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A video probe system to inspect red-cockaded woodpecker cavities by David M. Richardson, Johnny W. Bradford, Peter G. Range, and John Christensen The red-cockaded woodpecker (Picoides borealis) is an endangered species restricted to the southern pine ecosystems of the southeastern United States. The species depends on living pine trees in which to construct nest and roost cavities. Traditionally, cavities have been monitored, using a small drop light and mirror, to record reproductive information. Other researchers have used a fiberscope (Purcell 1997). Both methods require that trees be climbed, which is very labor-intensive and time-consuming. Ouchley et al. (1994) and Proudfoot (1996) described miniature, pole-mounted video systems to examine open bole nests and owl nest boxes. However, these systems were built in-house, and neither design was suitable to examine red-cockaded woodpecker cavities because the camera housing would not fit into the cavity entrance. We report the use of the TreeTop Peeper(tm) II, a commercially available, pole-mounted video system, to inspect red-cockaded woodpecker cavities and determine nest stage or contents of cavities from the ground. During April-July 1997, we inspected red-cockaded woodpecker cavities to locate nests or determine other contents on Noxubee National Wildlife Refuge, Noxubee County Public School land, land of the Barge Lumber Company, and Georgia-Pacific Company timberlands located in Noxubee, Oktibbeha, and Winston counties, Mississippi, and on Carolina Sandhills National Wildlife Refuge, Chesterfield County, South Carolina. We recorded the height of each cavity and the time required to raise the video probe to the cavity, determine cavity content, and lower the pole for each cavity. In addition, for cavities inspected in Mississippi, we recorded the amount of time to climb red-cockaded woodpecker nest cavities using Swedish ladders. We examined active red-cockaded woodpecker clusters on a 1-2-week schedule to locate nests. Once we located a nest, we inspected the cavity with the camera 1-2 additional times to determine nest success and age of nestlings for banding at 6-10 days of age. To aid in determining number of nestlings, we turned the camera off and on quickly to elicit a begging response by the nestlings. We inspected cavities slightly higher than 15.2 m while standing on the roof of a pickup truck parked next to the cavity tree. The TreeTop Peeper(tm) II (Christensen Designs, Manteca, Calif.) consisted of a micro-video camera probe, LCD monitor, and cable spool attached to a telescoping pole (Figure 1). The camera probe head consisted of a plastic camera housing (3.05 cm diameter by 5.0 cm long) encapsulating a Watec 660-37 black-and-white video camera (Watec America Corp., Las Vegas, Nev.) with a tiny 2-lux, 2,000-hour white light source. The video camera comes with a set focal length of 3.7 cm and a horizontal field of view of 52°. The light source was sufficient to view cavities 46 cm deep. The camera probe was attached to a 0.79-cm-diameter fiberglass rod, which allowed inspection of cavities with a 20-cm-long entrance tunnel. The camera probe head was conical in shape on both ends, which facilitated easy insertion and extraction of the probe from both natural and artificial cavities (Copeyon 1990, Allen 1991). The camera probe weighed approximately 230 g and was attached by a plastic mount to a 15.2-m fiberglass telescoping pole (Hastings Fiber Glass Products Inc., Hastings, Mich.). The video camera was electronically connected to the ground-level video monitor and power source by a lightweight cable. The cable was managed by a small (10-cm) plastic spool with a rotary electric feed-through (Mercotach #331), Mercotach Inc., Carlsbad, Calif.) to pass power and video signals through the spool hub, which was clamped to the pole. This allowed for efficient handling of the 16 m of cable connecting the remote video camera to the ground-level monitor. Video images are viewed on a Citizens M-938 (9.7-cm diagonal) LCD monitor with sunshade (CBM America, Santa Monica, Calif.) mounted at eye level on the spool assembly. A video loop on the electronic chassis allows loop-through recording of the video signal with a video cassette recorder. A 7.0-amp, 12-volt gel-cell battery powered the camera and monitor and fit in a web belt-pouch carried by the observer. The battery supplied 8 hours of continuous power and was rechargeable overnight. Total cost of the unit was $3,950. We examined >450 cavities from 172 active and inactive clusters with the TreeTop Peeper II to locate red-cockaded woodpecker nests or examine cavities for other contents (Figures 2, 3). We located and monitored nests from 123 active clusters with the TreeTop Peeper II. Cavities ranged in height from 1.8 to 16.7 m. It took 0.5-5 minutes to examine cavities with the video camera. In contrast, 30 red-cockaded nests that were climbed with ladders, ranging in height from 6 to 16.7 m, took 5-50 minutes to inspect. We determined content of all cavities examined with the TreeTop Peeper II without climbing the tree. Presence of pine straw in the cavity was used to indicate use by the southern flying squirrel (Glaucomys volans) if the squirrel was not seen. Besides nests of red-cockaded woodpeckers, other cavity contents included: southern flying squirrel, eastern gray squirrel (Sciurus carolinensis), wood duck (Aix sponsa), eastern screech owl (Otus asio), red-bellied woodpecker (Melanerpes carolinus), red-headed woodpecker (M. erythrocephalus), white-breasted nuthatch (Sitta