Artificial Nests Identify Possible Nest Predators of Eastern Wild Turkeys

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1 SOUTHEASTERN Southeastern Naturalist NATURALIST Vol. 13(1): , No. 1 Artificial Nests Identify Possible Nest Predators of Eastern Wild Turkeys Haemish I.A.S. Melville 1,2,*, Warren C. Conway 3, Michael L. Morrison 1, Christopher E. Comer 3, and Jason B. Hardin 4 Abstract - Poor nest survival is a critical limiting factor in the recruitment of wild birds. Nest predation is often cited as one of the main causes of nest failure, especially for ground-nesting species. We monitored artificial Meleagris gallopavo silvestris (Eastern Wild Turkey) nests, using time-lapse and motion-sensitive trail cameras to determine which predators were likely to be responsible for preying on Wild Turkey nests in the Pineywoods of East Texas. Sixty-one percent of all artificial nests were preyed upon. Corvus brachyrhynchos (American Crow) preyed on 48% of artificial nests and Procyon lotor (Raccoon) preyed on 35%. There was a seasonal increase in the number of artificial nests preyed upon from spring to summer. Mammalian mesopredators, Raccoon and Didelphis virginiana (Opossum), were primarily responsible for this increase, suggesting an increase in search effort by mesopredators that coincided with increased dietary diversity in a period of reduced prey resources. Predators other than mesopredators American Crows, Picoides sp. (woodpeckers), Dasypus novemcinctus (Nine-banded Armadillo), and snakes were responsible for 53% of all predation on the artificial Wild Turkey nests, with American Crows being the most important of these. After nest deployment, American Crows located and preyed on artificial nests more quickly than other nest predators. We suggest video monitoring of natural Eastern Wild Turkey nests to confirm the identity of nest predators. Introduction The degree to which predators affect their prey resources is central to the study of ecology (Begon et al. 2006). It is of overriding importance when considering the control of abundant prey species, the conservation of endangered prey species (Macdonald et al. 1999), and prey species of ecological, economic, or recreational importance. The effects of predation can make the difference between persistence and local extinction of rare prey species (Caughley and Sinclair 1994, Macdonald et al. 1999). Predation may interact with other causes of mortality, and the additive effect may cause the collapse of prey populations (Macdonald et al. 1999). Nesting by Meleagris gallopavo silvestris Vieillot (Eastern Wild Turkey) is confined to the spring months (late March to late June; Healy 1992, Isabelle 2010). Poor nest survival is one of the primary limitations to the successful recruitment of bird species (Dreibelbis et al. 2008). Predation is often cited as the main cause of nest fatality in avian species (Martin 1993a; Mezquida 2001, 2003; Ricklefs 1969; 1 Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, TX Current address - Number 8 25 th Street, Zakher, Al Ain, United Arab Emirates. 3 Arthur Temple College of Forestry and Agriculture, Stephen F. Austin State University, Nacogdoches, TX Texas Parks and Wildlife Department, Oakwood, TX * Corresponding author - haemish.melville@gmail.com. Manuscript Editor: Roger D. Applegate 80

2 Rotenberry 1989), and ground-nesting birds are particularly vulnerable to mammalian and avian predation (Fletcher et al. 2010, Marcstrom et al. 1988, Newton 1993). Meleagris gallopavo L. (Wild Turkey) is a ground-nesting species of which hens, nests, and young poults are especially vulnerable to predation (Glidden 1975, Miller and Leopold 1992, Speake 1980). Wild Turkeys also have a long incubation period, approximately 26 days (Healy 1992, Williams et al. 1971), which extends its period of vulnerability. Eastern Wild Turkeys are not known to display any defensive behaviors against mammalian predators; rather, they have evolved adaptations including morphological and behavioral crypsis, large size, and exceptional eyesight to counter predator pressure (Leopold and Chamberlain 2002). In the US, Wild Turkeys were on the brink of extinction through habitat loss and hunting (Lopez et al. 2000, Kennamer et al. 1992). Attempts to restore the Wild Turkey have generally been successful nationwide (Kennamer et al. 1992), but this has not been the case in the Pineywoods of East Texas, despite the translocation of over 7000 Eastern Wild Turkeys into the state since 1979 (Boyd and Oglesby 1975, Isabelle 2010, Seidel 2010). Despite reintroduced turkeys achieving nest-success rates comparable to those in areas where Wild Turkeys have been successfully reintroduced (Isabelle 2010, Vangilder 1992), no self-sustaining population has been established. Predation rates differ for artificial and natural nests. There is no conclusive evidence that artificial nests and natural nests show a consistent trend or relationship to one another in terms of predation rate (Mezquida 2003). Although artificial nests are useful to identify potential nest predators (Wilson et al. 1998), they can attract predators that would not usually locate or depredate live nests (Dreibelblis et al. 2011, Willebrand and Marcstrom 1988). Differential egg characteristics have been demonstrated to affect predation rates (Lindell 2000, Major and Kendal 1996). Nest characteristics may vary between real and artificial nests; for example, artificial nests are often located in habitats that birds would not select for nesting. Generally the predation rate on artificial nests has been found to be greater than on real nests (MacIvor et al. 1990, Major and Kendal 1996, Roper 1992, Salonen and Penttinen 1988). Where the study species is rare, it is often not possible to find enough real nests to assess factors that influence nest predation (Reitsma et al. 1990). In addition, when the influence of monitoring live nests might compromise the success of nests, it is not ethical to monitor real nests. Consequently, we concluded that, despite their limitations, the use of artificial nests was the best means to investigate the variables that might influence predation on Eastern Wild Turkey nests in the Pineywoods. With the above provisos in mind, we developed an experiment to determine which predators would prey on artificial Wild Turkey nests, whether nest sites selected by Wild Turkeys were less susceptible to predation than sites in random locations, whether there was differential seasonal predation on artificial nests, and whether the presence of a proxy for the Wild Turkey hen at the nest would influence predation on the artificial nest. 81

3 Study Area We conducted this study from January 2009 to September 2011 at two sites in the heart of the Pineywoods ecoregion in Nacogdoches and Angelina counties of East Texas: study site 1 (UTM coordinates: N, W; 1360 ha) and study site 2 (372302N, W; 5000 ha). We selected these properties because they represent typical Wild Turkey habitat in East Texas, they both support stable populations of Eastern Wild Turkeys, and several translocations have been attempted in the vicinity of these properties (Isabelle 2010). The Pineywoods occur in the western Gulf coastal region and extend through east Texas, northwestern Louisiana, and southwestern Arkansas. Little of the original Pinus palustris Mill. (Longleaf Pine) and Pinus echinata Mill. (Shortleaf Pine) forests remain. They have been largely replaced by even-aged Pinus taeda L. (Loblolly Pine) plantations. Much of the natural vegetation of the Pineywoods has been altered due to the planting of pine and the exclusion of fire (Omernik et al. 2008). In addition, 63% of the region s land is in private ownership, with much of this in relatively small parcels of ha. One consequence of small parcel size is forest fragmentation (US Forest Service 2002), which has substantially altered the habitat historically used by Wild Turkeys. The mean annual rainfall in the Pineywoods is 1192 mm, with a monthly mean that varies between a low of 55 mm in July and a maximum of mm in May. The mean annual minimum temperature is 12.8 C, and the mean annual maximum temperature 25.5 C. The mean maximum temperature in the summer is 35 C (Sivanpillai 2005). During our study, the mean annual temperature was 19.4 C, the minimum temperature recorded was -5.3 C, and the maximum temperature was 38 C (NOAA 2012). The mean annual rainfall during our study was 1015 mm, with the greatest rainfall occurring in 2009 (1243 mm) and the lowest in 2011 (832 mm) (NOAA 2012). Methods We implemented a manipulative experiment using artificial Wild Turkey nests and motion-sensing, time-lapse