12 results
Now showing1 - 10 of 12
- Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Thinking small: Next-generation sensor networks close the size gap in vertebrate biologging(2020-04-01); ; ; ; Recent advances in animal tracking technology have ushered in a new era in biologging. However, the considerable size of many sophisticated biologging devices restricts their application to larger animals, whereas older techniques often still represent the state-of-the-art for studying small vertebrates. In industrial applications, low-power wireless sensor networks (WSNs) fulfill requirements similar to those needed to monitor animal behavior at high resolution and at low tag mass. We developed a wireless biologging network (WBN), which enables simultaneous direct proximity sensing, high-resolution tracking, and long-range remote data download at tag masses of 1 to 2 g. Deployments to study wild bats created social networks and flight trajectories of unprecedented quality. Our developments highlight the vast capabilities of WBNs and their potential to close an important gap in biologging: fully automated tracking and proximity sensing of small animals, even in closed habitats, at high spatial and temporal resolution.Publicationtype: Journal ArticleScopus© Citations 48 50 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Low-Weight Noninvasive Heart Beat Detector for Small Airborne VertebratesIn this letter, a low-weight and low-power noninvasive ECG heart beat detector for pulse analysis in small vertebrates is proposed and verified on bats. To achieve this low weight, the ECG front end is optimized for low space requirements and low energy consumption, drawing only 30 μA. The complete system, including the system on chip for recording and wireless data transmission, requires 3.3 mA in active mode. Since only a small battery with a weight of 0.6 g is used, this low power consumption is necessary to still be able to reach a continuous measurement time of more than 6 h. Compared to other solutions, this newly proposed system gathers data via noninvasive electrodes while still achieving a high signal quality and, at the same time, is light enough to allow airborne measurements without affecting the animal's behavior.Publicationtype: Journal Article90 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Vampire Bats that Cooperate in the Lab Maintain Their Social Networks in the Wild(2019-12-02); ; ; ; Social bonds, maintained by mutual investments of time and energy, have greatly influenced the evolution of social cognition and cooperation in many species [e.g., 1–8]. However, there are two pitfalls regarding “social bonds” as an explanation for social structure and cooperation [1, 9–11]. First, studies often incorrectly assume that frequent association implies partner fidelity based on mutual social preference, but even seemingly complex nonrandom interaction networks can emerge solely from habitat or spatial structure [12–16]. Second, the false appearance of partner fidelity can result from stable options in the “partner market” [1, 9–11, 17]. For instance, individuals might preferentially groom the same partner, even if the decision depends entirely on the immediate costs and benefits rather than relationship history. Given these issues, a key challenge has been testing the extent to which social structure is driven by the intrinsic relationship history versus the extrinsic physical and social environment. If stable bonds exist, they should persist even if the individuals are moved to a dramatically different physical and social environment. We tested this prediction by tracking social relationships among common vampire bats (Desmodus rotundus) moved from the lab to the wild. We show that allogrooming and food sharing among female vampire bats induced in captivity over 22 months predicted their assortativity and association rates when we subsequently tracked them in the wild with custom-made high-resolution proximity sensors. The persistence of many relationships across different physical and social environments suggests that social structure is caused by both extrinsic constraints and intrinsic partner fidelity.Publicationtype: Journal Article81 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Wireless Sensor Platform for Detection of Vital Parameters of Bats(2019-07); ; ; ; In this paper an advanced sensor node for animal tracking is proposed, which includes an accelerometer, an air pressure sensor as well as an electrocardiography sensor. The system is designed for studying the physiology and behavior of bats by inferring activity, wing beat frequency as well as heart rate. This system offers outstanding functionality compared to other tracking nodes and is easily applicable thanks to its noninvasive design. Gluing the sensor to the bat's back keeps the impact on the animal at a minimum and retrieval of the animal to remove the tag is not required since the tag falls off after a few days.Publicationtype: Conference PaperScopus© Citations 2 113 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Non-Invasive Low Power ECG for Heart Beat Detection of Bats(2019-05-09); ; ; ; In this paper a small size low power electrocardiogram (ECG) system which is optimized for the heart rate detection of bats is proposed. Due to the smaller size and different physical properties of animals like bats the system has to fulfill different requirements than standard human ECGs. The usecase of animal monitoring also requires an ultra-low power approach to enable long battery runtime. The described system has been evaluated with measurements on bats and compared to a commercially available ECG integrated circuit (IC). Apart from the ECG circuit itself the electrodes and the electrode position as well as the used algorithms are evaluated.Publicationtype: Conference Paper73 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Proximity sensors on common noctule bats reveal evidence that mothers guide juveniles to roosts but not food(2019-02-01); ; ; ; Female bats of temperate zones often communally rear their young, which creates ideal conditions for naive juveniles to find or learn about resources via informed adults. However, studying social information transfer in elusive and small-bodied animals in the wild is difficult with traditional tracking techniques. We used a novel 'next-generation' proximity sensor system (BATS) to investigate if and how juvenile bats use social information in acquiring access to two crucial resources: suitable roosts and food patches. By tracking juvenile - adult associations during roost switching and foraging, we found evidence