In BriefUsing miniature tags, Egert-Berg et al. record bats' movement and social interactions. Whereas species foraging on ephemeral resources search in groups, switching foraging sites, species foraging on predictable resources search alone, returning to the same sites. The results suggest a connection between resource predictability and group foraging. SUMMARYObservations of animals feeding in aggregations are often interpreted as events of social foraging, but it can be difficult to determine whether the animals arrived at the foraging sites after collective search [1][2][3][4] or whether they found the sites by following a leader [5, 6] or even independently, aggregating as an artifact of food availability [7, 8]. Distinguishing between these explanations is important, because functionally, they might have very different consequences. In the first case, the animals could benefit from the presence of conspecifics, whereas in the second and third, they often suffer from increased competition [3,[9][10][11][12][13]. Using novel miniature sensors, we recorded GPS tracks and audio of five species of bats, monitoring their movement and interactions with conspecifics, which could be inferred from the audio recordings. We examined the hypothesis that food distribution plays a key role in determining social foraging patterns [14][15][16]. Specifically, this hypothesis predicts that searching for an ephemeral resource (whose distribution in time or space is hard to predict) is more likely to favor social foraging [10,[13][14][15] than searching for a predictable resource. The movement and social interactions differed between bats foraging on ephemeral versus predictable resources. Ephemeral species changed foraging sites and showed large temporal variation nightly. They aggregated with conspecifics as was supported by playback experiments and computer simulations. In contrast, predictable species were never observed near conspecifics and showed high spatial fidelity to the same foraging sites over multiple nights. Our results suggest that resource (un)predictability influences the costs and benefits of social foraging. RESULTS AND DISCUSSIONWe compared the movement and social foraging behavior of five bat species (representing four families), which cover a wide range of foraging styles and exploit different resources (see Table 1). Two species rely on ephemeral resources (henceforth the ''ephemeral foragers''): (1) the greater mouse-tailed bat (Rhinopoma microphyllum, Rhinopomatidae), an open-space insectivorous bat that preys on ephemeral insect swarms [17], and (2) the Mexican fish-eating bat (Myotis vivesi, Vespertilionidae), which forages primarily over marine waters [18, 19], where it feeds on local upwellings of fish and crustaceans [18, 19] whose exact location is difficult to predict on any given night. Indeed, our analysis of the spatial distribution of marine chlorophyll (a proxy of marine food availability [20, 21]) indicates low predictability of food spatial distribution over consecutive nights ( Figure...

Inflammation and activation of the acute phase response (APR) are energetically demanding processes that protect against pathogens. Phytohaemagglutinin (PHA) and lipopolysaccharide (LPS) are antigens commonly used to stimulate inflammation and the APR, respectively. We tested the hypothesis that the APR after an LPS challenge was energetically more costly than the inflammatory response after a PHA challenge in the fish-eating Myotis bat (Myotis vivesi). We measured resting metabolic rate (RMR) after bats were administered PHA and LPS. We also measured skin temperature (Tskin) after the LPS challenge and skin swelling after the PHA challenge. Injection of PHA elicited swelling that lasted for several days but changes in RMR and body mass were not significant. LPS injection produced a significant increase in Tskin and in RMR, and significant body mass loss. RMR after LPS injection increased by 140–185% and the total cost of the response was 6.50 kJ. Inflammation was an energetically low-cost process but the APR entailed a significant energetic investment. Examination of APR in other bats suggests that the way in which bats deal with infections might not be uniform.

Although long‐standing theory suggests that biotic variables are only relevant at local scales for explaining the patterns of species' distributions, recent studies have demonstrated improvements to species distribution models (SDMs) by incorporating predictor variables informed by biotic interactions. However, some key methodological questions remain, such as which kinds of interactions are permitted to include in these models, how to incorporate the effects of multiple interacting species, and how to account for interactions that may have a temporal dependence. We addressed these questions in an effort to model the distribution of the monarch butterfly Danaus plexippus during its fall migration (September–November) through Mexico, a region with new monitoring data and uncertain range limits even for this well‐studied insect. We estimated species richness of selected nectar plants (Asclepias spp.) and roosting trees (various highland species) for use as biotic variables in our models. To account for flowering phenology, we additionally estimated nectar plant richness of flowering species per month. We evaluated three types of models: climatic variables only (abiotic), plant richness estimates only (biotic) and combined (abiotic and biotic). We selected models with AICc and additionally determined if they performed better than random on spatially withheld data. We found that the combined models accounting for phenology performed best for all three months, and better than random for discriminatory ability but not omission rate. These combined models also produced the most ecologically realistic spatial patterns, but the modeled response for nectar plant richness matched ecological predictions for November only. These results represent the first model‐based monarch distributional estimates for the Mexican migration route and should provide foundations for future conservation work. More generally, the study demonstrates the potential benefits of using SDM‐derived richness estimates and phenological information for biotic factors affecting species distributions.

Resumen. Los mamíferos son uno de los grupos más conspicuos de las comunidades terrestres de vertebrados y muestran una serie de características internas y externas que los han llevado a ser exitosos en casi todos los ecosistemas del mundo. El objetivo de esta revisión es actualizar el estado de conocimiento de los mamíferos de México. En México los mamíferos forman un grupo altamente diverso, ubicando al país en el tercer lugar mundial con 564 especies silvestres, alcanzando aproximadamente el 10% de la diversidad total. La descripción de las especies no ha sido homogénea a lo largo del tiempo y tuvo un mayor auge desde mediados de 1700 hasta 1950. La distribución de los mamíferos incluye todo el territorio nacional; el 77% son especies menores a 5 kg y pertenecen, principalmente, a los órdenes Rodentia, Chiroptera y Soricomorpha. Las tendencias poblacionales están poco documentadas en la mayoría de los órdenes pero, en general, los mamíferos han visto disminuidas sus poblaciones como resultado de las actividades antrópicas. La información analizada sugiere que a pesar de que el grupo de los mamíferos en México es uno de los más estudiados, continúa ofreciendo interesantes retos teóricos y de manejo.Palabras clave: mamíferos marinos, mamíferos terrestres, número de especies, talla, hábitat.

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