photography. We developed an experimental protocol to minimize most problems associated with artificial nest studies. This approach entailed leaving minimal human scent (by wearing latex gloves while handling any equipment and eggs, and by ensuring that field workers wore rubber boots and latex gloves while setting up artificial nests and positioning cameras), not revisiting the artificial nest sites during the experiment, using a proxy for the presence of a Wild Turkey female, adding real Wild Turkey feathers to the artificial nest as scent cues, and using nest-sites that were known to have been used by Wild Turkeys in the past (Isabelle 2010). Because the Gallus domesticus (L.) (Domestic Chicken) eggs we used are smaller than Wild Turkey eggs, they did not limit predators ability to consume the eggs. We avoided deploying the artificial nests in a systematic pattern; rather, within each study site, we located the nests in locations used previously by Wild Turkeys (see Isabelle 2010). We conducted this experiment seasonally from spring 2009 to fall Spring and summer coincided with the nesting season for Eastern Wild Turkeys in the 82

4 Pineywoods (Isabelle 2010). This seasonal approach allowed us to assess whether mesopredators searched for artificial Wild Turkey nests seasonally (e.g., greater effort during spring when Wild Turkey nests are naturally available), or whether they encountered the artificial Wild Turkey nests randomly as a result of their movements in their home-ranges. We defined the seasons as: spring (21 March 20 June), summer (21 June 20 September), fall (21 September 20 December), and winter (21 December 20 March). Each year, we placed artificial nests in 5 randomly selected locations at each study site known to have been used by a Wild Turkey the year before (Isabelle 2010). Wild Turkey nests consist of shallow depressions formed by the hen and lined with leaves and feathers (Healy 1992). To create the artificial nests, we formed 20-cm-diameter depressions in the ground with our hands and positioned leaves and Wild Turkey feathers in these depressions to simulate the appearance of natural nests. Using GIS, we randomly selected another 5 locations at each study site for the placement of artificial nests. We navigated to each randomly selected location, and set-up the artificial nest in the nearest position that approximated a typical Wild Turkey nest setting (Isabelle 2010). We changed locations used for artificial nests each year to facilitate comparisons between predators that preyed on artificial Wild Turkey nests located in known nesting areas with artificial Wild Turkey nests positioned outside documented nesting areas. After one of our cameras failed in spring 2010, we monitored 19 artificial nests for the remainder of the study. We deployed the artificial nests and then left them unchecked for 14 days (half the Wild Turkey incubation period; Campo et al. 1989, Isabelle 2010, Ransom et al. 1987). We did not leave the eggs in place for >14 days because if the eggs rotted, their odor would change the olfactory signature. We did not replace eggs during the 14-d period because our visit might have compromised the nests by leaving additional human olfactory and visual cues for predators. We positioned decoys (Feather Flex 3-position Hen Turkey Decoys) representing sitting Wild Turkey females on 5 of the artificial nests located at the documented Wild Turkey nesting sites and on 5 of the artificial nests that we had placed at random locations. We baited the artificial nests with 12 unwashed Domestic Chicken eggs (Hernandez et al. 1997b, Yahner and Mahan 1996). Using binding wire, we positioned the time-lapse/motion-detecting cameras (Reconyx RM45) on tree trunks within 5 m of the next bowls, and then programmed them to be triggered once every 5 minutes or by movement near the artificial nest bowl. Based on field evidence from the cameras, we calculated the percentage of nest-predation events that involved total predations and partial predations relative to species of predator and relative to type of predator (mesopredator/other type of predator). Analyses We used logistic regression including all variables (year, season, study site, nest site, and presence of a decoy) to investigate the factors that influenced the likelihood of predation on artificial nests (Vander Haegen and Degraaf 1996, Vander Haegen et al. 2002). We also used logistic regression including all variables (year, 83

