FRONTISPIECE. This is a reproduction of an original watercolor by George M. Sutton painted in 1952 as an illustration for the book, Georgia , written by Thomas D. Burleigh and published by University of Oklahoma Press. The original paintings for the book were given in friendship to Herbert Stoddard and are part of the Stoddard Collection at Tall Timbers Research Station & Land Conservancy. ‘‘When I made this painting, the were not moving through the tops in noisy family groups, as they often do, but nesting quietly. This pair had a nest in a small hollowed-out cypress knee placed for them on a fence post. I looked a long while before finding exactly the right shortleaf pine branch for the picture. I wanted the branch, as well as the birds, to be interesting.’’ Published by the Wilson Ornithological Society

VOL. 119, NO. 1March 2007 PAGES 1–150

The Wilson Journal of Ornithology 119(1):1–8, 2007

COOPERATIVE BREEDING IN THE BROWN-HEADED

JAMES A. COX1,3 AND GARY L. SLATER2

ABSTRACT.—We monitored two color-marked populations of the Brown-headed Nuthatch (Sitta pusilla) for Ն5 years and collected data on survival, dispersal, territoriality, and cooperative breeding. Adults (n ϭ 284) were sedentary, maintained long-term pair bonds, and had higher apparent annual survival (66–78%) than previously reported. Territories monitored (n ϭ 347) contained up to five adults; the percentage of territories containing Ͼ2 adults averaged ϳ20% but varied widely. Most groups with Ͼ2 adults consisted of a breeding pair and a male helper related to at least one breeding adult (n ϭ 8), but several exceptions were noted. The presence of helpers did not improve nest productivity. Apparent annual survival for females was lower than apparent survival for males in one population and may have influenced cooperative breeding. In the other population, apparent survival was similar between males and females. We suggest food resources and other environmental factors may have influenced cooperative breeding in this setting. Received 19 January 2006. Accepted 21 July 2006.

Cooperative breeding in the Brown-headed that inhabits open pine (Pinus spp.) forests in Nuthatch (Sitta pusilla) has received little at- the southeastern United States and the Baha- tention since the behavior was first described mas. Populations have declined steadily by Norris (1958). Presumably non-breeding throughout much of the species’ range (Sauer adult nuthatches spend large amounts of time et al. 2005) as a result of habitat loss from assisting in nest construction, feeding nest- human development and habitat degradation lings, and defending territories (Norris 1958, through fire suppression and logging (With- Thompson 2000), but recent studies of coop- gott and Smith 1998). The species also has erative breeding in this species are limited to exhibited range contraction in some regions two unpublished theses (Slater 1997, Thomp- (e.g., South Florida and Missouri), and With- son 2000) and a study based on 15 territories gott and Smith (1998) noted that nuthatches (Miller and Jones 1999). disappeared from some areas before the en- The Brown-headed Nuthatch is a primary dangered Red-cockaded Woodpecker (Picoi- cavity-nesting species (McComb et al. 1986) des borealis; U.S. Department of Interior 2003) disappeared from those same areas. Ac- cordingly, the Brown-headed Nuthatch has 1 Tall Timbers Research Station, 13093 Henry Bead- el Dr., Tallahassee, FL 32312, USA. been designated a species of management 2 Ecostudies Institute, P. O. Box 703, Mount Vernon, concern in several evaluations (Hunter et al. WA 98273, USA. 1993, Carter et al. 1998, U.S. Department of 3 Corresponding author; e-mail: [email protected] Interior 2002), and the Bahamian subspecies 1 2 THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 119, No. 1, March 2007

(S. p. insularis; Bond 1931) is thought to be glades. Nuthatches disappeared from ENP in highly imperiled (Smith and Smith 1994, the early 1940s apparently as a result of ex- Hayes et al. 2004). tensive logging (Robertson and Kushlan Characteristics of social breeding systems 1984), and data collected here stemmed from have been used to develop management pro- a reintroduction program initiated in 1997. grams for some cooperative breeders that have Most prescribed burns in BCNP and ENP undergone population declines (Walters et al. were conducted during the early wet season 1992, Mumme and Below 1999). Information (May–Jun) at 3 to 5-year return intervals. on cooperative breeding in the Brown-headed Fieldwork and Data Analysis.—Area Nuthatch could have a similar role and also searches were initiated in February to locate broaden our understanding of social breeding territories and find nests. Nests were identified systems (Boland and Cockburn 2002); how- by worn or freshly exposed wood at cavity ever, data regarding the extent and frequency entrances, observing birds excavating cavities, of cooperative breeding, gender of auxiliary or by finding completed nests with eggs or adults, territory establishment and mainte- young. Nest locations were geographically nance, and adult and natal dispersal are gen- referenced using hand-held global positioning erally lacking (Norris 1958, Withgott and systems. Dispersal distances, nest displace- Smith 1998). ments, and territory densities were estimated The objectives of our study were to (1) using ArcView (ESRI 1998) and the straight- quantify and compare demographic parame- line distance between nest locations. ters, population densities, and characteristics Nests were visited every 3–4 days to as- of cooperative breeding between two popula- certain status and gather information on adults tions of Brown-headed Nuthatch in Florida, associated with nests. Nest height at TTRS (2) develop hypotheses for factors influencing generally was Ͻ3 m and nesting status was cooperative breeding in this species, and (3) monitored using step ladders, flash lights, and consider how our information regarding co- dental mirrors. In south Florida, nest height operative breeding and other life history traits averaged Ͼ10 m and status was monitored us- may contribute to population conservation and ing behavioral observations (typically Ͻ30 management. min/visit). A breeding attempt was defined as the presence of eggs or behavioral cues indi- METHODS cating nesting was underway (used for tall Study Areas.—We studied nuthatches at Tall nests). Timbers Research Station (TTRS; 30.66Њ N, Nestlings were banded 13–16 days after 84.22Њ W) in north Florida (2001–present) and hatching at TTRS by removing the front of at two sites in south Florida (1998–2003): Big nesting cavities using a small saw. The cavity Cypress National Preserve (BCNP; 26.03Њ N, face was secured after banding using wood 81.20Њ W) and Everglades National Park putty, staples, and masking tape. A single fed- (ENP; 25.37Њ N, 80.59Њ W). TTRS encom- eral band was affixed to nestlings. All adults passes 1,630 ha and is dominated by upland were color banded. The height of nests in pine habitats consisting primarily of loblolly South Florida precluded banding of young, (Pinus taeda) and shortleaf (P. echina- and data on dispersal for second-year (SY) ta). Dominant trees are Ͼ100 years old, and birds and nestlings stemmed exclusively from prescribed burns are conducted from March to the TTRS population. We compared produc- April at two-year return intervals. Historically, tivity between pairs and cooperative groups upland forests at TTRS were dominated by within populations using (1) the number of longleaf pine (P. palustris), but the original nestlings banded per nest (TTRS) and (2) the forests were cleared for agriculture many de- number of fledglings counted on at least two cades ago (Frost 1993). In south Florida, the visits (south Florida) less than two weeks after BCNP site is associated with an old-growth young left the nest. slash pine (P. elliottii var. densa) forest sur- Most adults were captured using mist nets rounded by a cypress (Taxodium sp.) mosaic. placed near nests, but a few individuals were ENP contained even-aged slash pines inter- lured into mist nets using recorded vocaliza- spersed with hardwood forests and grassy tions of nuthatches or Eastern Screech-owl Cox and Slater • COOPERATIVE BREEDING IN BROWN-HEADED NUTHATCH 3

TABLE 1. Data for color-marked populations of the Brown-headed Nuthatch in Florida.

Study area North Florida South Florida Study length (years) 5 6 Territories monitored 152 195 Territories with helpers (%)a 22.7 Ϯ 11.4 17.3 Ϯ 16.1 Maximum group size 5 4 Territories with nests (%)a 85.2 Ϯ 9.2 83.2 Ϯ 22.4 Adults banded 148 136 Females 66 57 Males 62 57 Unknown 20 22 Nestlings banded 246 SYb in natal territories 8 SYb Dispersed 8 Apparent annual survivalc Females (%)a 66.1 Ϯ 5.3 68.7 Ϯ 13.1 Males (%)a 77.8 Ϯ 4.7 69.3 Ϯ 15.8

a Mean Ϯ SD. b Second Year (SY) individuals banded as nestlings and recaptured the next breeding season. c Estimates obtained from Program MARK (White and Burnham 1999).

