Behavioral and Ecological Influences on the Echolocation of Brazilian Free-Tailed Bats, \u3cem\u3eTadarida brasiliensis\u3c/em\u3e

This dissertation investigates variability in the echolocation calls of Brazilian free-tailed bats, Tadarida brasiliensis (Chiroptera: Molossidae), and explores how bats adjust echolocation call structure in response to different behavioral and ecological conditions. Substantial geographic variation exists in the echolocation call structure of T. brasiliensis throughout the species range in the US, but this variation does not correlate with geographic or climatic patterns. Most variation in call structure is due to differences between and within the calls of individuals. When exposed to broadcasts of high frequency insect sounds, free-flying bats consistently responded by shifting call frequencies away from the broadcast frequencies. This response suggests that bats are sensitive to local acoustic interference that decreases the efficiency of echo reception. In another investigation of reactions to interfering sounds, bats responded to echolocation playbacks by rapidly shifting their call frequencies away from playback frequencies, indicating that a jamming avoidance response was occurring. Bats more frequently shifted their calls upwards to higher frequencies, which may be due to maximal jamming power of the lower frequency portion of echolocation calls. Flexibility in their echolocation calls also was evident in calls produced by T. brasiliensis while emerging from roosts in a tight column formation. Bats emitted two distinct call types during emergence, sweep and hook calls, which were substantially different from foraging calls. Call structure differed between roosts, which may be related to differences in the spacing of bats within emergence columns. In a final experiment, it was found that bat activity was substantially greater in response to echolocation playbacks that contained feeding buzz calls compared to broadcasts that did not contain these signals, indicating that bats eavesdrop on the echolocation calls of conspecifics. Overall, this study documents the highly flexible nature of echolocation in Brazilian free-tailed bats and demonstrates that bats respond acoustically to behavioral and ecological influences

Cooperative signaling behavior of roost location in a leaf-roosting bat

Research suggests that social calls are important for conveying information about food and roost location in bats. However, no studies have specifically documented calls that are used to actively attract conspecifics to roosting locations. Here we describe the cooperative signaling behavior of roost location towards flying conspecifics in Spix’s disc-winged bat (Thyroptera tricolor), a species that uses a highly ephemeral roosting resource. Two types of calls were recorded during field experiments; one from flying individuals termed “inquiry calls”, and another from roosting bats termed “response calls”. Inquiry calls were emitted by flying bats immediately upon release, and quickly elicited production of response calls from roosting individuals. Most flying bats entered the roost when roosting individuals responded, while very few bats entered the roost in the absence of a response. During playback experiments, we found significant differences in response rates among individuals, which could be caused by diverse intrinsic and extrinsic factors. In addition, results of our ongoing field studies suggest that the cooperative signaling behavior of roost location is important in maintaining social cohesion, and that the use of a larger home range when resources are scarcer may decrease group stability by hindering communication.UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biologí

Mammals of North Dakota. First edition. Robert Seabloom.

As a mammalogist living in the Great Plains, I was excited to hear about the publication of The Mammals of North Dakota by Robert Seabloom. No such field guide has been compiled since the late 1920s, leaving nature lovers and researchers alike without a modern source of information about the mammals of the state. Despite my enthusiasm, I will admit that I was originally expecting a standard (i.e., boring) field guide with dry facts about the taxonomic groups of interest. Much to my surprise, this book was not a mere list of relevant information, but an engaging work providing extensive background on the regional mammalian fauna. I was especially impressed how Seabloom managed to couch the important and relevant facts about each species in a broader context, permitting the reader to develop a rich understand- ing of the landscapes and ecosystems found in North Dakota. The book begins by giving the reader some background information on the Class Mammalia, including a helpful section that lists not only the taxonomy of extinct and extant mammalian groups, but also offering a brief description of each order and where these animals are found. Such information is useful for nature enthusiasts and hobby biologists, who may have little background information about the order. An introductory section, written by John Hoganson, a paleontologist with the North Dakota Geological Survey, provides a fascinating description of the mammalian paleo- fauna of North Dakota. Hoganson paints a picture of how the mammals of the state have changed over geological time, beginning with the small, inconspicuous rodent-like animals of the Cretaceous to the giant ground sloths and woolly mammoths of the Pleistocene. He also provides information about the diversity of North Dakota’s landscapes and how these have changed over time, including shallow oceans, forested swamplands, and savanna

Mammals of North Dakota. First edition. Robert Seabloom.

As a mammalogist living in the Great Plains, I was excited to hear about the publication of The Mammals of North Dakota by Robert Seabloom. No such field guide has been compiled since the late 1920s, leaving nature lovers and researchers alike without a modern source of information about the mammals of the state. Despite my enthusiasm, I will admit that I was originally expecting a standard (i.e., boring) field guide with dry facts about the taxonomic groups of interest. Much to my surprise, this book was not a mere list of relevant information, but an engaging work providing extensive background on the regional mammalian fauna. I was especially impressed how Seabloom managed to couch the important and relevant facts about each species in a broader context, permitting the reader to develop a rich understand- ing of the landscapes and ecosystems found in North Dakota. The book begins by giving the reader some background information on the Class Mammalia, including a helpful section that lists not only the taxonomy of extinct and extant mammalian groups, but also offering a brief description of each order and where these animals are found. Such information is useful for nature enthusiasts and hobby biologists, who may have little background information about the order. An introductory section, written by John Hoganson, a paleontologist with the North Dakota Geological Survey, provides a fascinating description of the mammalian paleo- fauna of North Dakota. Hoganson paints a picture of how the mammals of the state have changed over geological time, beginning with the small, inconspicuous rodent-like animals of the Cretaceous to the giant ground sloths and woolly mammoths of the Pleistocene. He also provides information about the diversity of North Dakota’s landscapes and how these have changed over time, including shallow oceans, forested swamplands, and savanna

