Predation of archival tagged Dolly Varden, Salvelinus malma, reveals predator avoidance behaviour and tracks feeding events by presumed beluga whale, Delphinapterus leucas, in the Beaufort Sea

Background We report compelling evidence suggesting a predation event of a pop-up satellite archival tagged anadromous Dolly Varden (Salvelinus malma) by a marine mammal during summer in the Beaufort Sea based on abrupt changes in temperature and vertical movements. This observation provides insight on predator avoidance behaviour by Dolly Varden and the predator’s feeding frequency while the tag was ingested. Based on published distribution and ecology information, we presumed the predator was a beluga whale (Delphinapterus leucas). Supplemental satellite telemetry data from previously tagged Dolly Varden and beluga whales were used to determine the extent of spatial and vertical overlap between species in the area where predation occurred. Results Prior to the predation event, depths and temperatures occupied by the tagged Dolly Varden averaged 1.1 m and 3.1 °C, respectively. On July 7, 2020, depths remained shallow apart from a sudden dive to 12.5 m (16:45 UTC) followed by a precipitous increase in temperature from 4.4 to 27.1 °C (16:52 UTC) suggesting predation by an endotherm. Subsequent readings indicated the endotherm had a resting stomach temperature of 36.1 °C. Including the predation event, eight separate feeding events were inferred during the 20-h period the tag was ingested (before presumed regurgitation) based on subsequent declines in stomach temperatures (mean decline to 31.1 °C) that took an average of 24.1 min to return to resting temperature. The predator occupied mainly shallow depths (mean = 2.3 m), overlapping with tagged belugas that spent 76.9% of their time occupying waters ≤ 2.5 m when frequenting the area occupied by tagged Dolly Varden in the Canadian Beaufort Sea in July. Back-calculation based on tag drift and mean displacement by tagged belugas indicated the predation likely occurred west of the Mackenzie Delta. Conclusion Our findings provide new information on both anti-predator behaviour by, and marine predators of, Dolly Varden in the Beaufort Sea. We provide the first estimate of feeding frequency and stomach temperature recovery in a presumed wild beluga, and evidence for shallow foraging behaviour by belugas. Elucidating the likely predator and exploring the extent of overlap between Dolly Varden and beluga whales contributes towards knowledge on the trophic interactions in the Beaufort Sea.

Leptodactylus vastus (LEPTODACTYLIDAE) predation on an endemic frog, and a compilation of its diet

Diet composition constitutes basic information on the natural history of the species. Despite the amount of data acquired in the last years, much remains to be known specially for geographically widespread species. Here we compiled the available dietary items of Leptodactylus vastus and report the first predation event upon Rupirana cardosoi by a juvenile L. vastus. The fact these species are syntopic in the region probably resulted in this novel predation event. Different from previous L. vastus predation observations, the specimens we observed do not present a striking difference in body size, but L. vastus was able to almost swallow L. cardosoi, coherent with findings that mouth size is related to prey selection in anurans. Also, our literature review showed that L. vastus is a generalist and opportunistic predator, that prey upon small vertebrates (Amphibia, Squamata, and Mammalia).

PREDATION ON A BRAZILIAN PYGMY GECKO, Chatogekko amazonicus (SQUAMATA, SPHAERODACTYLIDAE), BY A WOLF-SPIDER, Lycosa sp. (ARANEAE, LYCOSIDAE)

A predation event on Chatogekko amazonicus (Sphaerodactylidae) by the wolf-spider Lycosa sp. (Lycosidae) was observed in an Amazon forest, in north Brazil.

PREDATORY INTERACTION BETWEEN TWO ANURAN SPECIES WITH Thamnodynastes chaquensis (COLUBRIDAE) IN THE BRAZILIAN CERRADO

Although predatory events are uncommon to be recorded in nature, these data are important tools for understanding prey-predator interaction of the involved species. Snakes of genus Thamnodynastes are known for having an anuran diet, including some species of hylid frogs in their diet. Despite this, this pattern does not include T. chaquensis since there are no records on predation or trophic interaction with hylid frogs.Here, we report the first predatory interaction between T. chaquensis and two hylid frogs in Brazilian Cerrado. The first predation event with treefrog Boana caiapo occurred with success but, the second with B. albopunctatadid not. Connecting trophic links within an ecosystem requires in-depth knowledge of its species and their intraspecific interactions. In this context, records of the predation and predation attempts such as these may help to connect unknown trophic links, which helps to understand aspects of the natural history of the species involved.

Observations on co-existing late-instar caterpillars of the Orange-tip butterfly, Anthocharis cardamines (Linnaeus) (Lepidoptera: Pieridae)

Co-existence between late instar larvae of Anthocharis cardamines on multiple occupied Lunaria annua plants was monitored in a suburban Edinburgh garden and a stand-off between final instar larvae on Sisymbrium officinale in countryside near Leipzig was recorded photographically. Occupation of mauve-flowered Lunaria plants was significantly higher than white-flowered ones. The notion that the resting behaviour of final instar larva along the top of seed pods camouflages them is challenged. Although not part of that argument, a major predation event by Vespula vulgaris was seen on Lunaria.

