SHORT COMMUNICATIONS The Wilson Journal of Ornithology 119(2):27 1-275, 2007 Incidence of Nest Material Kleptoparasitism Involving Cerulean Warblers Kelly C. Jones,l Kirk L. Roth,' Kamal Paul B. HameL2 and Carl G. Smith, 1112 ABSTRACT.-We document 21 observations of in- terspecific stealing of nesting material involving Ce- rulean Warblers (Dendroica cerulea), Red-eyed Vireos (Vireo olivaceus), Blue-gray Gnatcatchers (Polioptila caerulea), Northern Parulas (Parula americana), Black-throated Green Warblers (D. virens), American Redstarts (Setophaga ruticilla), and Orchard Orioles (Zcterus spurius) that occurred during studies of Ce- rulean Warbler breeding biology. These incidents in- volved a variety of combinations of nest owner and nest material thief suggesting that each of these species is both a perpetrator and recipient of this behavior in our study areas. Kleptoparasitic incidents occurred at all stages of the nesting cycle from nest-building through post-fledging. Two possible motivations for this behavior are related to saving time in finding nest materials and collecting this material for nest construc- tion. Received 21 November 2005. Accepted 3 Septem- also been observed gathering nesting materi- als from vireo nests (species unspecified) in New Jersey (Dater 195 1). Cerulean Warbler breeding biology studies have focused on nest observation beginning in 1992 in Tennessee and Arkansas, and in 2002 in southern Indiana. This paper documents 21 interspecific contests for nesting material in- volving Cerulean Warblers that were observed during stages of the nesting cycle (Table 1). We present three detailed accounts of nest ma- terial kleptoparasitism involving Cerulean Warblers as both victim and perpetrator. Own- er defense usually started at the point at which the owner discovered the robber at its nest. ber 2006. OBSERVATIONS The Cerulean Warbler (Dendroica cerulea) is a canopy-nesting bird of eastern deciduous forests. Nests of this species are composed mainly of bark fiber, fine grass stems, weed stalks, hairs, spider webs, grapevine bark, li- chen, and moss (e-g., Bent 1953, Ehrlich et al. 1988, Oliarnyk and Robertson 1996, Harnel 2000). Nests are typically on horizontal branches and are concealed from above by nest-tree and/or vine foliage (Bent 1953, Ha- me1 2000, Roth 2004). Few published studies have documented interspecific nest kleptopar- asitism involving Cerulean Warblers. Hamel (2000) noted in the Mississippi Alluvial Val- ley that Cerulean Warblers and American Redstarts (Setophaga ruticilla), and Cerulean Warblers and Blue-gray Gnatcatchers (Poliop- tila caerulea) interacted aggressively over nesting materials. Cerulean Warblers have ' Department of Biology, Ball State University, Muncie, IN 47306, USA. USDA, Forest Service, Center for Bottomland Hardwoods Research, I? 0. Box 227, Stoneville, MS 38776, USA. The following two accounts document nest material kleptoparasitism with the Cerulean Warbler as victim. The first incident occurred on 19 May 2003 between 1230 and 1300 hrs CST when a Red-eyed Vireo (Vireo olivaceus) was observed taking material from a Cerulean Warbler nest in a grove of black walnut (Jug- lans nigra) at Big Oaks National Wildlife Ref- uge (39" 03' N, 85" 25' W) near Madison, In- diana. The vireo landed on the nest branch within a meter of the nest, then flew to the nest and removed a piece of the outer cup when the Cerulean Warbler was not present. The nest material was sufficiently large to be seen in the vireo's beak as it flew to a more densely wooded area. No bird visited the nest for a period of several minutes until a vireo again landed on the nest branch. The vireo hopped toward the nest when the male Ceru- lean Warbler chased it into the heavily wood- ed area. The female Cerulean Warbler then flew to the nest and sat in it. The female Ce- rulean Warbler was first observed building the nest on 8 May and incubating on 17 May. She was last observed incubating on 29 May and Corresponding author; e-mail: kislam@bsu.edu the nest had failed on 3 1 May. The walnut 272 THE WILSON JOURNAL OF ORNITHOLOGY Vol. 119, No. 2, June 