acta ethologica最新文献

Long-finned pilot whales and killer whales are widely distributed across the North Atlantic, but few studies have reported their occurrence in Icelandic coastal waters. Here, we use sightings data from research platforms and whale watching tours in six regions of Iceland from 2007 to 2020 to show that the occurrence of long-finned pilot and killer whales varied with region and season. Killer whales were regularly encountered in the south of Iceland during summer and west of Iceland during winter/spring. Long-finned pilot whales were only seen during the summer and were most often encountered in the south, west, and northwest of Iceland. Long-finned pilot whale occurrence in the south of Iceland appeared to increase during the study period but killer whale occurrence showed no noticeable changes. Long-finned pilot whales were sighted often in the areas that were also frequented by killer whales and interspecific interactions were commonly observed when both species co-occurred. Interactions appeared to be antagonistic, with killer whales often avoiding long-finned pilot whales and sometimes fleeing at high speed, similar to what has been described elsewhere in the North Atlantic. In the majority of interactions observed (68%), killer whales avoided long-finned pilot whales by moving away, but in 28% avoidance was at high speed with both species porpoising. This variability in the type of behavioural responses indicates that interactions may be more complex than previously described. We discuss regional trends in long-finned pilot whale and killer whale sightings and potential drivers of the observed interactions.

The activity of small invasive mammals, the American mink (Neovison vison) and the coypu (Myocastor coypus), was monitored in western part of Slovakia. Camera traps were located at 9 localities where these animals occur and were monitored throughout all four seasons. The activity of these two invasive species was analysed with regard to the habitat type and environment and, but especially, to the relationship to season, daily period, part of the day and activities. The following animal activities were observed: environmetal exploration, movement, swimming, stationary, grooming, play, flee, feeding, change of environment, mating behaviour and territorial marking. In case of the coypu, crepuscular and nocturnal activities were prevalent. Activity during daytime occurred mostly during winter days with low temperatures. On the other hand, American minks were mostly diurnal. The shift in behaviour compared to American minks in their native environment could be a sign of its adaptation to a new environment. Our research also showed seasonal changes in activity of both invasive mammals. This research could serve as a basis for management schemes to combat the presence and dispersal of these two invasive mammal species.

The Brazilian ruby, Heliodoxa rubricauda, is a forest species of hummingbird endemic to the Atlantic Forest. It belongs to an Andean clade of birds with robust and strong legs and adapted to feed on inflorescences of plants from high regions and influenced by strong winds. It occurs from northeastern to southern Brazil on slopes, sierras, and mountains and has the little-known behavior of bathing in waterfalls and forest streams. Based on five field observations made in the state of São Paulo, and records available from online photo platforms, we concluded that H. rubricauda is the only species of hummingbird in Brazil that bathes by settling on rocks of forest waterfalls with medium to strong currents. This behavior is made possible by the robust and strong legs the species inherited from its evolutionary lineage, which, in the Atlantic Forest, are used for feeding, defense, and bathing. We hypothesize that this behavior is more efficient for body hygiene than other existing behaviors because it allows a greater amount of water to pass over the body, thereby eliminating traces of food and parasites, in addition to reducing risks of predation.

Crab-eating mongooses (Herpestes urva) are widely distributed across Southeast Asia. In Taiwan, the mongoose (H. urva formosanus, endemic subspecies) is a protected species under the Wildlife Protection Act. Crab-eating mongooses have been observed near streams, riversides, agricultural lands, and shallow mountain areas. Additionally, as described in this short communication, by using a remote camera, we observed a small population of mongooses in the coastal forest in Kenting National Park in Taiwan. The mongooses in the coastal forest were observed eating land hermit crabs, which is the first-ever recorded observation of this behavior. Mongooses are known to consume crabs (Brachyura), insects, and some small reptiles. However, this article presents the first record case of mongooses using stone anvil to crack open land hermit crabs. From our observations and field records, we determined that mongooses use flat rocks as anvils and their front paws to tap hermit crabs’ shells repeatedly to break the shells and remove the hermit crabs. We also observed that the mongooses only ate the abdomens of large hermit crabs. Additional studies are necessary to determine why the mongooses migrated to the coastal forest and how they learned to open hermit crab shells. This behavior of mongooses might help them move into living in coastal forests.

