Progress 07/15/00 to 07/14/04
Outputs
A total of 37 male deer were captured for sterilization. The sterilization technique was tested on tranquilized bucks, where a sclerosing agent was injected directly into each cauda epididymis, thus blocking the flow of sperm. Semen was collected from the animal before treatment. Previously treated animals were captured opportunistically throughout the study. Ten males were captured and sterilized in 2003 and 1 thus far in 2004, bringing the total number of sterilized males on the study site to 37. Eight previously sterilized males were recaptured throughout the study. Semen analyses of these individuals have shown that treated males remain sterile; however, sperm were present in low abundance in one animal sterilized 3 years previous. Field observations of treated bucks during the breeding season indicate they continue to engage in mating and mate-guarding behavior. Though treated animals remain sterile, a population decline as a result of treatment was not observed
during the study. Possible reasons for a lack of response include: a large study area, increased immigration and emigration rates of males, and limited capture of breeding age males. This technique may have the most potential when used in concert with female reproductive control efforts or on a site insular in nature to reduce ingress and egress of male deer. Numerous repellent trials have been ongoing. A wireless deer fence that attracts deer with an odor and then delivers an electrical stimulation was effective at preventing damage in an orchard from 2000-2001, but lost its effectiveness afterward. A taste based repellent, DeerStopper, was tested by applying to a rope surrounding the plot, and reapplying every 2 weeks. Two treatment plots and 2 control plots were established in the orchard. Trees enclosed in the rope treatment went from 46% browsed stems to 7% in one month, while the control plots showed an increase from 47% to 67%. Because of the success of the trial, other
researchers used the technique. It then became ineffective as deer became habituated. Surveys and informal interviews sent to members of the Connecticut Farm Bureau, Connecticut Nursery and Landscape Association, and fruit growers determined that fencing was near 100% effective. If fencing is not an option, it was found that if multiple types of repellents are used in a biweekly rotation, they remain potent and deer are less likely to become habituated to them. Approximately 125 animals have been captured and marked to date. Utilizing visual observations, radio telemetry, and GPS technology, movements of deer through suburban neighborhoods and adjacent woodlands were monitored. Deer generally utilized residents' backyards during evening and night hours and retreated to the cover of adjacent woodlands during daylight. Damage to shrubs, gardens, and landscape plantings most often occurred during night hours. Deer on the periphery of the study area tended to establish winter home ranges
an average of 330 meters closer to residences than summer ranges as landscape and ornamental plantings provide a year-round food source.
Impacts
The need for non-lethal population control has grown over the past two decades as a decline in hunting and an increase in urbanization have combined to create a large white-tailed deer population. The long-term goal of the deer sterilization study is to provide a non-lethal technique to control population growth. If successful, this technique has applications to deer population control efforts in areas of high human and deer densities. Deer damage to cultivated crops and landscape plantings are substantial, and the studies that examine the effectiveness of different repellents will provide growers and homeowners more options to reduce deer damage. The long-term benefit of this research will be less deer damage to cultivated crops and landscape plantings.
Publications
- Ramakrishnan, U. and S. C. Williams. 2003. Buck sterilization as a potential white-tailed deer population control technique. The 59th Annual Northeast Fish and Wildlife Conference. April 13-16. Newport, Rhode Island, USA.
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Progress 01/01/03 to 12/31/03
Outputs
This progress report includes the following topics:(1)Fertility Control of White-tailed Deer;(2) Measuring changes in population size and birth rate; and (3) Evaluation of deer repellents. In 2001 sixteen male deer were captured for sterilization. The sterilization technique was tested on tranquilized bucks, where a sclerosing agent was injected directly into each cauda epididymis, thus blocking the flow of sperm. Semen was collected from the animal before treatment and a few days following treatment. Ten males have been captured and sterilized in 2002, bringing the total number of sterilized males on the study site to 26 males. Four males treated in 2001 were recaptured in 2002, and semen analyses of these treated individuals have shown that the treated males are still sterile. Field observations of treated bucks during the 2003-2004 breeding season indicate that the treated animals continue to engage in mating and mate-guarding behavior. Treated bucks will be
captured every year to test for the presence of sperm. Males will continue to be captured until the end of the breeding season in late February. Untreated males will be captured to be treated, treated males will be recaptured to check for the longevity of the sterilization technique. To measure the success of the sterilization technique in reducing the population growth rate, the number of fawns born in 2002 was recorded using both direct sightings and infrared cameras placed at feeders. In 2000-2001, a wireless fence was evaluated for the protection of an apple orchard at Lockwood farm that had previously been heavily browsed by deer. The commercially available device, called the wireless deer fence, contained an odor-based deer attractant that administers a shock on contact. Twenty-one units were placed at 20 ft intervals along the periphery of the orchard. The repellent appeared effective for the first year, with a noticeable decrease in browse damage. However, it lost its
effectiveness by the end of the first year, and deer damage became apparent. The wireless deer fence was removed in May 2002, and the effectiveness of another repellent, the DeerStopper, is currently being evaluating at the same apple orchard. The active ingredients in the repellent are mint oil, rosemary oil and salt. The orchard was divided into 2 control plots and 2 treatment plots, with 70 trees in the treatment plot and 80 trees in the control plot. In the treatment plots, the repellent mixture was sprayed onto a half inch thick nylon rope, and the rope was fixed to stakes that enclosed the plot. The height and number of browsed branches are recorded each month. Before treatment, 45.61 percent of the branches in the treatment plot and 46.67 percent of the branches in the control plot had been browsed. After 1 month of treatment, 7.29 percent of the branches in the treatment plot and 67.14 percent of the branches in the control plot had been browsed. Trees in the treated plots
also recorded a 19.79 percent increase in overall height in 1 month compared to trees in the control plots that increased by 8.96 percent.
Impacts
The need for non-lethal population control has grown over the past two decades as a decline in hunting and an increase in urbanization have combined to create a large white-tailed deer population. The long-term goal of the deer sterilization study is to provide a non-lethal technique to control population growth. If successful, this technique has applications to deer population control efforts in areas of high human and deer densities. Deer damage to cultivated crops and landscape plantings are substantial, and the studies that examine the effectiveness of different repellents will provide growers and homeowners more options to reduce deer damage. The long-term benefit of this research will be less deer damage to cultivated crops and landscape plantings.
Publications
- No publications reported this period
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Progress 01/01/02 to 12/31/02
Outputs
This progress report includes the following topics:(1)Fertility Control of White-tailed Deer;(2)Measuring changes in population size and birth rate; and(3)Evaluation of deer repellents. In 2001 sixteen male deer were captured for sterilization. The sterilization technique was tested on tranquilized bucks, where a sclerosing agent was injected directly into each cauda epididymis, thus blocking the flow of sperm. Semen was collected from the animal before treatment and a few days following treatment. Ten males have been captured and sterilized in 2002, bringing the total number of sterilized males on the study site to 26 males. Four males treated in 2001 were recaptured in 2002, and semen analyses of these treated individuals have shown that the treated males are still sterile. Field observations of treated bucks during this year's breeding season indicate that the treated animals continue to engage in mating and mate-guarding behavior. Males will continue to be
captured until the end of the breeding season in late February - untreated males will be captured to be treated, treated males will be recaptured to check for the longevity of the sterilization technique. To measure the success of the sterilization technique in reducing the population growth rate, the number of fawns born in 2002 was recorded using both direct sightings and infrared cameras placed at feeders. In 2000-2001, a wireless fence was evaluated for the protection of an apple orchard at Lockwood farm that had previously been heavily browsed by deer. The commercially available device, called the wireless deer fence, contained an odor-based deer attractant and administers a shock on contact. Twenty-one units were placed at 20 ft intervals along the periphery of the orchard. The repellent appeared effective for the first year, with a noticeable decrease in browse damage. However, it lost its effectiveness by the end of the first year, and deer damage became apparent. The wireless
deer fence was removed in May 2002, and the effectiveness of another repellent, the Deer-Stopper, is currently being evaluating at the same apple orchard. The active ingredients in the repellent are mint oil, rosemary oil and salt. The orchard was divided into 2 control plots and 2 treatment plots, with 70 trees in the treatment plot and 80 trees in the control plot. In the treatment plots, the repellent mixture was sprayed onto a half inch thick nylon rope, and the rope was fixed to stakes that enclosed the plot. The height and number of browsed branches are recorded each month. Before treatment, 45.61 percent of the branches in the treatment plot and 46.67 percent of the branches in the control plot had been browsed. After 1 month of treatment, 7.29 percent of the branches in the treatment plot and 67.14 percent of the branches in the control plot had been browsed. Trees in the treated plots also recorded a 19.79 percent increase in overall height in 1 month compared to trees in the
control plots that increased by 8.96 percent.
Impacts
The need for non-lethal population control has grown over the past two decades as a decline in hunting and an increase in urbanization have combined to create a large white-tailed deer population. The long-term goal of the deer sterilization study is to provide a non-lethal technique to control population growth. If successful, this technique has applications to deer population control efforts in areas of high human and deer densities. Deer damage to cultivated crops and landscape plantings are substantial, and the studies that examine the effectiveness of different repellents will provide growers and homeowners more options to reduce deer damage.
Publications
- No publications reported this period
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Progress 01/01/01 to 12/31/01
Outputs
This project includes the following topics: (1) Fertility Control of White-tailed Deer (2) Measurement of Deer Browse Damage; and (3) Effort, economics and accuracy of different methods of estimating deer population size in suburbia. Between September 2000 and December 2001, 70 male and female deer were captured and fitted with cattle tags for individual identification. Some of the animals were also fitted with radio or GPS collars to monitor age-structure and movement patterns of deer at the study site. The proportion of fawns born in 2000-2001 in relation to the proportion of adult females in the site was recorded at 1 fawn to 3.5 females. The proportion of fawns born in 2001-2002 is currently being monitored. Sterilization of males began in October 2001, using a technique to block the epididymus, thus preventing the flow of sperm and causing sterility. This technique has been used on domestic animals but has not been applied to deer. So far, 15 bucks (60% of
planned total) have been sterilized. The number of fawns born in 2002 and 2003 will be compared with the proportion of fawns born the previous two years, to measure success of the sterilization technique. To measure browse damage, eighteen 10x10 m plots were set up throughout Lake Gaillard in April 2001. Nine of the plots are protected with fencing that excludes deer, 9 others are unprotected, allowing deer access to the plots. The diameter at breast height (dbh) and species of all trees (stems > 9 cm dbh) were identified to establish relative tree density and dominance within each plot. All saplings (stems > 1 cm and < 9 cm dbh) inside the plots were also identified and tagged. Within each plot, the number of twigs on each sapling between 0 and 1.25 m above the ground were counted. Four techniques for estimating deer population size are being compared at Lake Gaillard. The techniques being tested are - road count; mark-recapture technique; line-transect technique and aerial count.
Data collection began on July 15th 2000. This included 12 walking transects, 6 vehicle transects and 10 baiting sites fitted with infrared-triggered motion-sensitive cameras for the mark-recapture technique. Data analysis comparing 3 techniques - the road counts, mark-recapture counts and line-transect counts, has revealed that the mark-recapture technique required substantial effort and expense to conduct. Vehicle counts had the advantage of requiring the least effort and cost, but were not accurate when conducted on moderate to heavily used roads. Of the three techniques, the walking transects appeared to be the most appropriate technique to estimate deer population size in a suburban community, because it provided the most accurate results at the lowest cost and least effort. The population estimates and age structure derived from the different techniques are also being used to design the fertility control program. The aerial count will be conducted in January 2002.
Impacts
Increased urbanization has amplified the need for non-lethal methods of controlling deer population growth. The sterilization technique being tested in this study is permanent, easy to perform, requires no surgical equipment, and has been used successfully on other species. By targeting large males with established territories, fewer numbers of individuals need to be treated, thus reducing the costs of a sterilization program.
Publications
- No publications reported this period
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Progress 01/01/00 to 12/31/00
Outputs
The project has three major objectives: (1) to compare the cost, effort and accuracy of three deer density estimation methods (2) to quantify seasonal browse damage by white-tailed deer in different habitat types; and (3) to record seasonal changes in habitat use and movement patterns of white-tailed deer. Data collection to estimate white-tailed deer densities at Lake Gaillard began on July 15th 2000. This includes 12 walking transects, 2 vehicle transects and 10 baiting sites fitted with infrared-triggered motion-sensitive cameras. The Connecticut Department of Environmental Protection issued a permit authorizing the baiting, darting, collaring and tagging of white-tailed deer at the study site, and since then, 36 deer have been captured and fitted with ear-tags for identification. In addition, 6 deer have been fitted with GPS-collars and 12 deer have been fitted with radio-collars. The movement of collared deer are being monitored.
Impacts
The study comparing deer density estimation methods will provide managers with effective alternatives to calculate suburban deer population size. Knowledge of the habitat preferences of deer within their home-range, as well as seasonal changes in habitat use and distribution will provide managers with information that can be used to reduce the negative impacts of deer in and around residential communities.
Publications
- No publications reported this period
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