Progress 04/01/11 to 09/30/15
Outputs
Target Audience:The target audience consists of those who suffer from damage from squirrels and their activities and who desire effective solutions. During the reporting period I worked with numerous agencies (e.g., City of Berkeley, City of Ventura, Sacramento Area Flood Control Agency, California Department of Water Resources) to develop solutions to squirrel problems. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Training and professional development were provided for five graduate students, two professional students, and two undergraduate students. How have the results been disseminated to communities of interest?Participated in a UC Cooperative Extension workshop on montane mammals; presented about burrowing mammals in a workshop on levee vegetation and safety; advised the California Department of Water resources on burrowing ground squirrels; advised the Ventura County Watershed Protection District about burrowing ground squirrels; advised the City of Berkeley about burrowing ground squirrels and water quality; extended knowledge to the Denver Post about damage caused by ground squirrels, and the Sonora Union-Democrat about effects of climate change on hibernating squirrels; was interviewed for National Public Radio about effects of climate change on hibernating ground squirrels. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Squirrels were trapped, ear-tagged, and dye-marked for individual recognition, then tracked via intensive behavioral observations to determine spatial and temporal dynamics. Time of snow melt was revealed as an important determinant of onset of the active season and time of mating for squirrels, but it is not the sole factor; determinants of squirrel phenology appear to be complex. Summer rainfall also appears to influence reproduction because squirrels remain belowground during wet weather, reducing their forage intake and consequently their growth rate and ability to store fat to support hibernation and reproduction the following spring. Both time of snow melt and summer precipitation are expected to altered by climate change.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2014
Citation:
Van Vuren, D. H., M. A. Orde�ana, M. C. McGrann, and A. R. Berentsen. 2014.
Managing California ground squirrels on levees using habitat modification.
Proceedings of the Vertebrate Pest Conference 26:180-183.
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Kelt, D. A., and D. H. Van Vuren. 2015. Home ranges of Recent mammals.
Ecology 96:1733.
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Krause, S. K., D. H. Van Vuren, C. Laursen, and D. A. Kelt. 2015. Behavior effects of an immunocontraceptive vaccine on eastern fox squirrels. Journal of Wildlife Management 79:1255-1263.
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Progress 10/01/13 to 09/30/14
Outputs
Target Audience: The target audience consists of those who suffer from damage from squirrels and their activities and who desire effective solutions. During the reporting period I worked with numerous agencies (e.g., City of Berkeley, City of Ventura, Sacramento Area Flood Control Agency, California Department of Water Resources) to develop solutions to squirrel problems. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? One graduate students and one post-graduate student received extensive training in field biology How have the results been disseminated to communities of interest? I was interviewed and recorded for a series of National Public Radio shows on the effects of climate change. What do you plan to do during the next reporting period to accomplish the goals? Continue studying the impacts of climate change on the temporal and spatial dynamics of squirrel populations.
Impacts
What was accomplished under these goals?
During the 2013 review period squirrels were trapped, ear-tagged, and dye-marked for individual recognition, then tracked via intensive behavioral observations to determine spatial and temporal dynamics. Unlike previous years, females mated at about the time predicted by time of snow melt in May, and litter emergence was closely coincidence it time, indicating that this year females responded to the same environmental cue. This result has important implications for climate change, which is predicted to result in a mismatch between the cues animals use to initiate reproduction and the actual timing of resource availability.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Krause, S. K., D. A. Kelt, J. P. Gionfriddo, and D. H. Van Vuren. 2014. Efficacy and
health effects of a wildlife immunocontraceptive vaccine on fox squirrels. Journal of Wildlife Management 78:12-23.
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
McGrann, M. C., D. H. Van Vuren, and M. A. Orde�ana. 2014. Influence of adjacent
crop type on occurrence of California ground squirrels on levees in the Sacramento Valley, California. Wildlife Society Bulletin 38:111-115.
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Krause, S. K., D. A. Kelt, D. H. Van Vuren, and J. P. Gionfriddo. 2014. Regulation of
tree squirrel populations with immunocontraception: a fox squirrel example.
Human-Wildlife Interactions 8:168-178.