5 season, study site, nest site, the presence of a decoy, and time to predation) to investigate relationships between the likelihood of artificial Wild Turkey nests being preyed on by mesopredators rather than by other predators. We used likelihood ratio and Hosmer-Lemeshow tests to determine the suitability of the models and odds ratios (OR) to identify the influence of main effects (Vander Haegen and Degraaf 1996, Yahner and Wright 1985). We used OR to reflect the influence of each of the significant variables on the likelihood of artificial nest predation. We recorded the time to predation (from the time of nest deployment) for each artificial nest. We used fixed-effects analysis of variance (ANOVA; Zar 1999) to determine whether the time to predation of artificial nests varied relative to type of predator, year, season, study site, location on historic nest site, and presence of Wild Turkey decoy. Results We monitored 20 artificial Eastern Wild Turkey nests (artificial nests) seasonally from spring 2009 to spring 2010, and 19 artificial nests from summer 2010 to summer Confirmed species that depredated artificial Wild turkey nests were: Corvus brachyrhynchos Brehm (American Crow), Procyon lotor L. (Raccoon), Didelphis virginiana Kerr (Virginia Opossum), Urocyon cinereoargenteus Schreber (Gray Fox), Dasypus novemcinctus L. (Nine-banded Armadillo), Lynx rufus Schreber (Bobcat), Canis latrans Say (Coyote), Picoides sp. (woodpeckers), and unidentified snakes as well as other unknown nest predators (Table 1). For mesopredators, the mean times to predation on artificial Wild Turkey nests were 6.5 days (n = 41, SE = 0.72) for Raccoons, and 9.0 days (n = 10, SE = 1.65) for Opossums; American Crows discovered and preyed on artificial Wild Turkey nests more quickly (mean = 4.3 days, n = 58, SE = 0.56). Approximately 61% (118 of 194) of all artificial nests monitored (regardless of season) were depredated. On study site 1, 53% of artificial nests were depredated, Table 1. Predators responsible for preying on artificial Wild Turkey nests, in the Pineywoods of East Texas from spring 2009 to fall Seasonal predation Entire study Winter Spring Summer Fall Predator n % n % n % n % n % Armadillo Bobcat Coyote Crow Gray Fox Oppossum Raccoon Snake Woodpecker Unknown Total

6 compared to 69% on study site 2. In 2011, 85% of all artificial nests were depredated, compared with 56.7% in 2009 and 62.5% in % of artificial nests deployed on historic Wild Turkey nest sites were depredated compared, to 54% of randomly located artificial nests. We found that 86.3% of artificial nests were depredated in summer, compared with 55% in fall, 54.3% in spring, and 69% in winter. Study site (study site 1: Z = -2.69, df = 1, P = 0.007), year (2011: Z = 4.19, df = 1, P < 0.001), nest site (Z = 2.09, df = 1, P = 0.036), and season (summer: Z = 3.30, df = 1, P < 0.001) influenced whether artificial nests were depredated. Using the Hosmer-Lemeshow goodness-of-fit test, we failed to detect a significant difference between the full model and the null model (χ 2 = 7.95, df = 8, P = 0.44), indicating that the model fit the data. We found further support for the plausibility of the model using a likelihood ratio test (log likelihood = , df = 9, P < 0.001). The OR indicated that study site 1, the year 2011, real nest sites, and summer season were variables that increased the likelihood of artificial nests being depredated. Between spring 2009 and fall 2011, 118 artificial nests were depredated, 53.4% (n = 63) by species other than mesopredators (Table 2). The variables year (2010: Z = -3.95, df = 1, P < 0.001), year (2011: Z = -2.76, df = 1, P = 0.006), nest site (Z = 2.31, df = 1, P = 0.02), and time to predation (Z = 3.20, df = 1, P = 0.001) influenced whether an artificial nest was depredated by a mesopredator or another type of predator. Using a Hosmer-Lemeshow test, there was no difference between the full model and the null model (χ 2 = 9.35, df = 8, P = 0.31), which indicated that the model fit the data. We found further evidence for the fit of the model using a likelihood ratio test (log likelihood = , df = 9, P < 0.001). The mean time between deployment of an artificial nest