carolinensis), tree frog (Hyla spp.), rat snake (Elaphe obsoleta), corn snake (E. guttata), and water. The TreeTop Peeper II was an efficient means to rapidly examine red-cockaded woodpecker cavities or other cavity contents and record nesting chronology. The image quality was more than adequate to determine cavity contents. The video system has numerous advantages over using ladders and a drop light and mirror. These include: (1) increase in number of cavities examined with reduced disturbance to nesting red-cockaded woodpeckers, (2) only 1 person is needed, versus 2 for assistance and safety with ladders, (3) the field of view of the cavity chamber is much larger than that seen by looking at a mirror, (4) multiple cavities on different side of a tree can be inspected readily, whereas ladders often need to be repositioned, (5) people who are afraid of heights or physically incapable of climbing can collect cavity content data from the ground, and (6) reduced overall costs to obtain red-cockaded woodpecker nesting information. Only a few problems arose while using the TreeTop Peeper II. A simple modification was needed to reduce stress to the male-female connector near the camera probe. We taped the wire to the pole near the connector to prevent stressing the wire and had no further breaks of the wire. During windy days, and when inspecting cavities >10.7 m, increased patience and steadiness were necessary to position the probe into the cavity entrance. Small movements of the pole at the ground were greatly accentuated at the height of the probe. The commercial availability of a more rigid pole would eliminate this problem. In addition, a pole of 18.2 m would likely enable inspection of nearly 95% of red-cockaded woodpecker cavities across the species' range. Another limitation of the system was our inability to easily distinguish sex of red-cockaded woodpecker nestlings with the black-and-white camera. After approximately 15 days of age, the red crowns of the males appear grayish in contrast to the surrounding black feathers; the crowns of females appear all black. This shade difference required close inspection of the monitor and could be confused with the white appearance of the apteria on the crown of younger birds. Future development of small, affordable, color video cameras will allow easier sex determination of red-cockaded woodpecker nestlings. Nonetheless, the TreeTop Peeper II has application for researchers and managers investigating an enormous number of cavity or open bole nesting species of birds and mammals and provides an opportunity to inspect cavities in snags that are dangerous to climb. Acknowledgments. We thank L.W. Burger (Mississippi Department of Wildlife and Fisheries, GIS Lab) for assistance in electronic capture of video images. G. Askins, B. Blihovde, A. Christensen, M. Copeland, and R. Ingram provided valuable assistance with this project. Editorial assistance from G. Cotton, B. Leopold, L. Andrews, and an anonymous reviewer improved earlier drafts of the manuscript. Allen, D.H. 1991. An insert technique for constructing artificial red-cockaded woodpecker cavities. United States Forest Service General Technical Report SE-73. Copeyon, C.K. 1990. A technique for constructing cavities for the red-cockaded woodpecker. Wildlife Society Bulletin 18:303-311. Ouchley, K., R.B. Hamilton, and S. Wilson. 1994. Nest monitoring using a micro-video camera. Journal of Field Ornithology 65:410-412. Proudfoot, G.A. 1996. Miniature video-board camera used to inspect natural and artificial nest cavities. Wildlife Society Bulletin 24:528-530. Purcell, K.L. 1997. Use of a fiberscope for examining cavity nests. Journal of Field Ornithology 68:283-286. David M. Richardson is a wildlife biologist with the United State Fish and Wildlife Service at Noxubee National Wildlife Refuge. He received a B.S. degree in wildlife ecology from Unity College in Maine and an M.S. in wildlife ecology from Mississippi State University. His current work centers on implementing recovery tasks for the red-cockaded woodpecker, investigating rat snake predation of red-cockaded woodpecker nests, and wood duck ecology. Johnny W. Bradford is a biological technician at Noxubee National Wildlife Refuge. His interests include managing waterfowl and the red-cockaded woodpecker. Peter G. Range is a biological technician for the United State Fish and Wildlife Service. He did course work in biological sciences at East Tennessee State University. He is an avid birder and interested in studying neotropical migrants, especially painted buntings. John J. Christensen has over 30 years of experience in design engineering, including 11 years in the United State Nuclear Submarine Navy and 12 years at the Lawrence Livermore National Laboratory. At Christensen Designs, he uses an integrated design approach with his expertise in optical an elctro-mechanical engineering to develop wildlife research tools in the areas of audio-video and remote power systems.
Address for David M. Richardson and Johnny W. Bradford: United States Fish and Wildlife Service, Noxubee National Wildlife Refuge, Route 1, Box 142, Brooksville, MS 39739, USA. Address for Peter G. Range: United State Fish and Wildlife Service, Carolina Sandhills National Wildlife Refuge, McBee, SC 29101, USA. Address for John Christensen: 349 Scenic Place, Manteca, CA 95337, USA. Present address for Peter G. Range: United State Fish and Wildlife Service, Savannah Coastal Refuges, 1000 Business Center Drive, Parkway Business Center, Suite 10, Savannah, GA 31405, USA. |
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