Leaf bathing in ring-necked parakeets Psittacula krameri

Bathing is one of the main actions birds perform as part of their preening. They may bathe in water, snow, dust, and even ants. Leaf bathing, where birds make use of water droplets on leaves to bathe, is less common. Here we describe four observations between 2017 and 2021 of ring-necked parakeets Psittacula krameri bathing on water droplets on leaves during rain.Over the past twenty years we have often seen monk parakeets Myiopsitta monachus bathing in puddles but never on leaves. The monk parakeet often forages on the ground, but ring-necked parakeets are reluctant to do so. We therefore interpret that the leaf bathing we observed in the ring-necked parakeet could be an anti-predatory strategy to avoid going down to the ground.

Acoustically eavesdropping predators take longer to capture prey signalling in aggregation

Prey signalling in aggregation become more conspicuous with increasing numbers and tend to attract more predators. Such grouping may, however, benefit prey by lowering the risk of being captured due to the predator's difficulty in targeting individuals. Previous studies have investigated anti-predatory benefits of prey aggregation using visual predators, but it is unclear whether such benefits are gained in an auditory context. We investigated whether katydids of the genus Mecopoda gain protection from their acoustically eavesdropping bat predator, Megaderma spasma, when calling in aggregation. In a choice experiment, bats approached calls of prey aggregations more often than those of prey calling alone, indicating that prey calling in aggregation are at higher risk. In prey capture tasks, however, the average time taken, and the number of flight passes made by bats before capturing a katydid, were significantly higher for prey calling in aggregation as compared to calling alone, indicating that prey face lower predation risk when calling in aggregation. Another common anti-predatory strategy, calling from within vegetation, increased the time taken by bats to capture katydids calling alone but did not increase the time taken to capture prey calling from aggregations. The increased time taken to capture a prey calling in aggregation compared to solitary calling prey offers an escape opportunity, thus providing prey signalling acoustically in aggregations with anti-predatory benefits. For bats, greater detectability of calling prey aggregations is offset by lower foraging efficiency, and this trade-off may shape predator foraging strategies in natural environments.

Diet Diversity in Carnivorous Terebrid Snails Is Tied to the Presence and Absence of a Venom Gland

Predator-prey interactions are thought to play a driving role in animal evolution, especially for groups that have developed venom as their predatory strategy. However, how the diet of venomous animals influences the composition of venom arsenals remains uncertain. Two prevailing hypotheses to explain the relationship between diet and venom composition focus on prey preference and the types of compounds in venom, and a positive correlation between dietary breadth and the number of compounds in venom. Here, we examined venom complexity, phylogenetic relationship, collection depth, and biogeography of the Terebridae (auger snails) to determine if repeated innovations in terebrid foregut anatomy and venom composition correspond to diet variation. We performed the first molecular study of the diet of terebrid marine snails by metabarcoding the gut content of 71 terebrid specimens from 17 species. Our results suggest that the presence or absence of a venom gland is strongly correlated with dietary breadth. Specifically, terebrid species without a venom gland displayed greater diversity in their diet. Additionally, we propose a revision of the definition of venom complexity in conoidean snails to more accurately capture the breadth of ecological influences. These findings suggest that prey diet is an important factor in terebrid venom evolution and diversification and further investigations of other understudied organisms, like terebrids, are needed to develop robust hypotheses in this area.

PREDATION OF PALE-BREASTED THRUSH EGGS BY THE ARIEL TOUCAN IN BRAZIL: FAILURE OF THE ANTI-PREDATORY STRATEGY

The Channel-billed Toucan (Ramphastos vitellinus ariel) is an omnivorous bird that eventually is nest-robbers. Several birdsongs display anti-predatory strategies such as attacks and mobbing calls to face this kind of predators. This note reports a predatory event of one Channel-billed Toucan upon eggs of Pale-breasted Thrush (Turdus leucomelas), and describe the anti-predatory behavior, principally alert and mobbing calls of the thrush. Even though the Pale-breasted Thrush displayed the anti-predatory behaviors to harass the toucan, the egg predation was not avoided. Although the predation upon eggs by Ramphastos vitellinus has been reported several times, the majority of reports lacks of identity of the bird species affected, this being the first confirmed record in Turdus leucomelas.

