Females trade off the uncertainty of breeding resource suitability with male quality during mate choice in an anuran

Choice of nest attributes as a frontline defense against brood parasitism

Breeding- and nest-site choice is a behavioral strategy often used to counter negative interactions. Site choices before breeding prevent costs of predation and competition but have been neglected in the context of brood parasitism. For hosts of brood parasites, the earlier brood parasitism is prevented in the breeding cycle the lower the future costs. Suitable nest-sites for cavity-nesting common redstarts (Phoenicurus phoenicurus), a host of the common cuckoo (Cuculus canorus), are a limited resource, but their cavity-nesting strategy could potentially deter predators and brood parasites. We altered the entrance size of breeding cavities and investigated redstart nest-site choice and its consequences to nest predation and brood parasitism risk, although accounting for potential interspecific competition for nest sites. We set-up paired nest-boxes and let redstarts choose between 7 cm and 5 cm entrance sizes. Additionally, we monitored occupancy rates in nest-boxes with 3 cm, 5 cm, and 7 cm entrance sizes and recorded brood parasitism and predation events. We found that redstarts preferred to breed in 5 cm entrance size cavities, where brood parasitism was eliminated but nest predation rates were comparable to 7 cm entrance size cavities. Only in 3 cm cavities both, brood parasitism and predation rates were reduced. In contrast to the other cavity-nesting species, redstart settlement was lowest in 3 cm entrance size cavities, potentially suggesting interspecific competition for small entrance size cavities. Nest-site choice based on entrance size could be a frontline defense strategy that redstarts use to reduce brood parasitism.

Reproductive ecology and territorial behavior of Boana goiana (Anura: Hylidae), a gladiator frog from the Brazilian Cerrado

Anuran males and females adopt different reproductive and behavioral strategies in different contexts. We investigated the reproductive ecology and territorial behavior of the treefrog Boana goiana (B. Lutz, 1968) from the Brazilian Cerrado. We hypothesized that competitor density/proximity would increase the behavioral responses of B. goiana males, and that mating would be assortative. We also tested if the number of eggs correlates with female size and if there is a trade-off between clutch size and egg size. We conducted two territoriality experiments to test the effects of male size, competitor proximity and competitor density. Larger males called more in the presence of a second male. In the second experiment, the largest males emitted more calls and the distance to the nearest male increased as resident males called more. In both experiments, the number of calls was influenced by either male size or spacing between males. Some males behaved as satellites, probably to avoid fights. Our analyses indicate that females choose males with similar sizes to their own, corroborating our hypothesis of size-assortative mating. We found no relationships between female size and clutch size/volume, and between egg size and number of eggs per clutch. We also report multiple spawning for this species. The low incidence of physical combats and the spacing pattern indicate that this species relies almost solely on calls to resolve contests, which could be explained by low motivation, or simply because males avoid combats to decrease injury risks. Thus, acoustic or even multimodal communication seems crucial for social interactions of B. goiana.

Flexible habitat choice by aphids exposed to multiple cues reflecting present and future benefits

Mothers choose suitable habitats for laying offspring to maximize fitness. Because habitat quality varies in space and time, mothers gather information to choose among available habitats through multiple cues reflecting different aspects of habitat quality at present and in the future. However, it is unclear how females assess and integrate different cues associated with current rewards and future safety to optimize oviposition/larviposition decisions, especially across small spatial scales. Here, we tested the individual and interactive effects of leaf surface, leaf orientation, and leaf bending direction on larviposition site choice and fitness benefits of wheat aphids (Metopolophium dirhodum) within individual leaves. We found that females preferred upper over lower surfaces for gaining current food-related rewards, downward- over upward-facing surfaces for avoiding potential abiotic risks, and sunken over protruding surfaces for avoiding potential biotic risks. When facing conflicting cues during larviposition, females preferred downward-facing/sunken surfaces over upper surfaces, suggesting that females prioritize potential safety at the cost of current rewards during decision making. Most importantly, our combined-cue experiments showed females still assessed secondary cues (i.e., the upper surface) when first-ranked cues (i.e., the downward-facing/sunken surface) are available, even though females only gained relatively small fitness rewards through secondary cues, and females can integrate different cues associated with current rewards and potential safety in a multiplicative way to make flexible and complex larviposition decisions. Overall, our findings provide new insights into how animals collect and process multi-cue information associated with current rewards and potential safety to maximize fitness at small spatial scales.