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Progress 01/01/13 to 09/30/13
Outputs
Target Audience: The target audience consists of those who suffer from damage from squirrels and their activities and who desire effect solutions. During the reporting period I attended numerous meetings with affected clientele in the Sacramento region. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Two graduate students and one high school biology teacher received extensive training in field biology. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals? Continue studying the impacts of climate change on the temporal and spatial dynamics of squirrel populations.
Impacts
What was accomplished under these goals?
During the 2013 review period 121 golden-mantled ground squirrels were trapped, ear-tagged, and dye-marked for individual recognition, then tracked via intensive behavioral observations to determine spatial and temporal dynamics. Snow began melting early this year, but late-spring storms lengthed the time at which soil was exposed and vegetation growth began. The result was the some females bred later than expected based on snow depth in May, and that other females mated but lost their litters (presumably the fetuses were resorbed). This result has important implications for climate change, which is predicted to result in a mismatch between the cues animals use to initiate reproduction and the actual timing of resource availability.
Publications
|
Progress 01/01/12 to 12/31/12
Outputs
OUTPUTS: During 2012, 71 golden-mantled ground squirrels were trapped, ear-tagged, and dye-marked for individual recognition, then tracked via intensive behavioral observations to determine spatial and temporal dynamics. Time of snow melt was very early this year, and litters were all born early as well. However, unlike prior years with early snow melt, timing of reproduction was clumped - all litters emerged within 11 days. Losses due to predation (red foxes, weasels) were modest. PARTICIPANTS: Dirk Van Vuren was the project PI, and Caitlin Wells, Hae Yeong Ryu, and Kat Tomalty participated in the project as research assistants. The experience was important training and professional development for Wells and Ryu (PhD dissertation), and Tomalty (internship for DVM degree). TARGET AUDIENCES: The target audience consists of those who suffer from damage from squirrels and their activities and who desire effect solutions. During the year attended numerous meetings with affected clientele in the Sacramento region. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
An important question about response to climate change is the consistency with which individuals of a species respond. Past work in this study suggest that some female responded to early snow melt by breeding early, but some did not. This year, all females bred early, suggesting that in some years, some females exhibit lag effects.
Publications
- Armitage, K. B., D. H. Van Vuren, A. Ozgul, and M. K. Oli. 2011. Proximate causes of natal dispersal in female yellow-bellied marmots Marmota flaviventris. Ecology 92:218-227.
- Jesmer, B. R., D. H. Van Vuren, J. A. Wilson, D. A. Kelt, and M. L. Johnson. 2011. Spatial organization in female golden-mantled ground squirrels. American Midland Naturalist 165:162-168.
- McEachern, M. B., D. H. Van Vuren, C. H. Floyd, B. May, and J. M. Eadie. 2011. Bottlenecks and rescue effects in a fluctuating population of golden-mantled ground squirrels (Spermophilus lateralis). Conservation Genetics 12:285-296.
- Hostetler, J. A., E. Kneip, D. H. Van Vuren, and M. K. Oli. 2012. Stochastic population dynamics of a montane ground-dwelling squirrel. PLoS ONE 7(3):1-10; e34379.
- Van Vuren, D. H., and M. A. Ordenana. 2012. Factors influencing burrow length and depth of ground-dwelling squirrels. Journal of Mammalogy 93:1240-1246. Ordenana, M. A., D. H. Van Vuren, and J. P. Draper. 2012. Habitat associations of California ground squirrels and Botta's pocket gophers on levees in California. Journal of Wildlife Management 76:1712-1717.
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Progress 01/01/11 to 12/31/11
Outputs
OUTPUTS: During 2011, 59 golden-mantled ground squirrels were trapped, ear-tagged, and dye-marked for individual recognition, then tracked via intensive behavioral observations to determine spatial and temporal dynamics. Time of snow melt was average this year, so reproduction was fairly high. Losses due to predation (red foxes, weasels) were very low this year. PARTICIPANTS: Dirk Van Vuren was the project PI, and Caitlin Wells, Jessica Huang, and Michelle Morelos participated in the project as paid research assistants. The experience was important training and professional development for, Wells (PhD dissertation), Huang (undergraduate research experience), and Morelos (internship for DVM degree). TARGET AUDIENCES: The target audience consists of those who suffer from damage from squirrels and their activities and who desire effect solutions. During the year attended numerous meetings with affected clientele in the Sacramento region. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Predation rate in recent years has varied greatly, with major impacts on population size; if this predation rate can be managed and promoted, predation may be an important factor for managing squirrel populations. Predicting the effects of climatic factors on squirrel populations is important as well. Years with delayed snow melt likely will result in low reproduction, leading to depressed population size the following year.
