372 Northeastern Naturalist Vol. 20, No. 2 372 Tufted Titmouse Entangled in the Burrs of Beggar’s Lice (Hackelia virginiana) Todd J. Underwood1,* and Robyn M. Underwood1 Abstract - We discovered a live Baeolophus bicolor (Tufted Titmouse) entangled in the burrs of Hackelia virginiana (Beggar’s Lice) on 28 September 2012 in Kutztown, PA. We extracted and released the titmouse because it appeared to be unable to free itself from the plant. To our knowledge, this is the second published report of a bird becoming entangled in Beggar’s Lice and the first documentation of a Tufted Titmouse becoming entangled in any plant. Entanglement in Beggar’s Lice is unusual because of the small size (3–4 mm) of its burrs. Birds occasionally fall victim to accidental entanglement in plants (Catling 2006). Most records in North America are of birds trapped in the relatively large dried fruits (hereafter burrs) of Arctium spp. L. (Burdock; Hager et al. 2009; McNicholl 1988, 1994). Here we describe entanglement of a Baeolophus bicolor (L.) (Tufted Titmouse) in the small burrs of Hackelia virginiana (L.) I.M. Johnst. (Beggar’s Lice). To our knowledge, this is the second report of a bird trapped in Beggar’s Lice and the first report of a Tufted Titmouse entangled in any plant. On 28 September 2012 at 1740 hrs (EST), while walking along the Sacony Trail in Kutztown, Berks County, PA (40°30'N, 75°46'W), we discovered a live Tufted Titmouse hanging upside down in herbaceous vegetation (Fig. 1). The bird was approximately 1Department of Biology, Kutztown University, Kutztown, PA 19530. *Corresponding author - underwoo@kutztown.edu. Figure 1. A live Tufted Titmouse entangled in the burrs of Beggar’s Lice (Hackelia virginiana) in Kutztown, PA. Photograph © T.J. Underwood. Notes of the Northeastern Naturalist, Issue 20/2, 2013 2013 Northeastern Naturalist Notes 373 1 m from the trail edge in an area where deciduous, riparian forest meets mowed grass athletic fields. A closer inspection of the titmouse revealed that its tail and both wings were entangled in the burrs of Beggar’s Lice. The wings were spread slightly, and its right wing and tail were stuck together. The titmouse was hanging from a point 84 cm above the ground on a Beggar’s Lice plant that measured 130 cm tall. We watched the bird for approximately 15 minutes to note its behavior and to determine whether it would be able to free itself. The titmouse repeatedly pecked at the stems of adjacent plants that were near its feet and occasionally gave a high frequency distress call. A couple of times it twisted its head toward its back, presumably in an unsuccessful attempt to grasp or peck at the stems/burrs that were holding it. The titmouse was badly entangled and did not appear capable of freeing itself. As R.M. Underwood approached the bird to remove it from the Beggar’s Lice, it attempted to flap its wings and wriggled its body, but was unable to free itself. We removed the burrs and released the titmouse, which flew to a nearby tree, apparently unharmed. Beggar’s Lice is a biennial plant native to eastern and central North America (USDA, NRCS 2012). It has single-sided racemes (i.e., flowering stems) with flowers that produce 3–4-mm-wide dried fruits covered in hooklets (Rhoads and Block 2007). Each dried fruit, or burr, is a cluster of four nutlets (Gleason 1952), which separate as they attach to an animal for dispersal. After extricating the titmouse, we removed eight individual flowering stems, one intact burr, and 127 individual nutlets of Beggar’s Lice from its wing and tail feathers. Thus, we estimate the bird was trapped by at least 33 separate burrs. By comparison, birds entangled in the larger burrs (≈1–4 cm) of Burdock are usually trapped by only a few individual burrs (e.g., Stensaas 1989; T.J. Underwood, pers. observ.; Zimmer and Kantrud 1987). Larger burrs have a higher contact separation force than do smaller burrs (Gorb and Gorb 2002). Therefore, plants with smaller burrs, like Beggar’s Lice, are unlikely to entrap a bird unless contact is made with a large number of burrs. Indeed, there are only a few North American records of birds entangled in plants with small burrs (e.g., Craves 1998, Hampson 1970, Mossop 1959). Only one of these reports involved birds caught in Beggar’s Lice. Hampson (1970) described a Troglodytes aedon Vieillot (House Wren) that was caught but freed itself from Beggar’s Lice and a Regulus