and a mesopredator preying on the nest was 6.8 days (n = 57, SE = 0.63 days), whereas the mean time for other predators was 4.6 days (n = 60, SE = 0.56 days), mostly because of the relatively prompt depredation of nests by American Crows. The mean time to predation in 2009 was 6.1 days (n = 29, SE = 0.92), in 2010 it was 7.0 days (n = 41, SE = 0.75), and in 2011 it was 4.2 days (n = 47, SE = 0.57). The relationship between time to predation and year (F = 8.14, df = 2, P < 0.001) indicated that differences existed in time to predation between 2009 and 2010 Table 2. Contributions of mesopredators to predations on artificial artificial Wild Turkey nests in the Pineywoods of East Texas from spring 2009 to fall Predation Type of predator Time period n % Mesopredator Other Mesopredator Other Mesopredator Other Mesopredator Other

7 (Tukey HSD difference = 3.71, P = 0.002), and between 2010 and 2011(Tukey HSD = -2.92, P = 0.006). Time to predation for mesopredators varied from other nest predators (F = 6.4, df = 1, P = 0.013). The mean time to predation varied between study sites (F = df = 1, P = 0.006; study site 1: 7.0 days, n = 53, SE = 0.66; study site 2: 4.5 days, n = 64, SE = 0.52). The variables season (F = 0.141, df = 3, P = 0.93), nest site (F = 0.203, df = 1, P = 0.65), and the presence of a decoy (F = 2.58, df = 1, P = 0.11) had no influence on time to predation. Artificial nests were completely depredated during the first visit by a nest predator in 31% of cases, there was secondary predation in 68% of cases, and in one instance five of the eggs were eaten and the rest were still in place and intact when we removed the artificial nest. Only 5% of secondary predations were performed by species other than those that had initially preyed upon the artificial nests. In three instances, mesopredators (Raccoon = 2, Gray Fox = 1) were the secondary predator on artificial nests that Crows had initially depredated, and in one instance an American Crow was secondary predator at an artificial nest depredated by a snake. There was little delay between primary and secondary predations (mean = 0.96 days, n = 80, SE = 0.19). The mean times to secondary predation were 0.84 days (n = 28, SE = 0.25) for Raccoons, 0.68 days (n = 10, SE = 0.1) for Opossums, and 0.59 days (n = 33, SE = 0.16) for American Crows. In 76% (n = 72) of predations on artificial nests by mesopredators, there were instances of secondary predation; 60% (n = 38) of primary predation events by other predators were followed by secondary predation. On 70% (n = 28) of the occasions that Raccoons preyed on artificial nests, nests were not completely depredated in the first predation bout, while 63% (n = 36) of artificial nest predations by Crows were followed by secondary predations. Discussion The degree to which American Crows preyed on artificial nests was greater in our study within the Pineywoods than in other studies (Baker 1978, Davis 1959, Hernandez et al. 1997a, Miller and Leopold 1992, Pharris and Goetz 1980). From January 2009 September 2011, the incidence of predation on artificial nests by American Crows increased. This finding might be attributable to natural variability in the degree to which various nest predators prey on nests (Bayne et al. 1997, Buler and Hamilton 2000, Mezquida 2003). Although we changed the location of artificial nest sites on an annual basis, we used the same study sites each season throughout the year, which may have provided sufficient exposure for resident American Crows to cue in on our placement of the artificial nests (Wilson et al. 1998). Corvids, such as American Crows, primarily use visual cues to locate nests (Santisteban et al. 2002). The presence of Wild Turkey hens on live nests camouflages eggs from avian predators. Despite this, corvids have been recorded preying on active Wild Turkey nests (Dreibelbis et al. 2008). Wild Turkeys cover their newly laid eggs prior to the onset of incubation, but once incubation commences, hens do not camouflage the eggs when they leave the nest for short periods to forage (Healy 1992). We made no attempt to obscure the eggs within the nest bowls, which may have made the eggs more obvious targets for visual predators. The high visibility 86