Publications
- Kneip, E., D. H. Van Vuren, J. A. Hostetler, and M. K. Oli. 2011. Relative influence of population density and climate on the demography of a subalpine population of golden-mantled ground squirrels. Journal of Mammalogy 92:367-377.
- Smith, J. R., D. H. Van Vuren, D. A. Kelt, and M. L. Johnson. 2011. Spatial organization of northern flying squirrels, Glaucomys sabrinus: territoriality in females Western North American Naturalist 71:44-48.
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: During 2010, 61 golden-mantled ground squirrels were trapped, ear-tagged, and dye-marked for individual recognition, then tracked via intensive behavioral observations to determine spatial and temporal dynamics. Numbers of adults remained low this year, probably due to fox predation, suggesting that predation is sufficient to keep numbers low. During 2010, results about temporal and spatial dynamics of squirrel populations were disseminated at a major workshop in Sacramento and another at Quincy. PARTICIPANTS: Dirk Van Vuren was the project PI, and Eva Kneip, Caitlin Wells, and Katie Sahyouni participated in the project as paid research assistants. The experience was important training and professional development for Kneip (master's thesis), Wells (PhD dissertation), and Sahyouni (internship for DVM degree). TARGET AUDIENCES: The target audience consists of those who suffer from damage from squirrels and their activities and who desire effect solutions. During the year I gave presentations at workshops in Sacramento and Quincy that effectively reached the target audience. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The finding that predation may keep squirrel populations low is significant because predation is often proposed as a means of controlling squirrel pests, but data on efficacy are scarce. Results from 2010 suggest that predation may have a role in managing squirrel pests.
Publications
- McEachern, M. B., D. H. Van Vuren, C. H. Floyd, B. May, and J. M. Eadie. 2011. Bottlenecks and rescue effects in a fluctuating population of golden-mantled ground squirrels (Spermophilus lateralis). Conservation Genetics 12:285-296.
- Jesmer, B. R., J. A. Wilson, D. A. Kelt, and M. L. Johnson. 2011. Spatial organization in female golden-mantled ground squirrels. American Midland Naturalist 165:162-168.
- Armitage, K. B., D. H. Van Vuren, A. Ozgul, and M. K. Oli. 2011. Proximate causes of natal dispersal in female yellow-bellied marmots Marmota flaviventris. Ecology, in press.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: During 2009, 53 golden-mantled ground squirrels were trapped, ear-tagged, and dye-marked for individual recognition, then tracked via intensive behavioral observations to determine spatial and temporal dynamics. This year was notable because of an important change population dynamics -squirrel numbers are starting to increase, after a drastic decline two years ago caused almost entirely be predation by a red fox. A fox is still present, but the one that caused the decline died overwinter 2008-2009, and the resident fox is likely an offspring. This new fox is a less efficient hunter, as most predation attempts that we witness were failures, in contrast to the prior resident fox. Further, numbers of squirrels observed killed is greatly reduced from 2007 and 2008. This pattern suggests that although predators can have a major influence on prey population dynamics, the experience and ability of the predator has an important role. PARTICIPANTS: George Aldridge, Caitlin Wells, and Eva Kniep participate in the project as research assistants, trapping and observing squirrels. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Many species of ground squirrels are considered pests and are threats to agriculture and public health. Designing effective control programs requires information on basic ecology and behavior of the pest species. My results on temporal and spatial dynamics of ground squirrels enhance our knowledge of how pest species respond to environmental factors, allowing managers to design control programs that are more effective at reducing damage by squirrels.