Amazon: A story of accumulation through intellectual rentiership and predation

This article elaborates on intellectual monopoly theory as a form of predation and rentiership using Amazon as a case study. By analysing Amazon’s financial statements, scientific publications and patents, we show that Amazon’s economic power heavily relies on its systematic innovations and capacity to centralize and analyse customized data that orients its business and innovations. We demonstrate how Amazon’s innovation activities have evolved over time with growing importance of technologies related to data and machine learning. We also map Amazon’s innovation networks with academic institutions and companies. We show how Amazon appropriates intellectual rents from these networks and from technological cooperation with other intellectual monopolies. We argue that Amazon, as other data-driven monopolies, predates value from suppliers and third-party companies participating in its platform. One striking characteristic of Amazon is the low rate of reported profits. The centrality of innovations leads us to suggest an alternative calculation that shows that Amazon’s profits are not as low as they appear in Annual Reports. We also argue that lower profits are coherent with Amazon’s rentiership and predatory strategy since they contribute to the avoidance of accusations of excessive market power. Finally, the paper offers preliminary observations on: (i) the complementarities between financial and intellectual rentierism and (ii) how data-driven intellectual monopoly expands big corporations’ political power. Going beyond the specific case of Amazon, we thus contribute to a better understanding of the role of lead firms and power dynamics within innovation networks.

Construction of the nest of Amazilia rutila De Lattre (Trochillidae) and its anti- predatory defensive strategy in a medium deciduous forest in Campeche, Mexico

The Yucatan peninsula (YP) is part of a biogeographical area characterised by its diversity of flora and fauna, among which are the birds, mainly hummingbirds, which are indicators of the state of conservation of the ecosystems. In birds, the site establishment and construction of nest plays a fundamental role for reproduction and survival rate, the selection of materials occurs opportunistically, but birds tend to use fresh leaves of plants with antimicrobial properties or that allow the depletion of ectoparasites in their nests. In this sense, for the first time we recorded for the cinnamon hummingbird (Amazilia rutila De Lattre), the materials used for the construction of its nest and the site of establishment of the nest in the host plants in two sites of a medium sub-deciduous forest in, Mexico. We recorded the construction of nests of A. rutila in two locations in Campeche; in the first site the nest was found in a chaya bush Cnidoscolus aconitifolius (Mill.) I.M. Johnst. (Euphorbiaceae); most possibly as an anti-predatory strategy for trichomes in the form of sharp hairs and spines that the plants possess in their stems and leaves. In the second site, the nest was found in a mango tree Mangifera indica L. (Anacardiaceae). The main vegetative material identified for the construction of the nests in both locations, were made from pappus (thin and cottony filament that possess the seeds for the dispersion) from Asclepias curassavica L. (Apocynaceae).

Deflecting the point of attack

Deflection involves prey influencing the position of the initial contact of a predator with the prey’s body, in a way that benefits the prey. These traits might be behavioural, involve morphological structures, or pigmentation and other appearance traits, or combinations thereof. The benefit to the prey is normally considered to be an increased likelihood of escaping the attack, and so the benefit to the prey comes at a cost to the predator. The anti-predatory mechanisms covered in this book vary greatly in current understanding of their taxonomic distribution, and deflection is an extreme example of this. It has been postulated to occur in a sparse and eclectic group of organisms, and the evidence for its existence is quite variable among members of this group. We spend the bulk of this chapter exploring this evidence. We argue that the evidence currently available allows some speculation on the evolutionary ecology of this anti-predatory strategy, and we develop hypotheses that aim to broaden the scope of research into deflective traits.

Predation among microorganisms: A huge potential of interspecies dependencies

There are many interactions between species (including bacteria) in the environment. One of them is predation, which always leads to the death of a prey. Described in this review Bdellovibrio bacteriovorus (Deltaproteobacteria) and Micavibrio aeruginosavorus (Alfaproteobacteria) are uniflagellate, rod shaped and curved obligate predators of Gram-negative bacteria. Both species belong to the group of BALOs (Bdellovibrio and like organisms). B. bacteriovorus use periplasmic predatory strategy and M. aeruginosavorus are epibiotic hunters. BALOs have found application in both medicine in combating microorganisms responsible for food poisoning and outside of medicine (agriculture and food) as plant protection products and as measures used to prevent the spoiling of food. As a result of searching for effective therapies in the treatment of infections caused by drug-resistant strains of bacteria, it has been shown that predators feed on pathogenic bacteria without showing immunogenicity to humans. Predatory bacteria are able to destroy the multi – and single-species biofilms. Recent studies have indicated the possibility of B. bacteriovorus to destroy the biofilm formed by Staphylococcus aureus. It is postulated that a double predatory strategy of B. bacteriovorus and harmless BALOs towards mammalian cells could be used to treat infections in vivo, particularly in those cases when standard therapy fails.