(Otus asio). Gender was assigned based on the calizations, copulation, incubation, and dom- presence (female) or absence (male) of a inance (Norris 1958) were used to categorize brood patch on breeding birds, behavioral ob- breeding status either as breeding adult or an servations of color-banded birds (e.g., copu- auxiliary helper; however, individuals de- lation), and presence of a cloacal protuberance scribed as helpers may have been breeders (male; Norris 1958, Pyle 1997). Wing length (Richardson et al. 2001). was used to assign gender for some SY help- Apparent adult survival was estimated with ers captured at TTRS if other traits were Program MARK (White and Burnham 1999) equivocal. Wing length averaged 2.5 mm lon- using observations of color-banded adults dur- ger for males than females among individuals ing subsequent breeding seasons (Feb–Jul). whose gender was assigned using other cri- Data for north and south Florida were ana- teria (t-test ϭϪ9.657, P Ͻ 0.01; all measure- lyzed separately because of differences in ments by JAC). Wing length also appeared to years of study and number of populations vary with age, so gender of some SY birds monitored. Global models that included vari- was assigned only when observed in subse- ation in apparent survival and recapture prob- quent breeding seasons. abilities based on gender, site (south Florida Adults were fitted with three plastic color only), and year were considered initially. bands and an aluminum federal band (two Nested models for north and south Florida bands per leg; federal permits 22446 [JAC] were evaluated using information-theoretic and 22932 [GLS], state permit WB04060a). methods (Anderson et al. 2000). Plastic bands were sealed using acetone. Ex- cept where noted, results were based on color- RESULTS banded individuals and banded nestlings re- Group Size and Frequency; Gender and In- captured as adults. fluence of Helpers.—The largest breeding The size of breeding groups was estimated group contained 5 adults, but most (Ͼ70%) by observing the number of adults engaged in groups with Ͼ2 adults contained 3 adults. The nesting activities (i.e., cavity excavation, nest frequency of territories with Ͼ2 adults ranged building, or providing food for young or in- from 10 to 32% and appeared to be more var- cubating females) on Ͼ2 occasions during the iable in south Florida (CV ϭ 0.93) than at breeding season. Recorded nuthatch vocali- TTRS (CV ϭ 0.50; Table 1). Most helpers zations played near nests were used to solicit were SY males that assisted at the nest of at territorial responses during some visits. Vo- least one parent (n ϭ 8), but we also found 4 THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 119, No. 1, March 2007 males that assisted parents for at least 3 years of the territories monitored each year with (n ϭ 2). A female helper (gender based on considerable variation among study sites and observations in later years) was recorded in years (range ϭ 33–100%). South Florida south Florida and assisted with incubation. study sites exhibited greater variation in the The presence of helpers had no apparent ef- proportion of active territories, and annual fect on the number of young produced. In nesting attempts were Ͻ65% in some years north Florida, we banded an average of 4.35 (Table 1). In south Florida, group size was (SD ϭ 1.11) nestlings in nests tended by Ͼ2 identified in 27 of 42 territories without breed- adults (n ϭ 34) and 4.16 (SD ϭ 1.45) nest- ing attempts. The majority of groups consisted lings in nests tended by pairs (n ϭ 117; t-test of pairs (n ϭ 18), followed by single birds ϭϪ0.534; P ϭ 0.541). In south Florida, ter- (likely males; n ϭ 6), and groups of three in- ritories with helpers (n ϭ 17) averaged 2.94 dividuals (n ϭ 3). In north Florida, territories fledglings per successful nest (SD ϭ 1.19), without observed nesting attempts appeared to while territories consisting of pairs (n ϭ 139) consist of single males (n ϭ 3) or groups of averaged 2.90 fledglings per successful nest males (n ϭ 2 based on color-banded individ- (SD ϭ 1.07; t-test ϭϪ0.147; P ϭ 0.883). uals) that either failed to attract mates or lost However, dead nestlings were found buried in mates before eggs were laid. some nests tended by pairs (n ϭ 5) and sug- The primary sources of nest failures at gested brood reduction occurred. Body mass TTRS were depredation (24%) and cavities differences among nest mates also frequently burned by prescribed fires (21%). In south exceeded 1.5 g (ϳ20% nestling mass in the Florida, most nest failures (37%) appeared to later stages of development). stem from nest depredation based on the cav- We observed six cases where adult males ity damage observed. We also recorded a new provided assistance at neighboring nests fol- egg predator at two nests: broad-headed skink lowing the failure of their nests (i.e., faculta- (Eumeces laticeps). tive helping). Two males provided assistance Pair-bond and Site Fidelity.