Big data in wildlife research: remote web-based monitoring of hibernating black bears

Abstract

Background: Numerous innovations for the management and collection of "big data" have arisen in the field of medicine, including implantable computers and sensors, wireless data transmission, and web-based repositories for collecting and organizing information. Recently, human clinical devices have been deployed in captive and free-ranging wildlife to aid in the characterization of both normal physiology and the interaction of animals with their environment, including reactions to humans. Although these devices have had a significant impact on the types and quantities of information that can be collected, their utility has been limited by internal memory capacities, the efforts required to extract and analyze information, and by the necessity to handle the animals in order to retrieve stored data.

Results: We surgically implanted miniaturized cardiac monitors (1.2 cc, Reveal LINQ™, Medtronic Inc.), a newly developed human clinical system, into hibernating wild American black bears (N = 6). These devices include wireless capabilities, which enabled frequent transmissions of detailed physiological data from bears in their remote den sites to a web-based data storage and management system. Solar and battery powered telemetry stations transmitted detailed physiological data over the cellular network during the winter months. The system provided the transfer of large quantities of data in near-real time. Observations included changes in heart rhythms associated with birthing and caring for cubs, and in all bears, long periods without heart beats (up to 16 seconds) occurred during each respiratory cycle.

Conclusions: For the first time, detailed physiological data were successfully transferred from an animal in the wild to a web-based data collection and management system, overcoming previous limitations on the quantities of data that could be transferred. The system provides an opportunity to detect unusual events as they are occurring, enabling investigation of the animal and site shortly afterwards. Although the current study was limited to bears in winter dens, we anticipate that future systems will transmit data from implantable monitors to wearable transmitters, allowing for big data transfer on non-stationary animals.

Figure 1

Wireless telemetry system at bear den. The insertable cardiac monitor (ICM) communicated with a relay station housed in a waterproof container via an antenna buried under the bear. Transmissions to an internet site were via a cellular module attached to a timber tripod fabricated at the site. The system was powered by 12 volt batteries charged by a solar panel.

Figure 2

Three generations of implantable monitors used by this research team. Device A has a volume of 80 cc [17], device B a volume of 9 cc [18], and device C (used in this current study) a volume of 1.2 cc. A millimeter ruler is included as a size reference.

Figure 3

Image of website used for data tracking and display. The subject bears were enrolled into a web-based clinic as patients. The site served as both a repository for data and as a means of tracking transmissions. In addition, the site automatically alerted the user when an event of interest occurred.

Figure 4

Example near-real time data acquired from denning bears. A dramatic reduction in activity and heart rate variability was observed in pregnant females post parturition (such as 4011 shown here), whereas a constant level of activity and heart rate variability was maintained throughout the winter for the female denning with yearlings (4067). (Note: To calculate heart rate variability, the device measures each ventricular interval and calculates the median interval every 5 min. The heart rate variability value (in ms) for each day is then calculated as the variability seen in the 5-minute median values over the 24-hour period [19]).

Figure 5

Sample ECG plots acquired from denning bears. The top two panels show the minimum (16-second pause) and maximum heart rates (222 beats/minute) recorded during the study period. Both were recorded from bear 4067. The maximum rate occurred the day following our visit to the den and is believed to be associated with a subsequent visit to the den by the landowners. A 5-second pause is shown for bear 4061 in the third recording and the bottom two recordings include myograms relating to skeletal muscle activity (during the period of birthing for 4011 and post-parturition for 4021).

Figure 6

Telemetry system covered by snow drift. The bear at this site, which was denned in an open nest, relocated after our December visit. The site was exposed to heavy winds, causing the telemetry box and solar panel (left panel) to be covered by 2 m of snow in early March (right panel). Author Iaizzo appears in the left side of both photos and author Laske is standing on the black telemetry box in the right panel.