How hard does a pallid bat bite?
Leith & Rochelle headed up to Canada last weekend to help with a Bat Blitz. This year, the objective was to inventory the bat diversity within a Nature Conservancy preserve in the Okanagan valley of British Columbia.
Over three nights, we documented 10 of the 14 species known to occur in the area. On the last night we participated, we finally caught a pallid bat – a rare and exciting catch. These bats are known to feed on large ground dwelling arthropods, including scorpions, and sometimes even small lizards! How much force is needed to access such hard prey items? Even though a few of the biologists felt force of this pallid’s bite, when we attempted to measure his bite force he was unwilling to perform.
While we had to leave the following morning, the blitz continued another night, and we hope they were able to document more of the diversity of this valuable preserve. We can only hope the next time we catch a pallid bat, the first thing he will chomp down on is our bite force meter!
We are thrilled to announce that our NSF collaborative proposal has been awarded! Together with the Dávalos lab at SUNY Stony Brook and the Riffell lab at UW, we will be working on the project “Chance or necessity? Adaptive vs. non adaptive evolution in plant-frugivore interactions”. We will investigate the coevolution between fruit scents and the olfactory ability and behavioral preferences of fruit-eating bats by integrating advanced tools from analytical chemistry, genomics, and behavioral ecology. Our work will focus on two ecologically important groups of tropical plants and mammals, Piper plants and Carollia bats, and will be based at La Selva Biological Station in Costa Rica. We are currently looking for a postdoc and recruiting a Ph.D. student for this project.
Photo © Merlin Tuttle, BCI
Rochelle, Jeff and I headed out to Moses Coulee to catch bats in the shrub-steppe. The primary goal of this trip was to be guest researchers for an Urban Conservation course through the Doris Duke Conservation Scholars program. We took the students out mist-netting and showed them what it was like to be a real bat researcher. Even though time was limited, we had success the first night out! We caught two amazing species, the Canyon bat (Parastrellus hesperus) and the Townsend’s big-eared bat (Corynorhinus townsendii). This group of students was extremely interested in many aspects of bat research: from managing museum collections, to emerging research and basic biology of bats.
This excursion also allowed us to set up some of our new equipment, a triple high mist-net that Rochelle and I lovingly named “Monster”. We ventured out for a second night of mist-netting, “Monster” in hand, with the optimistic hope of catching a Spotted bat (Euderma maculatum). We did not succeed in netting a spotted bat, but we did catch a Pallid bat (Antrozous pallidus) which was also very exciting! Overall this was a successful trip for us to see the diversity of species in a different part of the state and to help spread awareness about bat ecology, conservation and research.
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Gearing up for this summers’ field work! Last week Sharlene, Abby, Jim and I set out to conduct a pilot survey of the bats on the Vendovi Island preserve. In collaboration with the San Juan Preservation Trust, a local non-profit land trust, we carried two nights of surveys to begin documenting the bat diversity on this 217 acre island. This was an excellent opportunity to help the trust in their broader efforts to document the biodiversity on this island preserve. It was also a valuable opportunity for me to kick start my research on the San Juan Islands, which I will be starting in July on San Juan and Orcas Island.
Over our two-night survey, we captured bats 2 of the 10 species documented to occur throughout the archipelago. Surprisingly, all of the bats we caught were males. So, is Vendovi Island a bachelor pad for bats? Our surveys were too limited to say for now. I hope to return later in the season, as maternity colonies begin to form to assess whether females, and other bat species also inhabit the island. For more information about the biodiversity of Vendovi Island or the San Juan Preservation Trust, click here.
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Leith, Rochelle, and an adorable Ectopylla alba
La Selva has been a fascinating place to visit. While Rochelle and I both had impressions of what a tropical rainforest would be like, we were both amazed at the lush, complex habitat and the organismal diversity that goes along with it. For me, I learned an extensive amount, not only about the ecological dynamics in the wet rainforest, but also more about the diversity of bats. We had the wonderful opportunity to work with Dr. Gloriana Chaverri. She gave us an opportunity to study the acoustic properties of neotropical bat distress calls, (primarily phyllostomids). Then, we conducted playback experiments to investigate how surrounding bats (intraspecifics and interspecifics) respond to these calls . In addition to our research, we were also busy working with Day’s Edge Production to produce a short film portraying the story of our research experience at La Selva. Check out the link below to see our video!
