Novel predator recognition by Allenby's gerbil (Gerbillus andersoni allenbyi ): do gerbils learn to respond to a snake that can “see” in the dark?

Unlike desert rodents from North America, Allenby’s gerbil (Gerbillus andersoni allenbyi) from the Negev Desert, Israel has evolved with snakes that do not have heat-sensitive sensory pits that enhance night vision. Does this history affect their ability to assess and respond to a snake that has this ability? As a test, we exposed gerbils to risk of predation from various predators, including snakes, owls, and foxes. The snakes included the Saharan horned viper (Cerastes cerastes) and the sidewinder rattlesnake (Crotalus cerastes). The former snake lacks sensory pits and shares a common evolutionary history with the gerbil. The latter snake, while convergent evolutionarily on the horned viper, has sensory pits and no prior history with the gerbil. The gerbils exploited depletable resource patches similarly, regardless of snake species and moon phase. While the gerbils did not respond to the novel snake as a greater threat than their familiar horned viper, the gerbils were cognizant that the novel predator was a threat. In response to both snakes, giving-up densities (GUDs; the amount of food left in a resource patch following exploitation) of the gerbils were higher in the bush than open microhabitat. In response to moonlight, GUDs were higher on full than on the new moon. Based on GUDs, the gerbils responded most to the risk of predation from the red fox, least from the two snake species, and intermediate for the barn owl. Keywords:US-Israel Binational Science Foundation (BSF) [BSF-2008163]12 month embargo; Published online: 13 May 2016This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Appendix A. ANOVA tables showing how season and gerbil state affect owl attacks, owl attack duration, gerbil GUDs, and gerbil cumulative time analyses.

ANOVA tables showing how season and gerbil state affect owl attacks, owl attack duration, gerbil GUDs, and gerbil cumulative time analyses

Behavioral responses during feather replacement in house sparrows

Birds lose feathers, whether during molt or by accident, and replace them by processes that are energetically demanding. We hypothesized that house sparrows Passer domesticus biblicus use behavioral means to save energy when feathers are lost, and tested the general prediction that house sparrows growing new feathers adjust their behavior to minimize the energy costs of foraging and to increase net energy gain from their food. To test these predictions we divided 18 house sparrows into three groups: 1) plucked – house sparrows from which we plucked 15 flight feathers; 2) cut – house sparrows in which the same 15 feathers were cut off at the calamus below the barbs; and 3) control – unmanipulated house sparrows with plumage intact. We recorded both the quantity of seeds the house sparrows ate and the time they spent foraging from assay food patches. We found that ‘plucked’ sparrows growing new feathers adjust their foraging behavior by reducing their feeding time and the number of visits to a food patch. This allowed them to increase their patch harvest rate while maintaining a steady body mass

Divergent behavior amid convergent evolution: A case of four desert rodents learning to respond to known and novel vipers.

Desert communities world-wide are used as natural laboratories for the study of convergent evolution, yet inferences drawn from such studies are necessarily indirect. Here, we brought desert organisms together (rodents and vipers) from two deserts (Mojave and Negev). Both predators and prey in the Mojave have adaptations that give them competitive advantage compared to their middle-eastern counterparts. Heteromyid rodents of the Mojave, kangaroo rats and pocket mice, have fur-lined cheek pouches that allow them to carry larger loads of seeds under predation risk compared to gerbilline rodents of the Negev Deserts. Sidewinder rattlesnakes have heat-sensing pits, allowing them to hunt better on moonless nights when their Negev sidewinding counterpart, the Saharan horned vipers, are visually impaired. In behavioral-assays, we used giving-up density (GUD) to gauge how each species of rodent perceived risk posed by known and novel snakes. We repeated this for the same set of rodents at first encounter and again two months later following intensive "natural" exposure to both snake species. Pre-exposure, all rodents identified their evolutionarily familiar snake as a greater risk than the novel one. However, post-exposure all identified the heat-sensing sidewinder rattlesnake as a greater risk. The heteromyids were more likely to avoid encounters with, and discern the behavioral difference among, snakes than their gerbilline counterparts.US-Israel Binational Science Foundation [BSF-2008163]; US-Israel Binational Science Foundation (BSF) [BSF-2008163]; Ben Gurion University of the Negev Ethics in Animal Research Committee [IL-73-11-2009]Open access journal.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Appendix A. Model selection tables ranking the best models to explain the foraging behavior of gerbils.

Model selection tables ranking the best models to explain the foraging behavior of gerbils

Foraging behaviour in East Asian desert rodents and its implications on coexistence

<p>We studied the foraging behaviour of two sympatric rodents (<i>Meriones meridianus</i> and <i>Dipus sagitta</i>) in the Gobi Desert, Northwestern China. The role of the foraging behaviour in promoting species coexistence was also examined. We used giving-up densities (GUDs) in artificial food patches to measure the patch use of rodents and video trapping to directly record the foraging behaviour, vigilance, and interspecific interactions. Three potential mechanisms of coexistence were evaluated (1) microhabitat partitioning; (2) spatial heterogeneity of resource abundance with a tradeoff in foraging efficiency vs. locomotion; and (3) temporal partitioning on a daily scale. Compared to <i>M. meridianus</i>, <i>D. sagitta</i> generally possessed lower GUDs, spent more time on patches, and conducted more visits per tray per capita, regardless of microhabitat. However, <i>M. meridianus</i> possessed advantages in average harvesting rates and direct interference against <i>D. sagitta</i>. Our results only partly support the third mechanism listed above. We propose another potential mechanism of coexistence: a tradeoff between interference competition and safety, with <i>M. meridianus</i> better at interference competition and <i>D. sagitta</i> better at avoiding predation risk. This mechanism is uncommon in previously studied desert rodent systems.</p

Novel predator recognition by Allenby's gerbil (Gerbillus andersoni allenbyi): do gerbils learn to respond to a snake that can “see” in the dark?

Unlike desert rodents from North America, Allenby’s gerbil (Gerbillus andersoni allenbyi) from the Negev Desert, Israel has evolved with snakes that do not have heat-sensitive sensory pits that enhance night vision. Does this history affect their ability to assess and respond to a snake that has this ability? As a test, we exposed gerbils to risk of predation from various predators, including snakes, owls, and foxes. The snakes included the Saharan horned viper (Cerastes cerastes) and the sidewinder rattlesnake (Crotalus cerastes). The former snake lacks sensory pits and shares a common evolutionary history with the gerbil. The latter snake, while convergent evolutionarily on the horned viper, has sensory pits and no prior history with the gerbil. The gerbils exploited depletable resource patches similarly, regardless of snake species and moon phase. While the gerbils did not respond to the novel snake as a greater threat than their familiar horned viper, the gerbils were cognizant that the novel predator was a threat. In response to both snakes, giving-up densities (GUDs; the amount of food left in a resource patch following exploitation) of the gerbils were higher in the bush than open microhabitat. In response to moonlight, GUDs were higher on full than on the new moon. Based on GUDs, the gerbils responded most to the risk of predation from the red fox, least from the two snake species, and intermediate for the barn owl. Keywords:US-Israel Binational Science Foundation (BSF) [BSF-2008163]12 month embargo; Published online: 13 May 2016This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]