Responses of molting Pacific black brant to experimental aircraft disturbance in the Teshekpuk Lake Special Area, Alaska /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1990.
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| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | Responses of Pacific black brant (Branta bernicla nigricans) to experimental aircraft disturbances were studied in the Teshekpuk Lake Special Area (TLSA), Alaska, 1987-89. Up to 25% of the population of Pacific black brant annually use the TLSA as a molting area. During molt brant spent 88.6% of the time in feeding, resting, or maintenance behaviors. Behavioral patterns were distributed bimodally on a daily basis, with resting peaking between 0000 and 0400 hours and feeding peaking between 0400 and 0800 hours. Data suggest that the amount of time that brant can feed may be restricted by a variety of factors including gut capacity and forage digestibility. Telemetry locations of radio-marked brant indicated that there were no differences in the rates of movement between sex and age classes. However, brant at East Long Lake (ELL) moved at over twice the rate of birds at Island Lake (IL). Possible explanations for differential movement rates between lakes included the relative position and distribution of favored habitats around each lake; and the difference in the size of molting populations at each lake which would affect interspecific competition for forage. Radioed brant exhibited 100% survival during the molt period. Low morality of brant in the TLSA during the molting period was suggested as a mechanism for the traditional use of molting areas. Analysis of the vegetative characteristics of habitats used by radio-marked brant indicated that they selected areas dominated by hydrophytic graminoids and forbs. Diversity indices indicated that habitats used by brant were floristically simpler than nonuse areas. The use areas were low-relief shorelines offering maximum visibility, abundant forage, and an avenue of quick escape to water or ice floes. Responses of brant to experimental overflight disturbances by Bell 206 helicopters indicated that aircraft would have to fly above 1,070 m to have no significant (P > 0.05) affect on the behavior of the birds. The average altitude of helicopters incidentally flying through the study area was 330 m. The response duration of brant varied also with the lateral distance from the aircraft to the flock. Large flocks (>100) of brant tended to react longer to disturbances than small flocks. Molting brand did not habituate to repeated aircraft disturbances on either a daily or yearly basis. Comparisons of movement rates of radioed brant between the experimental (ELL) and control (IL) study sites revealed that brant exposed to helicopter disturbances moved at over 5 times the rate of undisturbed birds. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Wildlife and fisheries sciences." |
| Physical Description: | x, 72 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |