Effects of time–depth recorders on maternal foraging and attendance behavior of Antarctic fur seals (Arctocephalus gazella)

1995 ◽  
Vol 73 (8) ◽  
pp. 1538-1544 ◽  
Author(s):  
Brian G. Walker ◽  
Peter L. Boveng
Keyword(s):  
Statistical Power ◽  
Small Sample ◽  
Arctocephalus Gazella ◽  
Marine Animals ◽  
Nursing Visit ◽  
Fur Seals ◽  
Instrument Type ◽  
Variable Nature ◽  
Radio Transmitters ◽  
Antarctic Fur Seals

We evaluated the difference in average durations of foraging trips and nursing visits to shore between one group of female Antarctic fur seals (Arctocephalus gazella) carrying radio transmitters only and another group carrying time–depth recorders (TDRs) and radio transmitters during their first five postpartum foraging trip – nursing visit cycles. Data were collected from 105 different fur seals in five breeding seasons (1989 – 1990 to 1993 – 1994) on Seal Island, Antarctica. Average foraging-trip and nursing-visit durations were significantly greater for the seals carrying TDRs and radio transmitters than for seals carrying radio transmitters only (two-way ANOVA, year × instrument type; trip, P = 0.004; visit, P = 0.04). Historically, instrument-effect studies on marine animals have focused on smaller species and larger instrument to body size ratios. Because of small sample sizes (the number of instruments successfully deployed and retrieved) and the typically variable nature of data from TDRs, the statistical power to detect significant differences due to instrument effects has been low. The evidence of instrument effects on Antarctic fur seals has possible implications for studies utilizing devices attached to similar-sized animals: results may not be representative of the natural (non-instrumented) population.

scholarly journals Chemical patterns of colony membership and mother-offspring similarity in Antarctic fur seals are reproducible

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10131
Author(s):  
Jonas Tebbe ◽  
Emily Humble ◽  
Martin Adam Stoffel ◽  
Lisa Johanna Tewes ◽  
Caroline Müller ◽  
...  
Keyword(s):  
Statistical Power ◽  
Small Sample ◽  
Chemical Data ◽  
Gas Chromatography Mass Spectrometry ◽  
Original Research ◽  
Replication Studies ◽  
Fur Seals ◽  
Research Findings ◽  
Antarctic Fur Seals ◽  
Exact Replication

Replication studies are essential for evaluating the validity of previous research findings. However, it has proven challenging to reproduce the results of ecological and evolutionary studies, partly because of the complexity and lability of many of the phenomena being investigated, but also due to small sample sizes, low statistical power and publication bias. Additionally, replication is often considered too difficult in field settings where many factors are beyond the investigator’s control and where spatial and temporal dependencies may be strong. We investigated the feasibility of reproducing original research findings in the field of chemical ecology by performing an exact replication of a previous study of Antarctic fur seals (Arctocephalus gazella). In the original study, skin swabs from 41 mother-offspring pairs from two adjacent breeding colonies on Bird Island, South Georgia, were analyzed using gas chromatography-mass spectrometry. Seals from the two colonies differed significantly in their chemical fingerprints, suggesting that colony membership may be chemically encoded, and mothers were also chemically similar to their pups, hinting at the possible involvement of phenotype matching in mother-offspring recognition. In the current study, we generated and analyzed chemical data from a non-overlapping sample of 50 mother-offspring pairs from the same two colonies 5 years later. The original results were corroborated in both hypothesis testing and estimation contexts, with p-values remaining highly significant and effect sizes, standardized between studies by bootstrapping the chemical data over individuals, being of comparable magnitude. However, exact replication studies are only capable of showing whether a given effect can be replicated in a specific setting. We therefore investigated whether chemical signatures are colony-specific in general by expanding the geographic coverage of our study to include pups from a total of six colonies around Bird Island. We detected significant chemical differences in all but a handful of pairwise comparisons between colonies. This finding adds weight to our original conclusion that colony membership is chemically encoded, and suggests that chemical patterns of colony membership not only persist over time but can also be generalized over space. Our study systematically confirms and extends our previous findings, while also implying more broadly that spatial and temporal heterogeneity need not necessarily negate the reproduction and generalization of ecological research findings.

scholarly journals Chemical patterns of colony membership and mother-offspring similarity in Antarctic fur seals are reproducible over time

2020 ◽  
Author(s):  
Jonas Tebbe ◽  
Emily Humble ◽  
Martin A. Stoffel ◽  
Lisa J. Tewes ◽  
Caroline Müller ◽  
...  
Keyword(s):  
Statistical Power ◽  
Small Sample ◽  
Chemical Data ◽  
Gas Chromatography Mass Spectrometry ◽  
Original Research ◽  
Replication Studies ◽  
Fur Seals ◽  
Research Findings ◽  
Over Time ◽  
Antarctic Fur Seals

AbstractReplication studies are essential for assessing the validity of previous research findings and for probing their generality. However, it has proven challenging to reproduce the results of ecological and evolutionary studies, partly because of the complexity and lability of many of the phenomena being investigated, but also due to small sample sizes, low statistical power and publication bias. Additionally, replication is often considered too difficult in field settings where many factors are beyond the investigator’s control and where spatial and temporal dependencies may be strong. We investigated the feasibility of reproducing original research findings in the field of chemical ecology by attempting to replicate a previous study by our team on Antarctic fur seals (Arctocephalus gazella). In the original study, skin swabs from 41 mother-offspring pairs from two adjacent breeding colonies on Bird Island, South Georgia, were analysed using gas chromatography-mass spectrometry. Seals from the two colonies differed significantly in their chemical fingerprints, suggesting that colony membership may be chemically encoded, and mothers were also chemically similar to their pups, implying that phenotype matching may be involved in mother-offspring recognition. Here, we generated and analysed comparable chemical data from a non-overlapping sample of 50 mother-offspring pairs from the same two colonies five years later. The original results were corroborated in both hypothesis testing and estimation contexts, with p-values remaining highly significant and effect sizes, standardized between studies by bootstrapping the chemical data over individuals, being of comparable magnitude. We furthermore expanded the geographic coverage of our study to include pups from a total of six colonies around Bird Island. Significant chemical differences were observed in the majority of pairwise comparisons, indicating not only that patterns of colony membership persist over time, but also that chemical signatures are colony-specific in general. Our study systematically confirms and extends our previous findings, while also implying that temporal and spatial heterogeneity need not necessarily negate the reproduction and generalization of ecological research findings.

Predation on cephalopods by Antarctic fur seals, Arctocephalus gazella , at two localities of the Scotia Arc, Antarctica

Polar Biology ◽  
1999 ◽  
Vol 21 (1) ◽  
pp. 59-63 ◽  
Author(s):  
G. A. Daneri ◽  
U. Piatkowski ◽  
N. R. Coria ◽  
A. R. Carlini
Keyword(s):  
Arctocephalus Gazella ◽  
Fur Seals ◽  
Scotia Arc ◽  
Antarctic Fur Seals
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