for mother-to-offspring information transfer while switching roosts but not during foraging. Spatial and temporal patterns of encounters suggested that mothers guided juveniles between the juvenile and the target roost. This roost-switching behaviour provides evidence for maternal guidance in bats, a form of maternal care that has long been assumed, but never documented. We did not find evidence that mothers guide the offspring to foraging sites. Foraging bats reported brief infrequent meetings with other tagged bats that were best explained by local enhancement. Our study illustrates how this recent advance in automated biologging provides researchers with new insights into longstanding questions in behavioural biology.Publicationtype: Journal Article86 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , BATS: adaptive ultra low power sensor network for animal tracking(Multidisciplinary Digital Publishing Institute (MDPI), 2018-10-07); ; ; ; In this paper, the BATS project is presented, which aims to track the behavior of bats via an ultra-low power wireless sensor network. An overview about the whole project and its parts like sensor node design, tracking grid and software infrastructure is given and the evaluation of the project is shown. The BATS project includes a lightweight sensor node that is attached to bats and combines multiple features. Communication among sensor nodes allows tracking of bat encounters. Flight trajectories of individual tagged bats can be recorded at high spatial and temporal resolution by a ground node grid. To increase the communication range, the BATS project implemented a long-range telemetry system to still receive sensor data outside the standard ground node network. The whole system is designed with the common goal of ultra-low energy consumption while still maintaining optimal measurement results. To this end, the system is designed in a flexible way and is able to adapt its functionality according to the current situation. In this way, it uses the energy available on the sensor node as efficient as possible.Publicationtype: Journal Article278 271 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Low-weight wireless sensor node for animal encounter detection and dual-band localization(2016-03-30); ; ; ; In this paper the feasibility of encounter detection and simultaneous localization of bats in their natural habitat is demonstrated. Furthermore a compact design of an enhanced mobile node exhibiting a weight of only 1.85 g is presented. The new design allows for an increased robustness of the localization by implementing dual-band signal transmission at 2.4GHz and in the sub-gigahertz range. The prolongation of operation time up to 14 days and beyond is discussed in detail.Publicationtype: Conference Paper79 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Automated proximity sensing in small vertebrates: design of miniaturized sensor nodes and first field tests in bats(Wiley, 2016-03-02); ; ; ; Social evolution has led to a stunning diversity of complex social behavior, in particular in vertebrate taxa. Thorough documentation of social interactions is crucial to study the causes and consequences of sociality in gregarious animals. Wireless digital transceivers represent a promising tool to revolutionize data collection for the study of social interactions in terms of the degree of automation, data quantity, and quality. Unfortunately, devices for automated proximity sensing via direct communication among animal-borne sensors are usually heavy and do not allow for the investigation of small animal species, which represent the majority of avian and mammalian taxa. We present a lightweight animal-borne sensor node that is built from commercially available components and uses a sophisticated scheme for energy-efficient communication, with high sampling rates at relatively low power consumption. We demonstrate the basic functionality of the sensor node under laboratory conditions and its applicability for the study of social interactions among free-ranging animals. The first field tests were performed on two species of bats in temperate and tropical ecosystems. At <2 g, this sensor node is light enough to observe a broad spectrum of taxa including small vertebrates. Given our specifications, the system was especially sensitive to changes in distance within the short range (up to a distance of 4 m between tags). High spatial resolution at short distances enables the evaluation of interactions among individuals at a fine scale and the investigation of close contacts. This technology opens new avenues of research, allowing detailed investigation of events associated with social contact, such as mating behavior, pathogen transmission, social learning, and resource sharing. Social behavior that is not easily observed becomes observable, for example, in animals living in burrows or in nocturnal animals. A switch from traditional methods to the application of digital transceiver chips in proximity sensing offers numerous advantages in addition to an enormous increase in data quality and quantity. For future applications, the platform allows for the integration of additional sensors that may collect physiological or environmental data. Such information complements social network studies and may allow for a deeper understanding of animal ecology and social behavior.Publicationtype: Journal Article151 189 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , From radio telemetry to ultra-low-power sensor networks: Tracking bats in the wild(2016-01-01); ; ; ; Sensor networks have successfully been used for wildlife monitoring and tracking of different species. When it comes to small animals such as smaller birds, mammals, or even insects, the current approach is to use extremely lightweight RF tags located using radio telemetry. A new quantum leap in technology is needed to overcome this limitation and enable new ways to observe larger numbers of small animals. In an interdisciplinary team, we are working on the different aspects of such a new technology. In particular, we report on our findings on a sensor-network-based tracking solution for bats. Our system is based on integrated localization and wireless communication protocols for ultra-lowpower systems. This requires coding techniques for improved reliability as well as ranging solutions for tracking hunting bats. We address the technological and methodical problems related to system design, software support, and protocol design. First field experiments have been conducted that showcase the capabilities of our system.Publicationtype: Journal Article84