2007 TABLE 1. Nest material kleptoparasitism involving Cerulean Warblers recorded during Cerulean Warbler breeding biology studies in Tennessee, Arkansas, New York, and Indiana. Study area Date Nest owner Stage Kleptoparasite Meeman Shelby Forest, TN Meeman Shelby Forest, TN Meeman Shelby Forest, TN Meeman Shelby Forest, TN Meeman Shelby Forest, TN Chickasaw NWR, TN Chickasaw NWR, TN Chickasaw NWR, TN Chickasaw NWR, TN Desha, AR Desha, AR Desha, AR Meeman Shelby Forest, TN Yellowwood State Forest, IN Meeman Shelby Forest, TN Desha, AR Desha, AR Big Oaks NWR, IN Ulster County, NY (Smith 2001) Hoosier National Forest, IN Meeman Shelby Forest, TN 9 May 93 15 May 93 16 May 93 23 May 97 24 May 97 7 Jun 93 22 May 94 23 May 94 5 Jun 94 11 May 93 13 May 93 28 May 93 10 Jun 93 29 May 05 1 1 May 94 14 May 93 27 Jul 93 19 May 03 26 May 99 6 May 05 11 May 93 Cerulean Warbler Cerulean Warbler Cerulean Warbler Cerulean Warbler Cerulean Warbler Cerulean Warbler Cerulean Warbler Cerulean Warbler Cerulean Warbler Cerulean Warbler Cerulean Warbler Cerulean Warbler Cerulean Warbler Cerulean Warbler Cerulean Warbler Cerulean Warbler Cerulean Warbler Cerulean Warbler Red-eyed Vireo Red-eyed Vireo Blue-gray Gnat- catcher Building Building Abandoned Building Building Building Incubation Immediately after depreda- tion Abandoned Abandoned Dismantling and Cerulean Warbler reconstructing Dismantling and Cerulean Warbler reconstructing Incubation Building Building Incubation Unknown Incubation Abandoned Building Immediately after depreda- tion American Red- start American Red- start American Red- start American Red- start American Red- start Blue-gray Gnat- catcher Blue-gray Gnat- catcher Blue-gray Gnat- catcher Blue-gray Gnat- catcher Blue-gray Gnat- catcher Blue-gray Gnat- catcher Blue-gray Gnat- catcher Blue-gray Gnat- catcher Black-throated Green Warbler Northern Parula Orchard Oriole Orchard Oriole Red-eyed Vireo Cerulean Warbler Cerulean Warbler Cerulean Warbler grove had an open canopy, permitting detailed observations of the birds' behavior. The second incident occurred on 29 May 2005 between 1 030 and 1 1 30 hrs when a fe- male Black-throated Green Warbler (Dendroi- ca virens) was observed taking material from a Cerulean Warbler nest in Yellowwood State Forest (39" 12' N, 86" 21' W) near Blooming- ton, Indiana. It landed on the nest branch within 1 m of the nest, approached it in a quick hopping manner, and stole nest material. The female Black-throated Green Warbler re- peated this behavior three times and each time she was chased from the nest by the female Cerulean Warbler. In one of the three inci- dents, a male Cerulean Warbler was observed chasing with the female Cerulean Warbler. Eventually, both male and female Cerulean Warblers exhibited aggressive behavior (mak- ing repeated harsh call notes and chasing) to- " SHORT COMMUNICATIONS 273 ward the female Black-throated Green War- bler any time she perched within 15 m of the nest. The male Black-throated Green Warbler was not observed participating in chasing or nest robbing. The Cerulean Warbler nest was in a red elm (Ulmus rubra) near a planting of shortleaf (Pinus echinata) and eastern white pine (P. strobus). This may have increased the chances of proximity to a Black-throated Green Warbler territory, as that species is of- ten associated with coniferous forests (Morse 1993). The following account describes nest ma- terial kleptoparasitism with Cerulean Warbler as the perpetrator. On 6 May 2005 between 1430 and 1500 hrs a female Cerulean Warbler was observed taking material from a Red-eyed Vireo nest in the Pleasant Run Unit of the Hoosier National Forest (39" 01 ' N, 86" 20' W) near Bloomington, Indiana. The Cerulean Warbler made three separate trips from its own nest to the vireo nest approximately 30 m to the east, each time successfully acquiring material. On the first trip, the vireo presum- ably did not detect the Cerulean Warbler, as no interaction occurred; however, the vireo gave chase on the warbler's second and third trips. The stolen material was sufficiently large to be seen in the Cerulean Warbler's beak, and