Publications
- No publications reported this period
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: During 2007, 38 golden-mantled ground squirrels were trapped, ear-tagged, and dye-marked for individual recognition, then tracked through intensive behavioral observations to determine spatial and temporal dynamics. Squirrel numbers remained relatively low, primarily because of continued predation on adult females by a red fox. This dynamic is a departure from a previous population low, when an increase was prevented by low rates of reproduction and recruitment. During 2008, rates of reproduction were high, but several pregnant adult females were killed before producing their litters. These results illustrate how timing of predation can influence biological control through predation. Additionally, timing of reproduction was very late this year, corresponding to late snowmelt, suggesting that females can adjust reproduction in response to forage phenology. PARTICIPANTS: George Aldridge participated in the project as a research assistant, trapping and observing squirrels. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Many species of ground squirrels are considered pests and are threats to agriculture and public health. Designing effective control programs requires information on basic ecology and behavior of the pest species. My results on temporal and spatial dynamics of ground squirrels enhance our knowledge of how pest species respond to environmental factors, allowing managers to design control programs that are more effective at reducing damage by squirrels.
Publications
- Ozgul, A. M. K. Oli, K. B. Armitage, D. T. Blumstein, and D. H. Van Vuren. 2009. Influence of local demography on asymptotic and transient dynamics of a yellow-bellied marmot population. American Naturalist (in press).
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Progress 01/01/07 to 12/31/07
Outputs
During 2007, 28 golden-mantled ground squirrels were trapped, ear-tagged, and dye-marked for individual recognition, then tracked through intensive behavioral observations to determine spatial and temporal dynamics. The three-year peak in population density (2004-2006) ended last summer, and numbers during 2007 were down by at least 75%. There is strong evidence that the cause of this precipitous decline is one female red fox who focused her hunting efforts on grounds squirrels. Surprisingly, this fox has lived on the study area for several years, but until summer 2006 seldom hunted squirrels. Two important conclusions emerge about population dynamics of squirrels. First, a single predator can cause the decline of a population. Second, this high predation rate was caused not by a numerical increase in the predator, but by a functional response, a behavioral shift, that occurred on one predator, for uncertain reasons. Hence, this finding sheds light on the potential for
predators to function as a "biological control" of pest species.
Impacts
Many species of ground squirrels are considered pests and are threats to agriculture and public health. Designing effective control programs requires information on basic ecology and behavior of the pest species. My results on temporal and spatial dynamics of ground squirrels enhance our knowledge of how pest species respond to environmental factors, allowing managers to design control programs that are more effective at reducing damage by squirrels.
Publications
- No publications reported this period
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Progress 01/01/06 to 12/31/06
Outputs
During 2006, 83 golden-mantled ground squirrels were trapped, ear-tagged, and dye-marked for individual recognition, then tracked through intensive behavioral observations to determine spatial and temporal dynamics. The peak in population density, which has continued for an unprecedented three years, showed evidence of a decline when fewer adults emerged from hibernation in late spring. However, the population declined sharply during the summer, largely because of one adult female red fox that focused on ground squirrels as prey. Red foxes have been present at the study site for many years and annually kill some ground squirrels, but this summer predation was exceptionally intense, perhaps because of scarcity of alternate prey such as gophers and voles. These results suggest that two factors, reduced overwinter survival and intense active-season predation, acted in concert to cause the decline in population size.
Impacts
Many species of ground squirrels are considered pests and are threats to agriculture and public health. Designing effective control programs requires information on basic ecology and behavior of the pest species. My results on temporal and spatial dynamics of ground squirrels enhance our knowledge of how pest species respond to environmental factors, allowing managers to design control programs that are more effective at reducing damage by squirrels.
Publications
- Blumstein, D. T., A. Ozgul, Y. Yovovich, D. H. Van Vuren, and K. B. Armitage. 2006. Effect of predation risk on the presence and persistence of yellow-bellied marmot (Marmota flaviventris) colonies. Journal of Zoology 270:132-138.
- Ozgul, A., K. B. Armitage, D. T. Blumstein, D. H. Van Vuren, and M. K. Oli. 2006. Effects of patch quality and network structure on patch occupancy dynamics of a yellow-bellied marmot population. Journal of Animal Ecology 75:191-202.