calendula (L.) (Ruby-crowned Kinglet) that died after becoming entangled. We suspect that the titmouse was foraging among the low vegetation when it became entangled. It may have been feeding in nearby plants at the same height as the Beggar’s Lice and accidentally contacted the burrs. Other herbaceous plants in the area immediately surrounding the entanglement site included Solidago spp. (goldenrod), Geum canadense Jacq. (White Avens), Ambrosia trifida L. (Giant Ragweed), and Rubus spp. (raspberry). There were two Beggar’s Lice plants at the entanglement site and five Giant Ragweed plants within 1 m of the site. Tufted Titmice forage lower to the ground in fall and winter and eat a diet consisting of about one-third plant material (Grubb and Pravasudov 1994). Tufted Titmice also feed on Ambrosia spp. (ragweed) seeds, although these seeds make up a very small portion of their overall diet (Martin et al. 1961). On three separate days in October 2012, T.J. Underwood observed small flocks of Tufted Titmice foraging on Giant Ragweed seeds and moving through the herbaceous vegetation from just above ground level to 2 m high along the edge of the same stretch of the Sacony Trail. On 5 October 2012, three different titmice made numerous foraging trips to a Giant Ragweed plant within 1 m of the Beggar’s Lice plant that entangled the titmouse. While moving to or from the Giant Ragweed plant, the titmice often perched on raspberry canes within 30 cm of this Beggar’s Lice plant. Thus, our observations of titmice feeding around the Beggar’s Lice plant provide circumstantial evidence that 374 Northeastern Naturalist Vol. 20, No. 2 foraging likely led to this accidental entanglement. Foraging activities have also been implicated in bird entanglements in Burdock. Birds may be attracted to Burdock plants in search of seed-depredating insect larvae in the burrs (Needham 1909), seeds in the burrs (Terres 1980), or nectar produced in the flowers (Hinam et al. 200 4). Literature Cited Catling, P.M. 2006. Effects of invasive alien plants on birds: Some examples from North America. Biodiversity 6(4):30–39. Craves, J.A. 1998. Swainson’s Thrush caught in Enchanter’s Nightshade. Wilson Bulletin 110:569–570. Gleason, H.A. 1952. The New Britton and Brown Illustrated Flora of the Northeastern United States and Adjacent Canada. Vol. 3. The New York Botanical Garden, New York, NY. 595 pp. Gorb, E., and S. Gorb. 2002. Contact separation force of the fruit burrs in four plant species adapted to dispersal by mechanical interlocking. Plant Physiology and Biochemistry 40:373–381. Grubb, Jr, T.C., and V.V. Pravosudov. 1994. Tufted Titmouse (Baeolophus bicolor). No. 86, In A. Poole and F. Gill (Eds.). The Birds of North America. The Academy of Natural Sciences, Philadelphia, PA, and The American Ornithologists’ Union, Washington, DC. Hager, S.B., B. Dziadyk, and K.J. McKay. 2009. Bird-plant entanglement: A review and addition of the Least Flycatcher. Wilson Journal of Ornithology 121:648–651. Hampson, J. 1970. A kinglet tragedy. Inland Bird Banding News 42:79. Hinam, H.L., S.G. Sealy, and T.J. Underwood. 2004. Ruby-throated Hummingbird, Archilochus colubris, entanglements in burdock, Arctium spp., at Delta Marsh, Manitoba. Canadian Field- Naturalist 118:85–89. Martin, A.C., H.S. Zim, and A.L Nelson. 1961. American Wildlife & Plants: A Guide to Wildlife Food Habits. Dover Publications, Inc., New York, NY. 500 pp. McNicholl, M.K. 1988. Bats and birds stuck on burdock. Prairie Naturalist 20:157–160. McNicholl, M.K. 1994. Additional records of birds caught on burdock. Ontario Birds 12:117–119. Mossop, H. 1959. Chickadee Notes No. 247: Hummingbird tragedy. Winnipeg Free Press 9 Oct 1959:13. Needham, J.G. 1909. Kinglets captured by burdocks. Bird-Lore 11:261–262. Rhoads, A.F., and T.A. Block 2007. The Plants of Pennsylvania: An Illustrated Manual, Second Edition. University of Pennsylvania Press, Philadelphia, PA. 1042 pp. Stensaas, M. 1989. Warbler entangled in burdock. Loon 61:49. Terres, J.K. 1980. The Audubon Society Encyclopedia of North American Birds. Wings Books, New York, NY. 1109 pp. US Department of Agriculture, Natural Resources Conservation Service (USDA, NRCS). 2012. The PLANTS database. National Plant Data Team, Greensboro, NC. Available online at http:// plants.usda.gov. Accessed 2 October 2012. Zimmer, S.J., and H.A. Kantrud. 1987. Burdock traps kinglet. Prairie Naturalist 19:259–260.