8 of the eggs within the nest bowls and the concomitant high incidence of American Crows depredating artificial nests might be an important factor that differentiates between predators of artificial Wild Turkey nests and those of real nests, especially because Wild Turkeys have been observed defending their nests from crows (B. Collier, Institute for Renewable Natural Resources, Texas A&M University, College Station, TX, pers. comm.). The relatively short time that it took American Crows to detect artificial nests is probably also a consequence of the easily visible eggs in artificial nests when no female Turkey was present. The diversity of mammalian species that preyed on artificial Wild Turkey nests was similar to that reported in other US studies (Miller and Leopold 1992), and more specifically those conducted in the Southeast (Lovell et al. 1995). Raccoons and Opossums were the most frequent mammalian mesopredators on artificial Wild Turkey nests in our study. Although we recorded Bobcats and Coyotes at artificial nests, the instances of predation on artificial nests by these mesopredators was limited to one incident each. Many studies have reported that mammalian mesopredators kill adult Wild Turkeys, especially incubating hens (Glidden 1975, Miller and Leopold 1992, Speake 1980). Yet, we found no evidence of Wild Turkey feathers, bones, or other remains in Bobcat, Coyote or Raccoon scats found on these study sites during a concurrent study (Melville 2012). However, there was an increase in the incidence of predation, specifically by mesopredators, on our study nests in summer, a pattern that has been attributed to decreases in availability of small mammalian prey (Melville 2012), and the consequent necessity to increase the search rate for preferred prey by nest predators during summer (Hoi and Winkler 1994, Knick 1990, Melville 2012, Schmidt 2008). Wild Turkeys select nest sites that allow them to conceal themselves from predators (Holbrook et al. 1985, 1987; Isabelle 2010; Lazarus and Porter 1985; Martin 1993b; Porter 1992; Schmutz et al. 1989). We found that during spring, the rate of predation on historic nest sites was similar to that for all artificial nest sites. However, when we assessed the degree of predation over all seasons, the level to which historic nest sites were depredated was greater than for the rates on randomly located sites. This finding was probably due to the phenology of the plants in the region: a dense, shrubby understory develops during spring (Chenault 1940, Halls 1973). The dense understory served as cover for the artificial nests, and as the seasons proceeded, herbaceous plants senesced and provided less nesting cover than during spring. We hypothesized that the presence of a Wild Turkey decoy as a proxy for the presence of a Wild Turkey hen would reduce the incidence of predation on artificial nests because it increased the level of camouflage for the eggs to protect them from both avian and terrestrial predators. In addition, the physical presence of the decoy was unfamiliar to predators and might have caused them to be more cautious when approaching the artificial nests. This was not the case. Thus, differences in predation rates between artificial nests and real nests appears to be the consequence of a combination of cues and not merely the physical presence of a proxy for a hen at the nest site. 87

9 It was clear from our study that predation on artificial nests was extensive on both study sites, and our results indicated that nest predation may contribute to reduced productivity of Eastern Wild Turkeys in the Pineywoods of East Texas. It is necessary to monitor live Wild Turkey nests to confirm which predators are responsible for preying on them. To this end, we recommend an ongoing program to monitor female Eastern Wild Turkeys via radio transmitters in conjunction with future translocations to help researchers to locate nests and monitor them with nest cameras. If no future translocations are planned, attempts should be made to capture extant female Wild Turkeys, fit them with radio transmitters, and monitor their nests to determine which predator species are responsible for preying on the nests. Our data could then be compared with the findings from nest-monitoring studies to determine if our results mirror real-nest predation events. Acknowledgments This project was funded by federal excise taxes on sport hunting arms and