was incorporated into its nest. Both the Cerulean Warbler and the Red-eyed Vireo nests appeared to be mostly completed at the time of the raid. Construction of the Cerulean Warbler nest was first observed on 4 May 2005 at 1230 hrs; on 26 May 2005 the nest was confirmed to have failed. DISCUSSION The studies in which these ob'servations oc- curred were specifically focused on Cerulean Warbler nests and it is not surprising that most incidents (18 of 21 observations, Table 1) in- volved Cerulean Warblers as victims rather than perpetrators. Most observations of female Cerulean Warblers returning to their nests with nesting material did not include observ- ing them collect the material. Therefore, Ce- rulean Warblers may be robbing other nests more often than we are aware. Red-eyed Vireos and Black- throated Green Warblers are not unlikely participants for nest material thievery interactions with Cerulean Warblers. Red-eyed Vireos are one of the most abundant bird species in our study areas (KCJ and KLR, pers. obs.), and both Red-eyed Vir- eos and Black-throated Green Warblers forage at the same heights where Cerulean Warbler nests occur (Morse 1993, Cimprich et al. 2000). Additionally, and perhaps most impor- tantly, Cerulean Warblers, Red-eyed Vireos, and Black-throated Green Warblers may have similar requirements for nest composition and compete for materials. Red-eyed Vireos have been documented to use all of the same ma- terials as Cerulean Warblers, with the excep- tion of moss, in their nests (Harrison 1975, Ehrlich et al. 1988, Cimprich et al. 2000). Black-throated Green Warblers have been documented to use all materials except grape- vine bark and lichen (Ehrlich et al. 1988, Morse 1993). Prolonged completion of nest building may indicate that nest robbing has taken place, as was likely the case in the second nest robbing account. In this case, the Cerulean Warbler nest was probably not the pair's first attempt of the season based on the late date of nest construction. They began building their sec- ond nest on 25 May 2005, four days before nest robbing was observed. Immediately prior to observing nest material kleptoparasitism, the female Cerulean Warbler was seen bring- ing nesting material to her nest. As replace- ment nests are typically constructed more quickly than first nests, a 5-day spread of nest building was unexpected (KCJ and KLR, pers. obs.). Despite the interference, the nest suc- cessfully fledged at least two offspring. Why would individuals risk physical con- flict with neighboring birds to steal nesting material? It is possible that (1) some materials may take a great amount of time to locate, and (2) some materials may not be difficult to lo- cate, but may be difficult to remove and col- lect in quantity in an appropriate size or shape to be incorporated into a nest (Yezerinac 1993). Nest material may be in limited supply, as a result of the large demand for it by a variety of users, or the phenology of the source is limited in time. Nest construction is a time- consuming process, as it requires the adult bird to locate materials, to gather the materials into the nest site, and to form the actual nest. Nest construction appears to be a costly pro- cess in terms of energy expenditure. This pro- 274 THE WILSON JOURNAL OF ORNITHOLOGY Vol. 119, No. 2, June 2007 cess involves a multitude' of flights to gather material. Bent (1953) indicated a single fe- male American Redstart might make 700 trips in the construction of a single nest. The fe- male pulls material from sources, such as dried cambium of broken tree branches and grapevines, even from inner portions of stems of herbaceous materials. The female must identity the most useful adhesive materials for attaching nests to supports and for holding surfaces together. "Spider webs" or silk from cocoons of emerged moths are often listed as the adhesive material. A variety of types of spider silk exist; variation among species may indicate that some may be more useful than others and the possibility of discriminate se- lection by avian users (Gosline et al. 1999, gurovec and Sehnal 2002). Early nesting