Distribution and Occurrence of Bat Species in North Dakota

Prior to 2009, a detailed survey of occurrence and distribution of bats in North Dakota had not been conducted. Localized surveys, occurrence reports, and museum specimens provided the only records of bats in the state. Ongoing habitat loss, exploitation of natural resources, and the impending spread of white-nose syndrome to the western United States are major threats to bat populations of the region. The objective of this study was to document presence and distributions of bat species resident in North Dakota. From 2009 to 2012, multiple mist-netting and acoustic surveys were conducted to document species presence across North Dakota. A total of 68 sites across 5 ecological regions were surveyed, with a capture total of 333 bats. The presence of 11 species was confirmed in the state. The occurrences of Corynorhinus townsendii and Myotis thysanodes represent substantial range expansions beyond previously reported species distributions, as well as the first capture of M. thysanodes in North Dakota. We also report issues with acoustic identification of M. septentrionalis and highlight the importance of using multiple sampling methods, especially for species of conservation concern. The results of this study will be valuable for informing state managers about the conservation needs of North Dakota’s bat populations, as well as providing baseline information for future research on bat populations within the state

Data from: Sound amplification by means of a horn-like roosting structure in Spix's disc-winged bat

While sound is a signal modality widely used by many animals, it is very susceptible to attenuation, hampering effective long-distance communication. A strategy to minimize sound attenuation that has been historically used by humans is to use acoustic horns; to date, no other animal is known to use a similar structure to increase sound intensity. Here, we describe how the use of a roosting structure that resembles an acoustic horn (the tapered tubes that form when new leaves of plants such as Heliconia or Calathea species start to unfurl) increases sound amplification of the incoming and outgoing social calls used by Spix's disc-winged bat (Thyroptera tricolor) to locate roosts and group members. Our results indicate that incoming calls are significantly amplified as a result of sound waves being increasingly compressed as they move into the narrow end of the leaf. Outgoing calls were faintly amplified, probably as a result of increased sound directionality. Both types of call, however, experienced significant sound distortion, which might explain the patterns of signal recognition previously observed in behavioural experiments. Our study provides the first evidence of the potential role that a roost can play in facilitating acoustic communication in bats

Cooperative signaling behavior of roost location in a leaf-roosting bat

Research suggests that social calls are important for conveying information about food and roost location in bats. However, no studies have specifically documented calls that are used to actively attract conspecifics to roosting locations. Here we describe the cooperative signaling behavior of roost location towards flying conspecifics in Spix’s disc-winged bat (Thyroptera tricolor), a species that uses a highly ephemeral roosting resource. Two types of calls were recorded during field experiments; one from flying individuals termed “inquiry calls”, and another from roosting bats termed “response calls”. Inquiry calls were emitted by flying bats immediately upon release, and quickly elicited production of response calls from roosting individuals. Most flying bats entered the roost when roosting individuals responded, while very few bats entered the roost in the absence of a response. During playback experiments, we found significant differences in response rates among individuals, which could be caused by diverse intrinsic and extrinsic factors. In addition, results of our ongoing field studies suggest that the cooperative signaling behavior of roost location is important in maintaining social cohesion, and that the use of a larger home range when resources are scarcer may decrease group stability by hindering communication

In-Flight Social Calls: A Primer for Biologists and Managers Studying Echolocation

Recent technological advances have permitted collection of immense datasets through automated recordings that are primarily aimed at capturing bat echolocation. Analyses of echolocation calls are used to identify species, relative abundance and some aspects of behaviour, such as foraging or commuting. Here we propose that social calls recorded in flight are also valuable tools for understanding bat ecology and behaviour. First, we examine how and why the acoustic structure of social calls differ from echolocation. Differences in form make social calls often, but not always easy to identify. We then use a case study on in-flight song in Tadarida brasiliensis (Geoffroy, 1824), to show that what may appear as echolocation may instead be predominantly used for social communication. Next, we review three basic functions of in-flight social calls, include examples of each and develop a framework for testing these alternative functions using automated recordings. In a second case study, we use automated recordings of the endangered Florida bonneted bat (Eumops floridanus (Allen, 1932) to illustrate how behavioural information can be gleaned by examining patterns of social call production. Finally, we discuss why and how social calls provide novel information that can be crucial for conservation and management efforts.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Strong individual signatures and weaker group signatures in contact calls of Spix’s disc-winged bat, Thyroptera tricolor

Spix’s disc-winged bats, Thyroptera tricolor, form small, long-term social groups in which members are loyal to a patch of forest but move on a daily basis between highly ephemeral roosting sites (partly unfurled Heliconia leaves). This species has been shown to exchange social calls that facilitate contact with nearby bats and recruitment to roost sites. During flight, T. tricolor emits ‘inquiry’ calls that frequently elicit a response from individuals that have already entered a furled leaf. These ‘response’ calls are then followed by the flying bat entering the occupied leaf roost. In this study, we examined variation in the structure of inquiry and response calls, and assessed whether calls encode information about individual or group identity that would allow for acoustic discrimination to occur. We found that both inquiry and response calls were sufficiently consistent within individuals, and divergent between individuals, to permit separation of individual bats based on call structure. We also found some evidence for group-specific signatures, although these were less defined than differences observed between individuals. While this does not confirm that Spix’s disc-winged bats can discriminate between individuals and groups based on call information, our results indicate that both call types have a broad enough parameter space for this to occur.North Dakota State University///Estados UnidosNational Science Foundation/[ADVANCE Institutional Transformation Grant HRD-0811239]//Estados UnidosUCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de BiologíaUCR::Sedes Regionales::Sede de Occident