Predator dietary studies often assume that diet is reflective of the diversity and relative abundance of their prey. This interpretation ignores species-specific behavioural adaptations in prey that could influence prey capture. Here, we develop and describe a scalable biologging protocol, using animal-borne camera loggers, to elucidate the factors influencing prey capture by a seabird, the gentoo penguin (Pygoscelis papua). From the video evidence, we show, for the first time, that aggressive behavioural defence mechanisms by prey can deter prey capture by a seabird. Furthermore, we provide evidence demonstrating that these birds, which were observed hunting solitarily, target prey when they are most discernible. Specifically, birds targeted prey primarily while ascending and when prey were not tightly clustered. In conclusion, we show that prey behaviour can significantly influence trophic coupling in marine systems because despite prey being present, it is not always targeted. Thus, these predator-prey relationships should be accounted for in studies using marine top predators as samplers of mid to lower trophic level species.
Movie S1: General footage overview for gentoo penguins
General overview of footage obtained from animal-borne camera loggers attached to Gentoo penguins at the Falkland Islands. Examples include: Feeding on lobster krill, feeding on large fish, a full dive where the bird feeds on small fish then pursues and captures a squid, a full dive where lobster krill on the seafloor is ignored and unidentified prey items are shown, lobster krill on seafloor being predated upon, and foraging for small fish.
Handley_movieS1_LowRes.mp4
Movie S2: Lobster krill defends against predation
Examples of lobster krill actively avoiding predation by gentoo penguins, by defending themselves with their pincers.
Handley_movieS2_LowRes.mp4
Movie S3: Swarms of lobster krill
Examples of gentoo penguins not feeding and feeding off of large swarms of lobster krill.
Handley_s3_Swarms_LowRes.wmv
Movie S4: Intra and interspecific interactions
Examples of intra and interspecific interactions for gentoo penguins at the Falkland Islands.
Handley_s4_Interactions_LowRes.wmv
HandleyJM_2017_PenguinPrey_SuppData_RSOS
File: “HandleyJM_GNP_CAM_Analysis.R”
• A synthesis of R code used to generate the results presented in the paper
File: “GNP_FLK_CAM_PreyDetail.Rdata”
• R data file of the annotated camera data used for analyses in the paper
File: “P1_AnimalCam_SuppCode_Merge Trips.R” & “P2_AnimalCam_SuppCode_Feeding events.R”
• R scripts which require the other supplementary files:
- SpeciesX_Location_2013_DepID21_1of3_Vid.csv
- SpeciesX_Location_2013_DepID21_2of3_Vid.csv
- SpeciesX_Location_2013_DepID21_3of3_Vid.csv
- SpeciesX_Location_2013_DepID24_1of3_Vid.csv
- SpeciesX_Location_2013_DepID24_2of3_Vid.csv
- SpeciesX_Location_2013_DepID24_3of3_Vid.csv
File: “P3_AnimalCam_SuppCode_MergeCAMtoTDRandGPS.R”
• R script which gives example of how data from multiple devices can be merged, and requires the supplementary R files:
- BR14_GNP_FLK_2013_CAM_SuppData.R
- BR14_TDR_2013.14_GentooFI_ZOCdives.csv
- BR14_2013-14_GentooFI_bf_track.csv