ammunition, Grant W132R, with the Texas Parks and Wildlife Department. Support for this research was also provided by Texas A&M University (Department of Wildlife and Fisheries Science), and Stephen F. Austin State University (The Arthur Temple College of Forestry and Agriculture). We thank all the researchers and research technicians including A. Wadyko, J. van Woert, T. Yurick, J. Deatherage, J.Rogers, J. Isabelle, A. Davis, S. Seidel, and J. Wisnant. Literature Cited Baker, B.W Ecological factors affecting Wild Turkey nest predation on south Texas rangelands. Proceedings of the Annual Conference of the Southeastern Association of Fish and Wildlife Agencies 32: Bayne, E.M., K.A. Hobson, and P. Fargey Predation on artificial nests in relation to forest type: Contrasting the use of quail and plasticine eggs. Ecography 20: Begon, M., C.R. Townsend, and J.L. Harper Ecology: From individuals to ecosystems. Wiley-Blackwell, Boston, MA. 752 pp. Boyd, C., and R. Oglesby Status of Wild Turkey restoration in east Texas. Proceedings of the National Wild Turkey Symposium 3: Buler, J.J., and R.B. Hamilton Predation of natural and artificial nests in a southern pine forest. The Auk 117: Campo, J.J., C.R. Hopkins, and W.G. Swank Nest habitat use by Eastern Wild Turkeys in Eastern Texas. Proceedings of the Annual Conference of the Southeastern Association os Fish and Wildlife Agencies 43: Caughley, G., and A.R.E. Sinclair Wildlife Ecology and Management. Wiley-Blackwell, Boston, MA. 334 pp. Chenault, T.P The phenology of some Bob-white food and cover plants in Brazos County, Texas. The Journal of Wildlife Management 4(4): Davis, J.R A preliminary progress report on nest predation as a limiting factor in Wild Turkey populations. Proceedings of the National Wild Turkey Management Symposium 1: Dreibelbis, J.Z., K.B. Melton, R. Aguirre, B.A. Collier, J. Hardin, N.J. Silvy, and M.J. Peterson Predation of Rio Grande Wild Turkey nests on the Edwards Plateau, Texas. The Wilson Journal of Ornithology 120(4):

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12 Santisteban, L., K.E. Sieving, and M.L. Avery Use of sensory cues by Fish Crows, Corvus ossifragus, preying on artificial bird nests. Journal of Avian Biology 33(3): Seidel, S Genetic structure and diversity of the Eastern Wild Turkey (Meleagris gallopavo silverstis) in East Texas. M.Sc. Thesis. Stephen F. Austin State University, Nacogdoches, TX. 162 pp. Schmidt, K Behavioural and spatial adaptation of the Eurasian Lynx to a decline in prey availability. Acta Theriologica 53(1):1 16. Schmutz, J.A., C.E. Braun, and W.F. Andelt Nest habitat use of Rio Grande Wild Turkeys. The Wilson Bulletin 101(4): Sivanpillai, R., C.T. Smith, R. Srinivasan, M.G. Messina, and X.B. Wu Estimating regional forest cover in east Texas using enhanced thematic mapper (ETM+) data. Forest Ecology and Management 218(1 3): Speake, D.W Predation of Wild Turkeys in Alabama. Proceedings of the National Wild Turkey Symposium 4: US Forest Service Forest inventory and analysis for Texas Available online at Accessed 20 August Vander Haegen, W.M., and R.M. Degraaf Predation on artificial nests in forested riparian buffer strips. The Journal of Wildlife Management 60(3): Vander Haegen, W.M., M.A. Schroeder, and R.M. DeGraaf Predation on real and artificial nests in shrubsteppe landscapes fragmented by agriculture. The Condor 104(3): Vangilder, L.D Population Dynamics. Pp , In J.G. Dickson (Ed.). The Wild Turkey: Biology and Management. Stackpole Books, Harrisburg, PA. 463 pp. Willebrand, T., and V. Marcstrom On the danger of using dummy nests to study predation. Auk 105: Williams, L., Jr., D.H. Austin, T.E. Peoples, and R.W. Phillips Laying data and nesting behavior of Wild Turkeys. Proceedings of the Annual Conference of the Southeastern Association of Game and Fish Commissioners 25: Wilson, G.R., M.C. Brittingham, and L.J. Goodrich How well do artificial nests estimate success of real nests? Condor 100: Yahner, R.H., and C.G. Mahan Effects of egg type on depredation of artificial ground nests. The Wilson Bulletin 105(1): Yahner, R.H., and A.L. Wright Depredation on artificial ground nests: Effects of edge and plot age. The Journal of Wildlife Management 49(2): Zar, J.H Biostatistical Analysis (Fourth Edition). Pearson Education, Inc., Panscheel Park, New Delhi, India. 929 pp. 91