—Pair bonds at a neighboring nest 3–5 days after they lost extending over several years were common, their nests (and presumably their mates). The and approximately 50% of the territories con- remaining four cases involved breeding males sisted of individuals paired the previous year. that assisted other nests in subsequent breed- Pair bonds became established at almost any ing seasons. time of the year. Two juveniles banded in the Variation in Apparent Survival and Nesting same area in July were paired as breeders the Attempts.—The most parsimonious model se- following breeding season. In contrast, a male lected from Program MARK for south Florida that completed a cavity in mid-March did not included variation in apparent survival by site attract a mate until mid-April. We also ob- (BCNP vs. ENP) but held apparent survival served unpaired males (n ϭ 5) excavating and recapture probabilities (P ϭ 1.0) constant cavities and maintaining territories throughout by gender and year. The most parsimonious the breeding season. model for TTRS incorporated variation in ap- Breeding pairs frequently excavated their parent survival due to gender but held recap- nests within 100 m of nests excavated the pre- ture probabilities (P ϭ 0.93) and survival rates vious year. Some breeding groups (n ϭ 5) ex- within gender constant among years. Apparent cavated nesting cavities in the same snag for annual survival was Ͼ65% for both popula- Ն2 years. Site fidelity also was evident when tions but appeared to be more variable in individuals remained in their territories fol- south Florida (CV Ͼ 0.15; Table 1). Males in lowing the apparent loss of parents (n ϭ 2) or north Florida had the highest apparent surviv- mates (n ϭ 7). Most individuals that retained al (Table 1), while females in north Florida territories successfully attracted new mates in had the lowest apparent survival (Table 1). We subsequent breeding seasons, but more com- also observed new sources of adult mortality: plex scenarios also occurred. In one case, two five females tending nests at TTRS were male siblings that hatched a year apart (the killed either by red ratsnakes (Elaphe guttata) older sibling was a helper when the younger or small mammals. sibling was a nestling) remained in their natal Breeding attempts were observed in Ͼ80% territory following disappearance of their par- Cox and Slater • COOPERATIVE BREEDING IN BROWN-HEADED NUTHATCH 5 ents. These males attracted an unbanded fe- males relocated 586 and 1,020 m, respective- male and initiated a nest in the territory held ly, while a male associated with a four-adult by their parents the following breeding sea- breeding group in 2003 became a breeder in son. Two years later, the younger sibling was a territory 2,080 m away in 2004. There were observed assisting at a neighboring territory no recaptures of SY females at TTRS. while the older sibling had disappeared. Territory Proximity and Dispersal.—Nut- DISCUSSION hatch densities were higher in north Florida The extent of cooperative breeding we ob- than in south Florida. The distances between served (ϳ20%) is similar to that reported in nearest neighboring nests was significantly Georgia (Norris 1958), north Florida (Miller lower at TTRS (mean ϭ 198.5 m, SD ϭ 90.7) and Jones 1999), and Texas (Thompson 2000) than in south Florida (mean ϭ 394.9 m, SD and demonstrates cooperative breeding occurs ϭ 242.8; t-test ϭ 12.86, P Ͻ 0.001). Nearest consistently throughout the range of this spe- neighbor distances at TTRS also generally cies. Although the behavior is widespread, Li- were more consistent from year to year. Av- gon and Burt (2004) noted the potential ben- erage distances at TTRS ranged from 199 to efits and constraints that favor the behavior 216 m annually (CV ϭ 0.04), while average have not been identified. Our data suggest po- distances in south Florida ranged from 370 to tential direct benefits include acquisition of 550 m (CV ϭ 0.169). Nearest neighbor dis- the territory of a parent or neighbor (Wool- tances suggest densities of 0.33 territories/ha fenden and Fitzpatrick 1984, Walters 1990) as at TTRS and 0.08 territories/ha in south Flor- well as assistance provided by offspring that ida. are helped (Hannon et al. 1985). Helpers also Most observed dispersal events spanned may benefit through other means that we did short distances. Seven SY males established not assess, including extra-pair fertilizations, territories or assisted at territories within 300 egg-dumping (Richardson et al. 2001), and in- m of the territory held by their parents (i.e., creased survival or productivity. generally the nearest neighboring nest to the Arnold and Owens (1998) reported high an- natal territory). In two cases, the SY males nual survival was an important factor