be- havior may in part be favored by the ability to find the most effective nest materials. Com- petition for materials that are limited in time may occur between users of the favored ma- terial, irrespective of cost considerations. Benefits of stealing nest materials are sub- stantial reductions in (1) distance the female must travel from her nest, (2) time spent away f r o m her nest, and/or (3) amount of effort spent while away from the nest. Birds may be more likely to resort to time-saving nest klep- toparasitism because the benefits outweigh the risks. The Red-eyed Vireo and the Black- throated Green Warbler may have robbed Ce- rulean Warbler nests because of the pressure of time during what was probably (based on the time of season) their second nesting at- tempt. Another potential benefit of engaging in nest kleptoparasitism is decreased predation risk. Nest building birds may experience in- creased predation risk when gathering so much material in such a short period of time, often from relatively few locations which are repeatedly visited. Canopy-nesting species other species, including but not limited to birds, mammals, snakes, and parasitic insects, may also observe locations frequented by nest building birds. Banks and Martin (2001) noted that when visitations by nest owner decreased in frequency, rates of Brown-headed Cowbird (Molothrus ater) nest parasitism increased. Therefore, less time spent foraging for nesting materials would allow the female more time for activities such as egg-laying and nest guarding. All of these factors, acting individually or in concert, indicate that time of nest construc- tion is a critical part of the life cycle of a bird, when the most important reproductive activi- ties, including mate selection and egg produc- tion, occur. Study of the process is difficult, particularly for small species that nest in tree canopies in forest habitats. It is difficult to ob- serve canopy-nesting species gathering nest- ing materials. Consequently, few data exist on predation risks associated with gathering nest material and the propensity to avoid certain locations as sites for gathering material. It is not clear exactly how advantageous or disadvantageous kleptoparasitism of nest ma- terial is to individuals which participate in it. The perpetrators in all three detailed accounts presented, consistently returned to the victim- ized nests, despite the threat of being chased, indicating the rewards of kleptoparasitism out- weighed the risks. One of the two Cerulean Warbler nests that was raided was successful. This indicates that victimization did not ne- cessitate failure. The Cerulean Warbler pair that stole from the vireo nest was unsuccessful in raising young despite any benefits obtained from nest robbing. Further studies on nest rob- bing behavior, as related to the phenology, availability, and selection of nest materials will contribute to our understanding of when a nest-building female engages in nest mate- rial kleptoparasitism. must often resort to gathering nesting material near or on the ground. These sites are not typ- ACKNOWLEDGMENTS ical for the species; the birds may have less We thank the u.S. Fish and Wildlife Service, U.S. experience with the potential escape routes Forest Service, Sigma Xi, Indiana Academy of Sci- from predators available in such situations. ence, Garden Club of America, and Ball State Univer- The large number of to and from a nest sity Office of Academic Research and Sponsored Pro- grams for funding support. Work in Tennessee and Ar- site increases the likelihood that a nest para- kansas was supported by the U.S. Forest Service and site may observe the location, follow the pro- initiated by P. Smith and R. G . Cooper. We ac- gress of the construction, and time their Par- knowledge the dedication to accurate field observation asitic laying event. It is equally possible that displayed by Roger Allan, David Arbour, Bob Ford, SHORT COMMUNICATIONS 275 Jenna Hestir, Dawn Hinebaugh, Cary Leiper, Matt Marshall, Curt McCasland, Darren Pierce, Melinda Schaefbauer, Larry Wood, Chris Woodson, and Rich Young, whose observations form the substance of this report. Our manuscript was greatly improved by the comments and suggestions of Carol Ann Islam, Sarah Jones, three anonymous reviewers, and the editor. LITERATURE CITED BANKS, A. J. AND T E. MARTIN. 