Predation strategies are often habitat-dependent; therefore, contrasting biomes, such as rainforests and seasonally dry forests, may be useful for understanding how the environment influences predatory behavior. The aim of this study was to evaluate the prey capture behavior of scorpions from contrasting habitats in northeastern Brazil. The scorpions’ use of the stinger and movement probability after prey capture were analyzed. We collected 120 scorpions, 60 from the Atlantic Forest and 60 from the Caatinga drylands. Our results indicate that scorpions from the Atlantic Forest tended to use their stinger more frequently than those from the Caatinga habitat. We also found that Caatinga scorpions moved approximately 40% more after prey capture than the Atlantic Forest species. Environmental pressures related to the metabolic costs of venom production and potential predation risk may partially explain the differential behavior observed in this study. Therefore, our results suggest that despite the morphological differences between species, animals from contrasting habitats may show different prey capture strategies.

Heterospecifics eavesdrop on mobbing calls and respond with appropriate behavior, but the functional aspects are less studied. Here, I studied whether jays (Garrulus glandarius) eavesdrop on blackbird (Turdus merula) mobbing calls in comparison to blackbird song. Furthermore, it was studied whether jays provided with extra information about predators differ in their response. Three different experimental designs were carried out: (1) control playback of blackbird song to control for the species’ presence, (2) experimental playback of different mobbing events of blackbirds towards different predators, (3) experimental playback similar to (2) but combined with different predator models. In the combined experiments, mobbing calls were tied to the respective visual stimuli. Comparing the experiments with and without predator presentation, a similar number of jays occurred during the playback-only experiment (n = 7) and the playback combined with model presentation (n = 6). However, during the playback-only experiment, jays approached the speaker closer and stayed for longer time in the nearer surrounding. These results show that jays need extra information to make an informed decision.

Ecological factors may affect resource availability and distribution, impacting foraging and burrow construction behaviours. Clyomys laticeps is a caviomorph rodent with subterranean habits occurring on the Brazilian Cerrado domain (savanna-like) until the Paraguayan Chaco. We investigated their underground system’s architecture taking into account the vegetation and climate. We hypothesised that the sparse food distribution in the winter would promote longer tunnels and more complex architectures to connect more distant foraging areas, supposing that the species moved underground to avoid predators; moreover, the winter would promote food storage. We excavated eleven Clyomys underground systems and measured their size and internal parameters (tunnel and chamber width, length and depth) and complexity (linearity and convolution). We noticed that half of the systems were in the open landscape (OL) and half on vegetation covered (VL). If the anti-predation theory was right, we would find shorter tunnels on the VL systems. We found systems from 2 to 24 m² and up to 22 m long. The deeper and biomass scarcer tunnels were on VL during the dry season, supposedly when animals would need underground water but not stocked food (the palm season). Also, they were more complex (higher circularity and convolution indexes) in OL, favouring our anti-predation hypothesis. Furthermore, Clyomys burrows offer refuge for other species such as arthropods, snakes, amphibians, and birds. We conclude that systems’ architecture is related to vegetation presence and seasonal foraging challenges. This rodent may construct its systems for shelter, food storage and as a safe trail among foraging areas.

Wolf packs perform group vocalizations called chorus howls. These acoustic signals have a complex structure and could be involved in functions such as strengthening of social bonds, territory advertisement, or spacing between packs. We analyzed video recordings of 46 chorus howls emitted by 10 packs of wolves held in captivity, in order to investigate whether sex, age, social status, pack, or individual influence the way wolves participate in a chorus. We found that, during a chorus, wolves vocalized 63% of the time, with the howl being the most common vocalization (36% of the chorus duration), followed by woa (13.5%), other vocalizations (11.8%), and bark (1.7%). The main factor affecting the vocal behavior of wolves was age, since young wolves vocalized less and uttered shorter acoustic signals than adults. The discriminant analysis carried out with the wolves of Cañada Real pack assigned 89.3% of the cases to the correct individual, which is much better than the assignment expected by chance, suggesting that individuals could have a unique vocal usage during a chorus howl, mainly due to the use of howls and woa-woa howls. Based on our results, we propose that in the context of a chorus the woa-woa howl is important, although further research is needed to address this issue properly.