The importance of fieldwork over predictive modeling in quantifying predation events of carnivores marked with GPS technology

© 2017 American Society of Mammalogists. Global positioning system (GPS) technology has revolutionized the study of carnivores. Researchers commonly estimate kill rates with GPS data using the following steps. Firstly, researchers mark individual animals and fit them with GPS collars. Next, they visit a subset of "GPS clusters" (aggregated location data) during field surveys and assign spatiotemporal covariates associated with predation and non-predation events. Lastly, they develop predictive models with data collected in the field to estimate the probability that each cluster they did not visit in the field was a predation event. Such predation models help reduce field efforts and save money; however, these models are prone to error when carnivores eat prey of different sizes or exhibit shorter-than-expected handling times. We simulated reduced field efforts to investigate the reliability of predictive modeling in determining diet composition and detecting predation events for 3 puma (Puma concolor) populations with different prey assemblages and potential effects on handling time of carcasses. We visited a total 1,896 clusters in Chilean Patagonia, Colorado, and California, of which 1,752 clusters (∼92%) were included to build and test predation models. Across all study areas, the total time a puma spent at a cluster was the only reliable predictor of a cluster being a predation event. When we reduced field efforts by selectively removing GPS clusters < 12 and < 24 h in length, model performance improved but produced inaccurate results. Predation models underestimated the number of predation events in California and Colorado and significantly over-or underestimated the number of predation events in Patagonia. Selectively reducing field efforts also reduced the diversity and evenness of prey we recorded in puma diets. Randomly reducing field efforts, in contrast, reduced the precision of model estimates. Our results highlight the importance of conducting intensive fieldwork over predation modeling to measure prey selection and kill rates of carnivores.

The importance of fieldwork over predictive modeling in quantifying predation events of carnivores marked with GPS technology

© 2017 American Society of Mammalogists. Global positioning system (GPS) technology has revolutionized the study of carnivores. Researchers commonly estimate kill rates with GPS data using the following steps. Firstly, researchers mark individual animals and fit them with GPS collars. Next, they visit a subset of "GPS clusters" (aggregated location data) during field surveys and assign spatiotemporal covariates associated with predation and non-predation events. Lastly, they develop predictive models with data collected in the field to estimate the probability that each cluster they did not visit in the field was a predation event. Such predation models help reduce field efforts and save money; however, these models are prone to error when carnivores eat prey of different sizes or exhibit shorter-than-expected handling times. We simulated reduced field efforts to investigate the reliability of predictive modeling in determining diet composition and detecting predation events for 3 puma (Puma concolor) populations with different prey assemblages and potential effects on handling time of carcasses. We visited a total 1,896 clusters in Chilean Patagonia, Colorado, and California, of which 1,752 clusters (∼92%) were included to build and test predation models. Across all study areas, the total time a puma spent at a cluster was the only reliable predictor of a cluster being a predation event. When we reduced field efforts by selectively removing GPS clusters < 12 and < 24 h in length, model performance improved but produced inaccurate results. Predation models underestimated the number of predation events in California and Colorado and significantly over-or underestimated the number of predation events in Patagonia. Selectively reducing field efforts also reduced the diversity and evenness of prey we recorded in puma diets. Randomly reducing field efforts, in contrast, reduced the precision of model estimates. Our results highlight the importance of conducting intensive fieldwork over predation modeling to measure prey selection and kill rates of carnivores.

Notes on the predation of an assassin bug by a spider in a Neotropical cave

Intraguild predation have rarely been documented in scientific literature, even though this type of interaction can affect population dynamics and competition. In this study we present an intraguild predation event that occurred at different times, but in the same cave, where we observed spiders of the species Enoploctenus cyclotorax preying on specimens of assassin bug Zelurus diasi. Inside the studied caves, food resources are scarce and populations can be fairly small in size. It is possible, therefore, that these events are the result of ecological pressures imposed by the hypogean environment.

Evidence of a predation event on a tagged Mediterranean spearfish (Tetrapturus belone; Pisces, Istiophoridae), inferred from pop-up satellite tagging data

The Strait of Messina is located at the centre of the Mediterranean Sea and is considered a biodiversity hotspot and an obligatory seasonal passage for different pelagic species such as sharks, marine mammals, and billfishes. For the first time, in the Strait of Messina, our research group tagged a Mediterranean spearfish (Tetrapturus belone) using a pop-up satellite archival tag (PSAT). The observation of abiotic parameters (depth, light, and temperature) recorded by the PSAT confirmed that the tagged specimen was predated after about nine hours. The tag was then regurgitated 14 days after the tag deployment date. The analysis of collected data seems to indicate that the predator may be an ectothermic shark, most likely the bluntnose sixgill shark (Hexanchus griseus).