A lot of our current lab work has been focused on 3D modeling of the muscles involved in opening and closing the jaw in Neotropical leaf-nosed bats. We use iodine to stain cranial soft tissues, which enhances contrast before taking microCT scans of different bat species. This allows us to image the anatomy in great detail, and to study the muscle proportions and attachments in these very small mammals prior to dissecting the muscles. We can then segment out individual muscles and create 3D meshes that can be implemented in our bite force models! The slideshow below shows a raw, black-and-white coronal scan slice through the head of a frog-eating bat, Trachops cirrhosus, and several images of the reconstructed 3D jaw adductors.
Ectophylla alba, the Honduran white bat, is a unique species of Neotropical leaf-nosed bat. Not only they are among the very few species of bats that are almost completely white, but they are extremely specialized in their diets and roosting ecology. Males and females of the species skillfully construct delicate tents from the leaves of Heliconia plants, and their diet is restricted to fruits of Ficus colubrinae plants. During our most recent trip to Costa Rica, we had the opportunity to record and measure these bats as they frantically fed from a F. colubrinae fruiting tree (below). Fruiting events in Ficus plants occur in short bursts and are scattered throughout the landscape, and E. alba likely choose places to “camp out” according to the potential for food availability.
Previous research in vertebrates has demonstrated that selection can cause rapid evolutionary changes in cranial modularity, that is, how many and which parts of the skull vary and evolve together. Mammals, however, seem to have maintained a simple pattern of cranial modularity throughout their evolutionary history and across tremendous ecological and morphological diversity. All mammals studied to date have two cranial modules, the braincase and rostrum. But what happens when parts of the skull acquire novel functions? Does cranial integration remain the same? We just published a study in which we test whether skull modularity has been remodeled in rhinolophid bats due to the novel and critical function of their nasal cavity in echolocation. Rhinolophids have greatly enlarged nasal cavities that vary in shape across species, thus we predicted that nasal echolocation resulted in the evolution of a third cranial module, the ‘nasal dome’, in addition to the braincase and rostrum modules. Remarkably, despite large variation in the shape of the nasal dome, we found that the integration of the rhinolophid skull still follows the two-module pattern found in other mammals. In other words, the shape of the nasal cavity changes together with the shape of the snout across species. We also found distinct trends in the evolution of skull shape across these bats’ geographic distribution. Our findings highlight that broad morphological and functional diversity can still be achieved in spite of a relatively simple modular template.
Does nasal echolocation influence the modularity of the mammal skull? – Santana & Lofgren (2013) – Journal of Evolutionary Biology
After the Belize warm up, I went to Costa Rica to work at two main sites, the Tirimbina Forest Reserve and OTS La Selva research station. The major goal of this trip was to collect fecal samples for molecular dietary analyses in foliage-gleaning bats, along with performance data across bats and other mammals. These data will allow us to understand patterns and mechanisms of food resource partitioning within and across dietary guilds. With the help of collaborator Dr. Bernal Rodríguez Herrera and his students at the Universidad de Costa Rica, we were able to collect data for a total of 24 species of bats, plus several kinkajous.
One of the trip highlights included catching Honduran white bats (Ectophylla alba), a very small frugivore that builds tents in the vegetation. Findings about Ectophylla’s tent construction behavior have changed the paradigm that only male bats build these roosts as part of a resource-defense polygynous system; female Ectophylla also contribute to building tents. A second high point was collecting a wrinkle-faced bat (Centurio senex), a very rare and morphologically derived stenodermatine that is built to bite. Just as impressive, the second largest bat in the Neotropics (Phyllostomus hastatus) made its appearance in our nets and contributed to our dataset. With such stunning biodiversity, we are very much looking forward to continue work and collaborations in Costa Rica. Pura vida!
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