Isolating bias in association indices

Weko, Charles

doi:10.1016/j.anbehav.2018.03.011

Cited by 10 publications

(5 citation statements)

References 37 publications

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“…Assuming, quite reasonably, that grouping sets the stage for social interactions to occur (Whitehead & Dufault, 1999), such indices are widely used to portray and test social patterns across animal taxa (Farine & Whitehead, 2015;Whitehead, 2008). However, the literal translation of this metric-the proportion of time individuals were seen together-is subjected to sampling biases (Hoppitt & Farine, 2018;Weko, 2018) and overlooks the multiple underlying factors that can cause aggregation (Whitehead & James, 2015). We show that a coarse association measure (HWI) would suggest prevalent social preferences among individual giraffes; that is, many pairs of individuals spend high proportions of time together.…”

Section: Discussionmentioning

confidence: 97%

Giraffe social preferences are context dependent

2018

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Section: Discussionmentioning

confidence: 97%

Giraffe social preferences are context dependent

2018

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“…The prevalence of social relationships among catalogued fin whales was characterized using weighted association indices. We selected the Simple Ratio association Index (SRI, [81]) because 1) we lacked calibration data and 2) the biases inherent to the SRI are more predictable than to an alternative such as the Half-Weight Index (after [82,83]). The stability of social associations was assessed with randomization, in which the individuals within each encounter were shuffled in the dataset, preserving the number of times each individual was seen, and encounter rates for all possible dyads were recorded.…”

Section: Plos Onementioning

confidence: 99%

Fin whales of the Great Bear Rainforest: Balaenoptera physalus velifera in a Canadian Pacific fjord system

et al. 2021

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Fin whales (Balaenoptera physalus) are widely considered an offshore and oceanic species, but certain populations also use coastal areas and semi-enclosed seas. Based upon fifteen years of study, we report that Canadian Pacific fin whales (B. p. velifera) have returned to the Kitimat Fjord System (KFS) in the Great Bear Rainforest, and have established a seasonally resident population in its intracoastal waters. This is the only fjord system along this coast or elsewhere in which fin whales are known to occur regularly with strong site fidelity. The KFS was also the only Canadian Pacific fjord system in which fin whales were commonly found and killed during commercial whaling, pointing to its long-term importance. Traditional knowledge, whaling records, and citizen science databases suggest that fin whales were extirpated from this area prior to their return in 2005–2006. Visual surveys and mark-recapture analysis documented their repopulation of the area, with 100–120 whales using the fjord system in recent years, as well as the establishment of a seasonally resident population with annual return rates higher than 70%. Line transect surveys identified the central and outer channels of the KFS as the primary fin whale habitat, with the greatest densities occurring in Squally Channel and Caamaño Sound. Fin whales were observed in the KFS in most months of the year. Vessel- and shore-based surveys (27,311 km and 6,572 hours of effort, respectively) indicated regular fin whale presence (2,542 detections), including mother-calf pairs, from June to October and peak abundance in late August–early September. Seasonal patterns were variable year-to-year, and several lines of evidence indicated that fin whales arrived and departed from the KFS repeatedly throughout the summer and fall. Additionally, we report on the population’s social network and morphometrics. These findings offer insights into the dynamics of population recovery in an area where several marine shipping projects are proposed. The fin whales of the Great Bear Rainforest represent a rare exception to general patterns in this species’ natural history, and we highlight the importance of their conservation.

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“…The prevalence and stability of social relationships were characterized using weighted association indices and Lagged Association Rates (LARs). We selected the Simple Ratio association Index (SRI, [ 102 ]) because 1) we lacked calibration data and 2) the biases inherent to the SRI are more predictable than to an alternative such as the Half-Weight Index [ 103 , 104 ]. Based on our fieldwork, we were confident that all adult individuals in groups were identified in nearly all cases, and that exceptions to this were the result of specific circumstances, such as a sudden change in weather, not patterns of certain individuals or social scenarios.…”

Section: Methodsmentioning

confidence: 99%

Social survival: Humpback whales (Megaptera novaeangliae) use social structure to partition ecological niches within proposed critical habitat

Wray¹,

Keen²,

O’Mahony³

2021

PLoS ONE

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Animal culture and social bonds are relevant to wildlife conservation because they influence patterns of geography, behavior, and strategies of survival. Numerous examples of socially-driven habitat partitioning and ecological-niche specialization can be found among vertebrates, including toothed whales. But such social-ecological dynamics, described here as ‘social niche partitioning’, are not known among baleen whales, whose societies—particularly on foraging grounds—are largely perceived as unstructured and incidental to matters of habitat use and conservation. However, through 16 years of behavioral observations and photo-identifications of humpback whales (Megaptera novaeangliae) feeding within a fjord system in the Canadian Pacific (primarily within Gitga’at First Nation waters), we have documented long-term pair bonds (up to 12 years) as well as a complex societal structure, which corresponds closely to persistent patterns in feeding strategy, long-term site fidelity (extended occupancy and annual rate of return up to 75%), specific geographic preferences within the fjord system, and other forms of habitat use. Randomization tests of network congruency and clustering algorithms were used to test for overlap in patterns of social structure and habitat use, which confirmed the occurrence of social niche partitioning on the feeding grounds of this baleen whale species. In addition, we document the extensive practice of group bubble net feeding in Pacific Canada. This coordinated feeding behavior was found to strongly mediate the social structure and habitat use within this humpback whale society. Additionally, during our 2004–2019 study, we observed a shift in social network structure in 2010–2012, which corresponded with environmental and demographic shifts including a sudden decline in the population’s calving rate. Our findings indicate that the social lives of humpback whales, and perhaps baleen whales generally, are more complex than previously supposed and should be a primary consideration in the assessment of potential impacts to important habitat.

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Isolating bias in association indices

Cited by 10 publications

References 37 publications

Giraffe social preferences are context dependent

Giraffe social preferences are context dependent

Fin whales of the Great Bear Rainforest: Balaenoptera physalus velifera in a Canadian Pacific fjord system

Social survival: Humpback whales (Megaptera novaeangliae) use social structure to partition ecological niches within proposed critical habitat

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