An Analysis of Harbor Seal ( Phoca Vitulina ) and Gray Seal ( Halichoerus Grypus ) Haul-out Patterns, Behavior Budgets, and Aggressive Interactions on Mount Desert Rock, Maine
As gray seal (Halichoerus gypus) populations continue to grow in the Gulf of Maine, it is necessary to quantie changes to the regional ecology for both management and conservation purposes. This study compares haul-out patterns, presents summer activity budgets, and contrasts intra- and interspecifi...
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| Format: | Text |
| Language: | unknown |
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DigitalCommons@UMaine
2005
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| Online Access: | https://digitalcommons.library.umaine.edu/etd/1542 https://digitalcommons.library.umaine.edu/cgi/viewcontent.cgi?article=2571&context=etd |
| Summary: | As gray seal (Halichoerus gypus) populations continue to grow in the Gulf of Maine, it is necessary to quantie changes to the regional ecology for both management and conservation purposes. This study compares haul-out patterns, presents summer activity budgets, and contrasts intra- and interspecific aggressive interactions among the harbor seal (Phoca vitulina) and gray seal population on Mount Desert Rock, Maine. These data were collected using Altman's scan method and focal animal sampling. Time to low tide and day of year influenced both harbor seal and gray seal haul-out patterns on Mount Desert Rock. For both species, more seals hauled-out closer to low tide. Day of year was correlated positively with numbers of harbor seals and negatively with numbers of gray seals. Overall activity budgets are presented for both species; the harbor seal budget agrees well with previously published data and the gray seal budget is the first documented for this species during summer months, but is generally similar to winter breeding season budgets. Intrinsic and environmental factors influenced harbor seal behavior patterns. Gray seals had little, if any, effect on harbor seal behavior patterns and were only important in one of three models describing harbor seal sleep budgets. Harbor seal behavior budgets and rates were most broadly-affected by number of adjacent seals. At moderate densities of 3-5 adjacent seals, focal harbor seals slept more in longer, fewer bouts, while reducing overall time scanning via fewer bouts. Sleep budgets were also positively correlated with total number of seals on a haul-out ledge, day of year, wind speed, and cloud cover and negatively correlated with absolute time to low tide and air temperature. Sleep bouts occurred more frequently during higher tides and during calm wind conditions. Scanning budgets were positively correlated with higher tide states and the absence of fog and negatively correlated with number of seals on a ledge, wind speed, day of year, and cloud cover. Harbor seal ... |
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