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Progress 01/01/05 to 12/31/05
Outputs
During 2005, 119 golden-mantled ground squirrels were trapped, ear-tagged, and dye-marked for individual recognition, then tracked through intensive behavioral observations to determine spatial and temporal dynamics. For the third year in a row, densities remained very high. Reproduction was high as well, indicating a lack of density-dependent responses in reproduction, which is perplexing. In the past, early snowmelt has been associated with relatively high reproduction, which in turn leads to increased density. However, time of snowmelt was normal this year, yet the population remained dense and reproduction remained high. The causes for this pattern remain unclear at this point
Impacts
Many species of ground squirrels are considered pests and are threats to agriculture and public health. Designing effective control programs requires information on basic ecology and behavior of the pest species. My results on temporal and spatial dynamics of ground squirrels enhance our knowledge of how pest species respond to environmental factors, allowing managers to design control programs that are more effective at reducing damage by squirrels.
Publications
- Van Vuren, D. H. 2004. Dispersal. pages 988-992 in Encyclopedia of animal behavior, Marc Bekoff, editor. Greenwood Press, Westport, Connecticut.
- Floyd, C. H., D. H. Van Vuren, and B. P. May. 2005. Marmots on Great Basin mountaintops: using genetics to test a biogeographic paradigm. Ecology 86:2145-2153.
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Progress 01/01/04 to 12/31/04
Outputs
During 2004, 123 golden-mantled ground squirrels were trapped, ear-tagged, and dye-marked for individual recognition, then tracked through intensive behavioral observations to determine spatial and temporal dynamics. For the second year in a row, densities increased dramatically; in fact, both density and reproduction this year were the highest ever recorded in this population of squirrels. The causes are unclear at this point. For example, early snow melt can enhance reproduction, but snow melt was not especially early this year. At present, these extraordinarily high numbers seem likely to be the result of multiple factors acting in concert, and that lag effects from factors in previous years come into play.
Impacts
Many species of ground squirrels are considered pests and are threats to agriculture and public health. Designing effective control programs requires information on basic ecology and behavior of the pest species. My results on temporal and spatial dynamics of ground squirrels enhance our knowledge of how pest species respond to environmental factors, allowing managers to design control programs that are more effective at reducing damage by squirrels.
Publications
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Progress 01/01/03 to 12/31/03
Outputs
During 2003, 66 golden-mantled ground squirrels were trapped, ear-tagged, and dye-marked for individual recognition, then tracked through intensive behavioral observations to determine spatial and temporal dynamics. Densities increased dramatically this year, caused primarily by high survival of females overwinter and a very high rate of reproduction by females. This sudden demographic change probably had multiple causes. High reproduction may have resulted from a lag effect, with several females failing to breed the preceding year because of drought. Additionally, a female immigrated into the study area mid-summer and brought her litter with her; I have never observed this phenomenon before (immigrants always come alone, after reproduction, then first breed the following year). The cause of a high overwinter survival is unclear at this time.
Impacts
Many species of ground squirrels are considered pests and are threats to agriculture and public health. Designing effective control programs requires information on basic ecology and behavior of the pest species. My results on temporal and spatial dynamics of ground squirrels enhance our knowledge of how pest species respond to environmental factors, allowing managers to design control programs that are more effective at reducing damage by squirrels.
Publications
- Armitage, K. B., and D. H. Van Vuren. 2003 in press. Individual differences and reproductive success in yellow-bellied marmots. Ethology, Ecology and Evolution.
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Progress 01/01/02 to 12/31/02
Outputs
During 2002, 37 golden-mantled ground squirrels were trapped, ear-tagged, and dye-marked for individual recognition, then tracked through intensive behavioral observations to determine spatial and temporal dynamics. Densities increased somewhat this year, allowing analysis of how home range size and overlap respond to increasing density; they showed little change from the low-density pattern of enlarged home ranges shown in recent years. Further, last spring was exceptionally dry with one of the earliest snow melts on record, providing an opportunity to observe how an early season affects ground squirrel phenology. Surprisingly, the response was bimodal; some females reproduced exceptionally early, but others reproduced at the normal time. I had expected a unified shift to early reproduction.
Impacts
Many species of ground squirrels are considered pests and are threats to agriculture and public health. Designing effective control programs requires information on basic ecology and behavior of the pest species. My results on temporal and spatial dynamics of ground squirrels enhance our knowledge of how pest species respond to environmental factors, allowing managers to design control programs that are more effective at reducing damage by squirrels.
Publications
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Progress 01/01/01 to 12/31/01
Outputs
During 2001 a study of temporal and spatial dynamics of golden-mantled ground squirrels was continued. Twenty-one squirrels were trapped, ear-tagged, and dye-marked for individual recognition. Trap data were used to determine temporal variation in population size, sex ratios, and productivity. Intensive behavioral observations were conducted on all squirrels throughout the summer active season to determine 1) home range size, spatial location, and temporal shifts in location; 2) home range overlap between individuals; 3) behavioral interactions between individuals; and 4) activity budgets.
Impacts
Many species of ground squirrels are considered pests and are threats to agriculture and public health. Designing effective control programs requires information on basic ecology and behavior of the pest species. My results on temporal and spatial dynamics of ground squirrels will allow managers to design control programs that are more effective at reducing damage by squirrels.
Publications
- Van Vuren, D. H. 2001. Predation on yellow-bellied marmots (MARMOTA FLAVIVENTRIS). American Midland Naturalist 145:94-100.
- Kelt, D. A., and Van Vuren, D. H. 2001. The ecology and macroecology of mammalian home range area. American Naturalist 157:637-645.
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Progress 01/01/00 to 12/31/00
Outputs
During 2000 a study of temporal and spatial dynamics of golden-mantled ground squirrels was continued. Fifteen squirrels were trapped, ear-tagged, and dye-marked for individual recognition. Trap data were used to determine temporal variation in population size, sex ratios, and productivity. Intensive behavioral observations were conducted on all squirrels throughout the summer active season to determine 1) home range size, spatial location, and temporal shifts in location; 2) home range overlap between individuals; 3) behavioral interactions between individuals; and 4) activity budgets.
Impacts
Many species of ground squirrels are considered pests and are threats to agriculture and public health. Designing effective control programs requires information on basic ecology and behavior of the pest species. My results on temporal and spatial dynamics of ground squirrels will allow managers to design control programs that are more effective at reducing damage by squirrels.
Publications
- Kelt, D. A., and Van Vuren, D. 1999. Energetic constraints and the relationship between body size and home range area in mammals. Ecology 80:337-340.
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Progress 01/01/99 to 12/31/99
Outputs
During 1999 a study of temporal and spatial dynamics of golden-mantled ground squirrels was continued. Twenty-four squirrels were trapped, ear-tagged, and dye-marked for individual recognition. Trap data were used to determine temporal variation in population size, sex ratios, and productivity. Intensive behavioral observations were conducted on all squirrels throughout the summer active season to determine 1) home range size, spatial location, and temporal shifts in location; 2) home range overlap between individuals; 3) behavioral interactions between individuals; and 4) activity budgets.
Impacts
Many species of ground squirrels are considered pests and are threats to agriculture and public health. Designing effective control programs requires information on basic ecology and behavior of pest species. My results on temporal and spatial dynamics of ground squirrels will allow managers to design control programs that are more effective at reducing damage by squirrels.
Publications
- Van Vuren, D. 1998. Manipulating habitat quality to manage vertebrate pests. Proc. Vertebrate Pest Conf. 18:383-390.
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Progress 01/01/98 to 12/01/98
Outputs
During 1998 a study of temporal and spatial dynamics of golden-mantled ground squirrels was continued. Ninety-three squirrels were trapped, ear-tagged, and dye-marked for individual recognition. Trap data were used to determine temporal variation in population size, sex ratios, and productivity. Intensive behavioral observations were conducted on all squirrels throughout the summer active season to determine: 1) home range size, spatial location, and temporal shifts in location; 2) home range overlap between individuals; 3) behavioral interactions between individuals; and 4) activity budgets.
Impacts
(N/A)
Publications
- SCHWARTZ, O. A., ARMITAGE, K. B., and VAN VUREN, D. 1998. A 32-year demography of yellow-bellied marmots (MARMOTA FLAVIVENTRIS). Journal of Zoology 246:337-346.
