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Habitat diversity & bat activity in vineyards

Rochelle setting up bat acoustic monitoring equipment in a Napa Vineyard
Rochelle setting up bat acoustic monitoring equipment in a Napa Vineyard

For her undergraduate honors thesis, Rochelle studied bat activity in North Coast vineyards. Using acoustic equipment, she tested whether local or landscape-scale habitat diversity influenced vineyard bat activity. Rochelle and her colleagues found that local habitat diversity significantly increased overall bat activity, especially for two of the most common bat species detected (the Yuma myotis & Big brown bat).

These species are also known to consume agricultural pests. Thus, promoting their activity in agricultural landscape will not only benefit bats, but may also help suppress agricultural pests. Rochelle’s research was published last week in the journal Agriculture, Ecosystems, and the Environment.

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Summer of Fieldwork: Grenada 2015

Grenada is a 344 Km2 island located in the Southeastern Caribbean. Despite its small size, it is famous for being one of the major producers of nutmeg and mace in the world. Exotic trees of many commercially important fruits, including the iconic Myristica fragrans, have been planted throughout the island’s mountainous landscape. For fruit bats, this means one thing: lots and lots of food.

Leith and I visited Grenada last summer thanks to an invitation to Saint George’s University by Dr. Sonia Cheetam Brow and Dr. Diana Stone. Sonia and Diana are virologists at SGU’s School of Veterinary Medicine, and they were interested in doing research on viruses that may be hosted by Grenadian bats. This research is very important because bats in Grenada are abundant and use many man-made structures for roosting, putting them in close proximity to humans. Additionally, we were interested in surveying what bat species still live in Grenada. Very few studies have characterized the island’s bat fauna and the last inventory precedes the damage caused by Hurricane Ivan to the region.

Much of our efforts went into finding bat roosting sites nearby population settlements, while at the same time spanning all of Grenada’s parishes to get a full coverage of the island major habitats. Our collaborators put a lot of effort networking with locals to find bat roosting sites. While people in Grenada are very familiar with the presence of bats, locating bat colonies proved trickier. First, there is little knowledge about natural roosts, with the exception of one small cave that is home to hundreds of Artibeus jamaicensis and Glossophaga longirostris. Second, bats are considered “pests” by most locals, and any group of roosting bats found in or near a house is usually exterminated quickly.

Luckily for us and the bats, natural disasters and economic downturns have resulted in many buildings (e.g., large vacation houses, bars, barns) to be left completely abandoned throughout the island. We found that these structures now provide new and relatively conflict-free roosts for hundreds of bats in Grenada. Walking into some of these houses felt sort of post-apocalyptic: lianas and other plants growing inside, bats hanging from the ceiling or flying around by the dozens, walls covered in guano, and floors covered in a thick layer of bat-dispersed seeds that were meant to grow in the forest.

In all, through roost searches and mistnetting, we collected only four species of the 12 that have been previously reported in Grenada: Artibeus lituratus, Artibeus jamaicensis, Glossophaga longirostris, and Molossus molossus. It is unclear if the diversity of bats has decreased due to human activity and natural disasters in the island, or if the findings are due to the need of a bigger sampling effort.

While in Grenada, we were also able to give guest lectures at SGU, talk with locals about bats, learn methods for necropsy and pathobiology sampling, and learn about the rich Grenadian history and culture. Leith and Sonia are now creating a guide to the bats of Grenada, which we hope can contribute to educating the population on the importance of bats for ecosystems and aid in their conservation.

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Summer of fieldwork: Costa Rica

In July, Jeff Riffell, David Villalobos and I went to La Selva Biological Station in Costa Rica to work on our NSF-funded project “Chance or necessity? Adaptive vs. non adaptive evolution in plant-frugivore interactions”. Going in the middle of the rainy season during an El Niño year made for a very stormy, wet, muddy and soggy couple of weeks. In what I’d like to call “the field season triathlon” (hiking, trawling, and reaching up), we were able to collect Volatile Organic Compounds (VOC) from the fruits of over a dozen species of Piper and other bat-dispersed plants, and fecal and tissue samples from nearly 100 bats. While mapping the VOC profiles onto phylogenies will enable us to investigate how fruit scent evolves in this system, analyses of the bat fecal samples will allow us to expand our current understanding of how much the bats rely on the different Piper species for food.