2001. Host activity and the risk of nest parasitism by Brown-headed Cowbirds. Behavioral Ecology 12:3 1-40. BENT, A. C. 1953. Life histories of North American wood warblers. Part 1. U.S. National Museum Bulletin 203. CIMPRICH, D. A., E R. MOORE, AND M. P. GUILFOYLE. 2000. Red-eyed Vireo (Vireo olivaceus). The birds of North America. Number 527. DATER, E. E. 1951. First successful nesting of the Ce- rulean Warbler in New Jersey. Wilson Bulletin 63: 115-1 16. EHRLICH, P R., D. S. DOBKIN, AND D. WHEYE. 1988. The birder's handbook: a field guide to the natural history of North American birds. Simon and Schuster, New York, USA. GOSLINE, J. M., P A. GUERETTE, C. S. ORTLEPP, AND K. N. SAVAGE. 1999. The mechanical design of spider silks: from fibroin sequence to mechanical function. Journal of Experimental Biology 202: 3295-3303. HAMEL, P B. 2000. Cerulean Warbler (Dendroica cer- ulea). The birds of North America. Number 51 1. HARRISON, H. 1975. A field guide to the birds' nests. Houghton Mifflin, Boston, Massachusetts, USA. MORSE, D. H. 1993. Black-throated Green Warbler (Dendroica virens). The birds of North America. Number 55. OLIARNYK, C. J. AND R. J. ROBERTSON. 1996. Breeding behavior and reproductive success of Cerulean Warblers in southeastern Ontario. Wilson Bulletin 108:673-684. ROTH, IS. L. 2004. Cerulean Warbler breeding biology. Thesis. Ball State University, Muncie, Indiana, USA. SMITH, G. C. 111. 2001. Breeding Cerulean Warblers (Dendroica cerulea) in Esopus and West Park, U1- ster County, New York. Thesis. State University of New York at New Paltz, New Paltz, USA. YEZERINAC, S. M. 1993. American Redstarts using Yel- low Warblers' nests. Wilson Bulletin 105:529-531. ZUROVEC, M. AND E SEHNAL. 2002. Unique molecular architecture of silk fibroin in the waxmoth, Gal- leria mellonella. Journal of Biological Chemistry 277 : 22639-22647. The Wilson Journal of Ornithology 119(2):275-279, 2007 Home Range and Dispersal of Juvenile Florida Burrowing Owls Robert J. Mryka10,l.~ Melissa M. Grigione,' and Ronald J. Sarno2 ABSTRACT-We present the first use of necklace telemetry capabilities. Aerial telemetry assisted in lo- radio transmitters to document the home range and dis- cating one juvenile Burrowing Owl using scrub oak persal of juvenile Burrowing Owls (Athene cunicularia (Quercus spp.) habitat approximately 10.1 krn southeast JEoridana) during the breeding and post-breeding period of its main and satellite burrows. Received 16 Februaly in rural Florida. Juvenile Burrowing Owls (n = 4) were 2006. Accepted 7 October 2006. detected close to main and satellite burrows during 65 day-time relocations. Home range estimates (95% ker- nel) for juvenile owls varied from 98 to 177 m2. Juvenile Burrowing Owls were not detected near main and sat- ellite burrows during three evening relocations. Dis- persal of juvenile owls coincided with flooding of bur- rows during the rainy season. Juvenile owls upon fledg- ing used an extensive patch of saw palmetto (Serenoa repens) before dispersing beyond the range of ground Department of Environmental Science and Policy, University of South Florida, 4202 E. Fowler Ave., Tampa, FL 33620, USA. Department of Biology, University of South Florida, BSF 206,4202 E. Fowler Ave., Tampa, FL 33620, USA. Corresponding author; e-mail: rnrykalo @hotmail.com Early observations of Florida Burrowing Owls (Athene cunicularia jloridana) describe their propensity to excavate burrows in short grass habitat (Hoxie 1889, Rhoads 1892, Scott 1892, Palmer 1 896). Typically, a breeding pair of owls excavate one breeding burrow and one or more satellite burrows (Scott 1892, Neil1 1954, Wesemann 1986, Mealey 1997). Bur- rows, which can be 1-3 m in length, contain an enlarged nest chamber at their terminus (Rhoads 1892, Scott 1892, Nicholson 1954, Sprunt 1954). Male and female Florida Bur- rowing Owls can breed at l year of age (Haug