- VAN VUREN, D. 1998. Mammalian dispersal and reserve design. Pages 369-393 in: Behavioral ecology and conservation biology (Tim Caro, editor). Oxford University Press, New York.
- KUENZI, A. J., LYNCH, M., VAN VUREN, D., LOREDO, I., and MORRISON, M. L. 1998. Diets of three predators at Concord Naval Weapons Station, Contra Costa County, California. Northwestern Naturalist 79:64-67.
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Progress 01/01/97 to 12/01/97
Outputs
During 1997 a study of temporal and spatial dynamics of golden-mantled ground squirrels was continued. Seventy-seven squirrels were trapped, ear-tagged, and dye-marked for individual recognition. Trap data were used to determine temporal variation in population size, sex ratios, and productivity. Intensive behavioral observations were conducted on all squirrels throughout the summer active season to determine: 1) home range size, spatial location, and temporal shifts in location; 2) home range overlap between individuals; 3) behavioral interactions between individuals; and 4) activity budgets.
Impacts
(N/A)
Publications
- VAN VUREN, D., KUENZI, A. J., LOREDO, I., LEIDER, A. L., AND MORRISON, M. L. 1997. Translocation as a nonlethal alternative for managing California ground squirrels. Journal of Wildlife Management
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Progress 01/01/95 to 12/30/95
Outputs
During 1995 a study of dispersal of yellow-bellied marmots was concluded. Six marmots that were equipped with radio transmitters were radio located; three were killed by predators, and three survived. Research on temporal and spatial dynamics of golden-mantled ground squirrels was continued. Seventy-one squirrels were trapped, ear-tagged, and dye-marked for individual recognition. Trap data were used to determine population size, sex ratios, and productivity. Through a combination of trapping and observation, locations of squirrels were plotted to determine size and location of home ranges. Behavioral observations were used to determine temporal changes in activity budgets of squirrels, and to record behavioral interactions between squirrels.
Impacts
(N/A)
Publications
- LENIHAN, C. and VAN VUREN, D. Growth and survival of juvenile yellow-bellied marmots (MARMOTA FLAVIVENTRIS). Canadian Journal of Zoology. In press.
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Progress 01/01/94 to 12/30/94
Outputs
I continued my research on yellow-bellied marmots and discovered the following: 1) Dispersal occurs earlier than previously thought. Marmots typically emigrate early or mid-summer when 1 year old; some juveniles, however, emigrate late in the summer when only 2 months old. 2) Dispersal distance of females is longer than previously thought. 3) Survival of female dispersers, especially the year after dispersing, is higher than previously thought. I initiated a new study on golden-mantled ground squirrels. Juveniles disperse within a few weeks after weaning and move surprisingly long distances. Rate of dispersal is much higher than in yellow-bellied marmots. I also initiated two new studies on California ground squirrels, one to determine the efficacy of translocation as a nonlethal control method, the other to evaluate a suspected commensal relationship between this species and the California tiger salamander, a protected species. Survival of translocated squirrels is
high, but many squirrels could find their way back home, and most of the remaining survivors settle away from the release site. Tiger salamanders move substantial distances when dispersing from their breeding ponds and almost all, as suspected, do select ground squirrel burrows as terrestrial habitat. Because of this commensal relationship, tiger salamanders may be threatened by ground squirrel control programs.
Impacts
(N/A)
Publications
- VAN VUREN, D., AND ARMITAGE, K. B. 1994. Survival of dispersing and philopatric yellow-bellied marmots: what is the cost of dispersal. Oikos 69:179-181.
- VAN VUREN, D., AND ARMITAGE, K. B. 1994. Reproductive success of colonial and noncolonial female yellow-bellied marmots (MARMOTA FLAVIVENTRIS). J. Mamm 75:950- 955.
- LOREDO-PRENDEVILLE, I., VAN VUREN, D., KUENZI, A. J., AND MORRISON, M. L. 1994. Calif. ground squirrels at Concord Naval Weapons Sta.: alternatives for control and the ecological consequences. Proc. Vertebr. Pest Conf. 16:72-77.
