Reproductive ecology of Eastern wild turkey hens in Sussex County Delaware

Date
2012
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University of Delaware
Abstract
With the increase popularity in turkey hunting in the State of Delaware and the increase in turkey numbers since 1984, the state of Delaware and the university of Delaware started a project to investigate the reproduction success of Eastern wild turkey hens (Melagris gallopavo silvestris). I captured 106 turkeys using rocket nets and placed backpack transmitters on 76 hens in December 2009-March 2010 and December 2010-March 2011. I classified each bird as adult or juvenile, marked them with unique bands and placed transmitters on hens weighing >3.4 kg (>7.5lbs). To estimate survival, I took locations from fixed ground telemetry stations 3-7 times a week. The estimated survival rate of adult hens in 2010 was 0.47(SE=0.09), which was 0.21 less than the 2011 survival rate of 0.68 (SE=0.07; X 2 1 = 2.82, P = 0.093). Predation accounted for 87.1% (n = 27) of the moralities with foxes being attributed to most predation events (85.2%, n =23). Most mortalities (61.3%, n=19) occurred during the nesting season (15 April-15 June). The variation in annual survival justifies the need for continued monitoring of this population. Nest success has been found to be an important factor in overall population success. Nesting habitat variables and landscape variables have been studied before with a wide range of what hens select for a nest and what habitat variables effect nest success. I placed 76 transmitters on hens, and used telemetry to determine nesting times and locations from fixed ground stations. I walked in on nest locations to find an exact position, and used telemetry location to estimate other nest sites, creating 2 nest data sets. I sampled 68 nests (2010, n = 27; 2011, n = 41) from 61 hens during the 2010 and 2011. Nest initiation date ranged from 23 April – 28 June with most (80%) occurring the first week of May. Most (89%) hatching occurred during the first week of June with a range of 30 May-18 June. The average number of eggs per nests was 8.2 (SE = 0.635). Most nests (75.4%) failed, and I documented hen mortality (30.9%), unknown fate (39.1%), and predation (4%) as causes of nest failure. The estimated probability of daily nest failure was 0.046 (SE = 0.006) and estimated probability of nest failure after 28 days was 0.731 (SE = 0.049). The probability of nest failure increased with increasing distance from the nearest edge, road, and stream. Ground cover was the most important microhabitat variable for nest site selection, which was 40% greater than random plots. Hens selected nests that were closer to roads but farther from edges and streams than random points based on landscape variables. Hen nesting success needs further monitoring to fully understand nesting success on the population. Roost site habitat is an important factor allowing hens a place to avoid predation and thermoregulation during the night. I estimated roost site location by taking at least 2 roost site locations after night fall using telemetry equipment from fixed ground stations. I used ArcGIS to analyze distances from buildings, edge, roads, and streams. I paired these locations with a randomly selected point in the same habitat type. I had 678 roost site locations. Distance to the nearest had the great influence on roost site selection (Table 7). Roost site were 20m farther from roads than random points, whereas distance to nearest edge and stream were similar for roost sites and random points. Protection of large tracts will ensure the quality roost habitat. Poult survival is another important factor affecting population growth. Poult survival shows managers the recruitment into the population. I used telemetry to find nest and then track successful hens. I used flush counts and lost poult calls inorder to see the hens and associated poults. I investigated poult survival from 76 collared hens. I used the 16 (2010, n = 8; 2011, n = 8) successful nests from these hens to estimate poult survival. I estimated poult survival as 0.343. and 0.525 for 2010 and 2011, respectively. My annual average poult survival was 0.434. Poult survival was excellent in Delaware and attributes to a healthy turkey population Home ranges encompass the area that is used by a turkey. This home range estimate can be used to ascertain if there is quality habitat in the area that birds use. The larger the home range could potentially mean the inferior habitat. I collected telemetry location 13 times a month from fixed ground stations. Home ranges did not differ for adult hens among seasons (50%, F3,121=0.68, P=0.565; 95%, F3,121=0.95, P=0.417) or between years (50%, F1,121=1.43, P=0.234; 95%, F1,121=1.27, P=0.263). The adult hen home range size ranged 346-971 ha and 2039-7595 ha for 50% and 95% distributions, respectively. I had too few juvenile birds to test difference in seasonal and annual home range sizes. Juveniles had larger home ranges than hens in all seasons expect the fall. Home ranges in Delaware are similar in size and suggest that there were adequate food sources to support the turkey population. Overall analyzing all aspects of reproduction in hens in Delaware, the population is stable. Nesting success clutch size and survival were all low compared to other studies; however poult survival was much greater than in other studies. The poult survival was compensating for the other deficiencies in reproduction among hens.
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