favoring were nest mates that each attracted unbanded the expression of cooperative breeding in females and initiated nesting attempts within many avian lineages. Our estimate for annual 100 m of their natal nest. In a third case, two survival for the Brown-headed Nuthatch (66– SY siblings were associated with a single fe- 78%) is high for a small (Martin male and initiated a nest within 300 m of their 1995) and markedly higher than the estimate natal nest. In a fourth case, a SY male was of 54% reported by Norris (1958). We also captured assisting at a territory adjacent to his found gender-based differences in survival in natal territory. The territory was held by a north Florida and believe this influenced co- male banded the previous breeding season, operative breeding. Skutch (1961) originally while the father of the SY male was engaged suggested a shortage of female nuthatches in a nesting attempt Ͻ150 m away and as- might constrain breeding opportunities for sisted by a nest mate of the SY male at the males (based on sex ratios reported in Norris neighboring nest. Two males also established 1958), and we found additional support for territories next to territories of the breeding this hypothesis in the discovery (n ϭ 5) of adults they assisted during a previous breed- breeding females consumed by ratsnakes and ing season. small mammals in nesting cavities. Four SY males were recaptured Ն2 terri- Lower survival among females may be re- tories from natal territories. Dispersal aver- lated to the strong nest attentiveness exhibited aged 1,358 m for males dispersing Ն2 terri- during incubation and brooding coupled with tories. The limited data primarily demonstrate the low height (Ͻ3 m) of cavities used at that some males disperse and attempt to breed TTRS (and elsewhere; McNair 1984). Fe- (successfully [n ϭ 2]) in their first year, while males rarely flushed when nests were inspect- others stay and help. Dispersal of older indi- ed at TTRS, and we suspect this behavior re- viduals (after their SY) Ն2 territories also oc- duced egg depredation (Dornak et al. 2004) curred infrequently (n ϭ 3). Two breeding fe- by small lizards or nest usurpation by cavity 6 THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 119, No. 1, March 2007 competitors (e.g., Carolina Chickadee, Poecile ritories were held by siblings or parent-off- carolinensis). This behavior leads to higher spring combinations. Helpers also may lighten predation risks for females (Martin and Li feeding responsibilities for females and enable 1992), especially later during the breeding them to initiate second clutches (Thompson season when warmer ambient temperatures 2000). Helpers also may serve as sentinels lead to increased snake activity (Neal et al. (McGowan and Woolfenden 1989) and de- 1993, Weatherhead and Blouin-Demers 2004). crease female (and in most cases maternal) In contrast, the absence of gender-based susceptibility to predators. survival differences in south Florida suggests Cooperative breeding in the Brown-headed factors such as food resources (Koenig and Nuthatch is similar to Pygmy Nuthatch (S. Stacey 1990) or habitat features (Walters pygmae) behavior and suggests this trait was 1990) may constrain breeding opportunities in present in a shared ancestor (Ligon and Burt this region. This hypothesis is consistent with 2004). Helping behavior is observed in about our data suggesting that habitat quality is low- 15–30% of the annual territories of both spe- er in south Florida (e.g., lower territory den- cies (Norris 1958, Miller and Jones 1999, Kin- sities, greater variation in annual breeding ef- gery and Ghalambor 2001) and less frequently fort, and greater variation in adult survival; reaches frequencies as high as 40% (Slater Table 1). Nest productivity also appeared to 1997, Miller and Jones 1999, Kingery and be lower in south Florida than at TTRS and Ghalambor 2001). Facultative helping occurs elsewhere (Morris 1982, Miller and Jones infrequently (Sydeman 1991) and, while 1999, Thompson 2000). McNair (1984) also breeding groups may include up to five adults, noted reduced clutch sizes for nuthatches in they more typically contain either two or three south Florida and suggested the reductions adults (Sydeman et al. 1988). Cooperative be- stemmed from environmental factors. havior in the Pygmy Nuthatch has been linked Nuthatches in south Florida select nest ter- both to skewed sex ratios (Norris 1958, ritories with a greater proportion of large Skutch 1961) and environmental features (Sy- pines (Slater 1997), and the density and di- deman et al. 1988). versity of large pine trees might affect food The life-history characteristics we docu- resources and habitat quality (Koenig and mented in association with cooperative breed- Haydock 1999). Large pines produce propor- ing suggest that management of small, isolat- tionally more