information

Expanded home ranges in a peripheral population: space use by endangered Mt. Graham red squirrels

Date of publication:

2008

Topics

limital population

geographic range

Arizona

conservation

Mount Graham Red Squirrel

red squirrel