This autumn, Leith Miller and Ada Kaliszewska are continuing sample collection and analysis for this project in La Selva. Meanwhile, Laurel Yohe (a PhD student at our collaborating lab) gave a talk at the North American Symposium for Bat Research in which she presented preliminary results  on the olfactory receptors of short-tailed fruit bats.

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Summer of fieldwork: The Philippines

Time flies when you’re having fun, or if you are catching bats around the world, which is basically the same thing. This is the first post reporting our fieldwork trips this summer, which included four countries across four ecogeographic regions!

It all started with a trip to the Philippines with a team composed by the Sears, Dávalos, Dumont and Santana labs, Dr. Susan Tsang, and colleagues from the National Museum of the Philippines. Our main goal was to collect Old World fruit bats (Pteropodidae) for a study that will contribute to understanding why these bats have much lower cranial diversity than their New World counterparts (Phyllostomidae). Answering this question involves integrating studies on cranial development, bite force and feeding behavior across a range of pteropodid and phyllostomid species.

What impressed me the most upon arriving to the Philippines was the overwhelming population density (Luzon is the 4th most populated island in the world). Our field sites were near, Liliw, a highland town in the southern portion of the Laguna province. Even several hours away from the capital, there were no apparent sights of the kind of habitats that I would expect could sustain bats. Yet, despite the loss of habitat and the pollution, some bat species still seem to fly through this landscape and take advantage of fruiting trees during their nightly foraging activities. Using mist nets suspended a few dozen meters above the ground, and skipping on any form of night sleep, we were able to collect five of these bat species: Cynopterus brachyotis, Eonycteris spelaea, Macroglossus minimus, Ptenochirus jagori, and Rousettus amplexicaudatus. Though this was a considerably lower diversity than what I’m used to experiencing in the Neotropics, it was astonishing to see these species live for the first time.

From the beginning, it was quite evident that pteropodids are a different ballgame than phyllostomids when it comes to recording performance and feeding behavior. Although both Cynopterus and Ptenochirus were reminiscent of Neotropical Artibeus species in their extravagant use of distress calls in the mist net, their approach towards scary things (like a bite force meter) seemed quite different. These species, as well as the rest of the pteropodids we caught, tended to rely more on their flight response when faced with experimental situations – cue adorable bat covering its face with its wings. With much patience and creativity, however, we were able to get bite force data for new species to complement previous datasets for our study. Likewise, Karen Sears and Dan Urban set up a lab in the field that allowed them to conduct unprecedented experiments and observations on the skull development of several pteropodid species.

My favorite catch of this trip was Rousettus, despite the fact that their activity peaked between 2-4 AM, sending the sleep-deprived team into panic mode to quickly release dozens of bats from the nets before sunrise. Rousettus were extremely gentle bats, and it was a treat to hear their tongue clicks (a form of echolocation) as they flew about and while we handled them. The young of at least one species of Rousettus may learn vocalizations in similar ways to the way human babies do. What’s not to love?

The data and samples collected during this trip will serve for dozens of studies that will expand the understanding of this diverse and still obscure group of bats. As it often happens, I came back with many more research questions than when I left. Here’s to hoping there will be more pteropodids in our future.

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Bat blitz!

How hard does a pallid bat bite?
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!

 

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New NSF grant to study bat-plant coevolution!

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

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Notes from the Field: Moses Coulee

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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Notes from the field: Vendovi Island

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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Notes from the field: La Selva

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!

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The muscles behind the bite force: bat muscles in 3D

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.