seeds than smaller pines (W. J. ed populations of Brown-headed Nuthatches Platt, pers. comm.), and nuthatches cache and deserves special attention. This species is rel- rely heavily upon pine seeds during the winter (Yaukey 1995). We did not measure pine seed atively sedentary and appears to disperse short production, but we suspect it is more variable distances. Accordingly, it is unlikely to re-col- in south Florida where only one species of onize isolated areas should populations dis- pine occurs (slash pine). TTRS supports four appear (Walters et al. 2004). This phenome- species, including two consistent seed-produc- non has already occurred in south Florida ers (loblolly and short-leaf pines; Cain and (Robertson and Kushlan 1984) and other areas Shelton 2001). Large pines also have greater where the species’ range has contracted. Man- surface area, providing more foraging space. agement should focus on retention of mature, Helpers appeared to be closely related to seed-bearing pine trees, particularly in situa- breeders, and alloparental care may include tions where pine basal area is low and only indirect benefits (Brown 1978). Even for sit- 1–2 species of pines exist. Retaining sufficient uations where individuals provided assistance snag resources also should alleviate competi- at neighboring nests, the short dispersal dis- tion for nesting sites (McComb et al. 1986) tances we recorded suggested neighbors often and reduce nest depredation (Li and Martin were closely related. Three adjacent territories 1991). Timing of prescribed burns also de- monitored in 2004 consisted of (1) a father, serves attention where small, isolated popu- (2) a son born in 2002, and (3) a son born in lations exist. Frequent prescribed burning is 2003. In addition, the father was assisted in essential for maintaining suitable habitat con- 2004 by a male offspring born in 2003. We ditions (Engstrom et al. 1984), but burns con- observed six other cases where adjacent ter- ducted during the nesting season destroy nests Cox and Slater • COOPERATIVE BREEDING IN BROWN-HEADED NUTHATCH 7 and shift re-nesting to periods with warmer of the Brown-headed Nuthatch (Sitta pusilla)in ambient temperatures. eastern Texas. Southeastern Naturalist 3:683–694. Our study suggests that cooperative breed- EGAN,E.S.AND M. C. BRITTINGHAM. 1994. Winter survival rates of a southern population of Black- ing in the Brown-headed Nuthatch is a fluid capped Chickadee. Wilson Bulletin 106:514–521. behavior that should be amenable to experi- ENGSTROM, R. T., R. L. CRAWFORD, AND W. W. B AKER. mental manipulation. For example, female 1984. Breeding populations in relation to survival in north Florida may be improved by changing forest structure following fire exclusion: protecting nesting cavities from predators a 15-year study. Wilson Bulletin 96:437–450. (e.g., Withgott et al. 1995). This treatment ESRI, INC. 1998. ArcView. Version 3.2. Earth Systems Research Institute, Inc., Redlands, California, should lead to fewer breeding groups consist- Ͼ USA. ing of 2 adults (unless the habitat becomes FROST, C. 1993. Four centuries of changing landscape saturated). Supplemental food (e.g., Egan and patterns in the longleaf pine ecosystem. Pages 17– Brittingham 1994, Yaukey 1995) could be 43 in The longleaf pine ecosystem: ecology, res- provided in south Florida to learn if group size toration, and management (S. M. Hermann, Edi- increases in territories with better food re- tor). Proceedings of the Tall Timbers Fire Ecology sources (Koenig and Stacey 1990). Conference 18. Tall Timbers Research Station, Tallahassee, Florida, USA. ACKNOWLEDGMENTS HANNON, S. J., R. L. MUMME,W.D.KOENIG, AND F. A. PITELKA. 1985. Replacement of breeders and We thank B. J. Hartman, R. K. Henderson, C. A. within-group conflict in the cooperatively breed- Jones, and S. R. Jones for assistance in the field, and ing Acorn Woodpecker. Behavioral Ecology and R. W. Snow for logistical and technical assistance for Sociobiology 17:303–312. work in ENP. R. T. Engstrom, J. A. Jackson, R. T. HAYES,W.K.,R.X.BARRY,Z.MCKENZIE, AND P. B AR- Kimball, R. A. Norris, K. G. Smith, and two anony- RY. 2004. Grand Bahama’s Brown-headed Nut- mous reviewers provided helpful comments on earlier hatch: a distinct and endangered species. Bahamas drafts. Work at TTRS was supported by the Wildlife Journal of Science 12:21–28. Research Endowment, while research at south Florida HUNTER, W. C., D. N. PASHLEY, AND RE.F.ESCANO. was supported by the National Park Service’s Critical 1993. Neotropical migratory landbird species and Ecosystem Science Initiative. their habitats of special concern within the south- east region. Pages 59–171 in Status and manage- LITERATURE CITED ment of neotropical migratory birds (D. M. Finch ANDERSON,D.R.,K.P.BURNHAM, AND W. L. THOMP- and P. W. 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