Escorting of Mother-Calf Pairs of Humpback Whales ( Megaptera novaeangliae ) in the Colombian Pacific during the Breeding Season
Humpback whales (Megaptera novaeangliae) belonging to the “breeding G-stock” annually migrate from the Antarctic Peninsula and southern Chile to the southeastern Pacific to reproduce. Associations between mother-calf pairs and escorts were examined in the Gulf of Tribugá, northern Colombian Pacific,...
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| Language: | unknown |
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The Aquila Digital Community
2017
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| Online Access: | https://aquila.usm.edu/dissertations/1486 https://aquila.usm.edu/context/dissertations/article/2521/viewcontent/auto_convert.pdf |
| Summary: | Humpback whales (Megaptera novaeangliae) belonging to the “breeding G-stock” annually migrate from the Antarctic Peninsula and southern Chile to the southeastern Pacific to reproduce. Associations between mother-calf pairs and escorts were examined in the Gulf of Tribugá, northern Colombian Pacific, using photo-identification and behavioral/spatial sampling. Research hypotheses included: 1. The association between cows and escorts is short-lived, consistent with a male reproductive strategy, 2. The presence of escort(s) elicits a behavioral response from mother-calf pairs and, 3. The patterns of spatial distribution reflect the spatial segregation of maternal females. Groups were classified as mother-calf pairs (Mc), mother, calf and escort (McE), and mother, calf and multiple escorts (McME). Sightings were made in 2010 and between 2013 and 2016. Photo-identification procedures included comparisons of the caudal and dorsal fins. For each group, coordinates were processed in ArcMap v10.3, extracting depth and distance to the coast. Speed data was calculated using Basecamp v4.6. Tracks were classified as traveling or milling based on directionality and trajectory. Spatial variables were processed with multivariate and factorial analyses of variance. Chi-squared tests compared behavioral frequencies across group types. Groups with calves (n=108) represented 20.7% of all sightings. While a total of 15 re-sightings were recorded, they were limited to changes in group composition or separate encounters with either the cow or the escort(s). Escorted pairs spent significantly more time traveling and executing surface-active and social behaviors. Additionally, they spent less time diving and resting when compared to unescorted pairs (χ28>15.51, p0.05. Similarly, the factorial ANOVA indicated that traveling speeds were not significantly different when compared across date or group/track types F(3, 61) = 0.860, p>0.05. In conclusion, in the Gulf of Tribugá, associations between cows and escorts seem to be transitory, ... |
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