Graduate Thesis Or Dissertation
 

Home range, dispersal, homing and density of the Townsend mole Scapanus townsendii (Bachman) near Tillamook, Oregon

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  • Home range, dispersal, homing and density of Townsend's mole, Scapanus townsendii (Bachman), were studied during 1964 near Tillamook, Oregon. Additional information on the success of marking and capture techniques and the response of moles to flooding was gathered. This study was initiated to supply information which might aid in the modification or development of mole control and eradication techniques. Live trapping and capturing with the aid of a shovel were moderately successful methods of obtaining live moles during the study, but were not satisfactory for detailed studies of local movements. Monel metal bands 19 x 3.4 x 0.5 mm., attached to the hind leg just above the heel, proved satisfactory for marking adult and sub-adult live moles. Data on local movements were obtained from 176 live captures involving 116 moles. The mean distance between the widest points of capture for 14 individuals of both sexes captured three or more times each within the home range was 133 feet. Greater range lengths were recorded from poorly-drained pasture areas of lower population density, while shorter range lengths occurred in well-drained soils of higher population density. Recapture records of adult moles indicated that home ranges were fairly stable and discrete. To study the dispersal of juvenile moles from their birthplaces, a total of 180 young from 62 nests were marked by toe clipping and returned to the nest. An estimated maximum of 122 of these young survived and matured to dispersal age. A four month period was allowed for young to scatter, after which an intensive dead trapping program was initiated in an attempt to recapture the marked young. Forty-four (36 percent) of the 122 were recaptured, Ninety percent of the males and 84 percent of the females had travelled less than 1000 feet from their birthplace. Considering both sexes, 87 percent had travelled less than 1000 feet and 61 percent less than 500 feet. The maximum dispersal distance for a female was 2,808 feet, while that for a male was 2,369 feet. Results from an analysis of 724 barn owl pellets collected at monthly intervals during 1964 showed a significant number of juvenile moles were taken between May and July. This evidence indicates that some dispersal of juvenile moles takes place on the surface of the ground at night. Homing was successful for 17 of 36 individuals displaced different distances and across different barriers. Nine of 11 moles successfully returned where no physical barrier to movement was present. Seven of 12 individuals returned across a water-filled drainage canal; one of five returned across an elevated major highway; and one of eight returned across a river. Four of the moles returning over open terrain had been displaced by flooding. Homing behavior is believed to partially explain the rapid reinvasion of stream bottom lands after flooding. The density of moles on the study area ranged from 0.17 to 5.4 per acre and averaged 2.2 per acre. Severe flooding was found to result in significant mortality of moles in the Tillamook area. Poor eyesight is believed to be a major factor in the failure of moles to escape flood waters.
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file details GigerRichardDee1965.pdf 2017-08-08 Público Descargar