- LENIHAN, C. 1995. Cost and benefits of sociality in yellow- bellied marmots (MARMOTA FLAVIVENTRIS): do noncolonial females have lower fitness. M.S. Thesis.
- LOREDO-PRENDEVILLE, I. 1995. Reproductive ecology, microhabitat use, and migration behavior of the California tiger salamander. M.S. Thesis.
- VAN VUREN, D. 1991. Yellow-bellied marmots as prey of coyotes. Amer. Midl. Nat. 125:135-139.
- VAN VUREN, D., AND ARMITAGE, K. B. 1991. Duration of snow cover and its influence on life-history variation in yellow- bellied marmots. Can. J. Zoo. 69:1755-1758.
- VAN VUREN, D., AND SALSBURY, C. M. 1992. The relation between premolar wear and age in yellow-bellied marmots, MARMOTA FLAVIVENTRIS. Can. Field-Nat. 106:134-136.
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Progress 01/01/93 to 12/30/93
Outputs
During 1993 a study of dispersal of yellow-bellied marmots was continued. Eighteen marmots were equipped with radio-transmitters before dispersal began; three were killed by predators during dispersal, and six survived dispersal and entered hibernation. Nine marmots did not disperse. Research on social organization and dispersal of golden-mantled ground squirrels also was continued. Sixty-four squirrels were trapped, ear-tagged, and dye-marked for individual recognition. After release, squirrels were observed visually to determine home range size and overlap, and interactions with other squirrels.
Impacts
(N/A)
Publications
- VAN VUREN, D. and ARMITAGE, K.B. 1994. Survival of dispersing and philopatric yellow-bellied marmots: what is the cost of dispersal. Oikos. Accepted for publication.
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Progress 01/01/92 to 12/30/92
Outputs
During 1992 a study of dispersal of yellow-bellied marmots was continued. Twenty-one marmots were equipped with radio-transmitters before dispersal began; eight were killed by predators during dispersal, and the remaining 13 survived to enter hibernation. Research on social organization and dispersal of golden-mantled ground squirrels also was continued. Forty-six squirrels were trapped, ear-tagged, and dye-marked for individual recognition. After release, squirrels were observed visually to determine home range size and overlap, and interactions with other squirrels.
Impacts
(N/A)
Publications
- No publications reported this period.
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Progress 01/01/91 to 12/30/91
Outputs
During 1991 a study of dispersal of yellow-bellied marmots was continued. Twenty-eight marmots were equipped with raddio-transmitters before dispersal began; six were killed by predators during dispersal, and the remaining 22 survived to enter hibernation. Research on social organization and dispersal of golden-mantled ground squirrels also was continued. Thirty-six squirrels were trapped, ear-tagged, and dye-marked for individual recognition. After release, squirrels were observed visually to determine home range size and overlap, and interactions with other squirrels.
Impacts
(N/A)
Publications
- VAN VUREN, D. and SALSBURY, C.M. 1992. The relation between premolar wear and age in yellow-bellied marmots, MARMOTA FLAVIVENTRIS. Canadian Field-Naturalist. Accept for pub.
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Progress 01/01/90 to 12/30/90
Outputs
During 1990 the first phase was completed of a study of dispersal of yellow-bellied marmots: determining dispersal distance and survival of dispersers until one year after dispersal. The second phase of the study then was initiated: determining survival of dispersing marmots from one to two years after dispersal. Radio-transmitters were affixed to 42 marmots before dispersal began; 28 subsequently dispersed. Of these, 21 survived dispersal and entered hibernation. The remaining seven were killed by predators during dispersal. Concurrently, a study of social organization and dispersal of golden-mantled ground squirrels was initiated. An appropriate study population was selected, and all adults (19 males and 18 females) and juveniles (6 males and 10 females) were livetrapped, weighed, sexed, and individually marked. Visual observations to determine social interactions and home range size and location were begun.
Impacts
(N/A)
Publications
- VAN VUREN, D. 1991. Yellow-bellied marmots as prey of coyotes. American Midland Naturalist. 125:135-139.
- VAN VUREN, D., and ARMITAGE, K.B. 1991. Duration of snow cover and its influence on life-history variation in yellow-bellied marmots. Canadian Journal of Zoology. 69:In Press.
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