Field Notes
U.S. Fish & Wildlife Service
Field Notes Entry   
Moosehorn National Wildlife Refuge Joins MOTUS Network and Nanotags Woodcock
Northeast Region, October 15, 2015
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Wildlife researchers attach a nanotag radio transmitter to an American Woodcock at Moosehorn NWR.
Wildlife researchers attach a nanotag radio transmitter to an American Woodcock at Moosehorn NWR. - Photo Credit: Ray Brown, USFWS
USGS Research Wildlife Biologist Daniel McAuley and volunteer James Petersen
USGS Research Wildlife Biologist Daniel McAuley and volunteer James Petersen "nightlighting" at Moosehorn NWR to capture American woodcock. - Photo Credit: Ray Brown, USFWS
Partially extended telescopic lattice nanotag radio telemetry tower at Moosehorn NWR.  Sensorgnome receiver is in box on side of tower.
Partially extended telescopic lattice nanotag radio telemetry tower at Moosehorn NWR. Sensorgnome receiver is in box on side of tower. - Photo Credit: Ray Brown, USFWS
Telescoping mast nanotag telemetry tower at Moosehorn NWR.
Telescoping mast nanotag telemetry tower at Moosehorn NWR. - Photo Credit: Ray Brown, USFWS

Moosehorn National Wildlife Refuge has joined the Motus Wildlife Tracking System (Motus) by erecting nanotag receiving towers and attaching tiny nanotag radio transmitters to American woodcock to study their migration patterns. Motus (http://motus-wts.org/) was established by Bird Studies Canada “to facilitate landscape-scale research and education on the ecology and conservation of migratory animals.” The Motus system consists of stationary radio receivers and other equipment necessary to detect and record the passage of migratory birds, bats, and other wildlife that have been outfitted with special “nanotag” radio transmitters by wildlife researchers.


Formerly, radio telemetry on wildlife was restricted to relatively large species to which bulky standard radio transmitters could be attached, and organisms had to be manually tracked by researchers on foot or in vehicles. Whereas that older type of radio telemetry technology is still very useful for many types of wildlife research, new technologies hold promise for increasing our understanding of wildlife movements and wildlife-habitat relationships in ways not possible with standard telemetry. Nanotag technology is one of the new technologies that may provide breakthroughs in wildlife research. The development of very small nanotag radio transmitters has enabled researchers to track much smaller wildlife species than formerly possible, such as songbirds, bats, and even some insects.

Traditional radio telemetry requires individual radio frequencies for each individual animal, thereby limiting the number of transmitters that can be deployed and animals that can be tracked at one time. In contrast, nanotag technology allows the deployment of hundreds of transmitters on the same frequency. The technology uses advanced computerized receivers and post-processing to detect slight variations in each wildlife transmitter’s frequency so that a virtually unlimited number of transmitters can be deployed simultaneously. Wildlife Researchers throughout the western hemisphere have affixed tiny nanotag transmitters to thousands of individual birds and bats in the last few years for the purpose of studying migration routes and phenology of migratory species.

One present limitation to the nanotag transmitter wildlife tracking technology is that the detection of the transmitters is typically conducted by specially designed stationary nanotag receivers attached to large, high reception antennas. Individual receivers can only detect the passage of a transmittered animal by the tower, but cannot pinpoint the animal’s precise location or habitat used by the animal. However, the technology can determine the timing and speed of migration, migratory pathways, general location and length of time of use of “stopover” habitat for resting and feeding during migration, and various other migratory factors. The precision and usefulness of the data is multiplied with the presence of multiple towers along a migratory pathway.

Nanotag receiving stations are relatively costly and time consuming to construct and maintain, and no single entity would be able to fund, get landowner permission for, or maintain a sufficient number of towers along entire migratory pathways for most migratory species to enable meaningful migration research. Researchers instead depend on cooperators within the Motus System to erect and maintain towers on their properties and to manually download data from the towers and upload the data into the Motus database. Wildlife migration data is shared within the system under a set of rules that benefits wildlife researchers and receiving station owners alike, to maximize the share of knowledge to benefit wildlife conservation.

As of January of 2016, the Motus network consisted of over 300 receiving towers throughout eastern Canada and the U.S., with most towers located on the coastlines of New Brunswick, Nova Scotia, and the eastern U.S. as well as the Great Lakes region. Additional towers are located throughout North America as far away as South Texas and the Canadian arctic. Many other towers are operated seasonally or for specific wildlife projects, including some in Central and South America.

In the fall of 2015, Moosehorn staff constructed two nanotag receiving stations on the Baring Division of the refuge. Both receiving stations consist of “sensorgnome” (https://www.sensorgnome.org/) receivers, large 9-element Yagi antennas, and special high quality radio telemetry cables to maximize signal reception. One station was deployed as a permanent fixture at the refuge’s Air Quality monitoring station and HazeCam site (http://www.hazecam.net/camsite.aspx?site=moosehorn). The antennas were attached to a special trailer-mounted 80’ telescopic lattice tower that we received on excess from NASA. We only extended the tower approximately 46’ for now to ensure that it would survive its first Maine winter unscathed. That receiver runs on A/C power from the air quality station. The second receiver was deployed in the Barn Meadow woodcock roost field as a temporary structure, but may become permanent depending on research needs. That receiver employs a 50’ telescopic mast tower, and runs on solar power. A third receiver was constructed for deployment overlooking Cobscook Bay on the coast, but logistical and weather constraints delayed the tower construction until the spring of 2016.

Immediately following the activation of the nanotag receiving stations at Moosehorn, refuge staff worked with U.S. Geological Survey Research Wildlife Biologist Daniel McAuley to attach nanotag transmitters to 24 American woodcock that were roosting in the refuge’s blueberry fields and grass fields. All 24 woodcock were detected by one or both of the refuge’s towers during the following several days and weeks. By mid-December, all of the transmittered woodcock had migrated from the area. Most of the birds were detected at other nanotag receivers in the Motus system from Midcoast Maine to Virginia as they worked their way south ahead of the winter weather. Many of the birds were detected at other coastal National Wildlife Refuges, such as Maine Coastal Islands, Rachel Carson, Rhode Island, and Eastern Shore of Virginia refuges.

Although the refuge’s nanotag receiving stations were activated at the very end of the migration period for most birds, the refuge’s towers still managed to detect an Ipswich savanna sparrow that had been tagged on Sable Island, Nova Scotia, and a northern saw-whet owl that was tagged in southwestern Nova Scotia. The Canadian researchers have requested that we keep our towers operational through the winter to detect any additional radio-marked northern saw-whet owls that may venture across the border as winter progresses.

We have already learned a tremendous amount of information about woodcock migration in the fall and early winter from the data we have received from other Motus System cooperators about our transmittered birds. As the birds move further southward and then back northward as winter waxes and wanes, we will receive more information on the birds’ movements. We hope that their transmitters will still be operational when the birds return to Moosehorn to breed in March and April so that we can continue to monitor their movements into the breeding season.

We will increase our participation in the Motus system of nanotag receivers in 2016 to include installations at other USFWS properties that are managed out of the Moosehorn headquarters office. In addition to the additional tower(s) that we will install on Moosehorn in 2016, we will also install nanotag detection station towers at Aroostook NWR in northern Maine, and Sunkhaze NWR and Carlton Pond WPA in Central Maine in 2016. These towers will be installed to detect birds and bats migrating through non-coastal portions of Maine to increase our knowledge of inland migration routes.

Contact Info: Ray Brown, 207-454-7161 x 105, ray_brown@fws.gov
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