https://cpw.cvlcollections.org/files/original/9f669dc20f51843b5aa8edf54853a4c5.pdf 68c802113131e49cba23cc0ede08f244 PDF Text Text COLORADO DIVISION OF WILDLIFE - AVIAN RESEARCH PROGRAM FINAL PROGRESS REPORT August 2008 TITLE: Comparative Recruitment Rates of Mountain Plovers (Charadrius montanus) in Eastern Colorado AUTHOR: Victoria J. Dreitz Period Covered: January 2004 – December 2008 All information in this report MAY NOT BE PUBLISHED OR QUOTED without permission of the author. Manipulation of these data beyond that contained in this report is discouraged. ABSTRACT The mountain plover (Charadrius montanus) is a migratory shorebird which breeds on the shortgrass prairies of Colorado, Wyoming, and Montana. Continental population trends suggest a steady decline over the past century. Colorado is considered the stronghold for mountain plovers, as over half of the world’s population is believed to breed in the state. In order to develop conservation strategies for mountain plovers, we must adequately assess the relative value of each of the habitats used for breeding activity in eastern Colorado: grasslands without prairie dogs (Cynomys ludovicianus), grasslands with prairie dogs, and agricultural fields. I estimated chick survival of mountain plovers on these three habitats in eastern Colorado and the daily probability of broods moving from one habitat to a different habitat. Habitat specific density and biomass of prey availability were included as measures of habitat quality. From 2004 through 2006, 117 501 plover chick prey items were sampled and 153 mountain plover broods were monitored. The results suggest that chick survival and brood habitat transition probabilities differed among habitat types. However, these habitat associations were not explained by differences in habitat specific prey density or biomass. Chick survival was substantially higher on prairie dog habitat (0.75, CI = 0.54, 0.87) than agricultural fields (0.23, CI = 0.14, 0.33) and grassland (0.24, CI = 0.08, 0.45). However, mountain plover broods did move off prairie dog habitat. The rate of brood movement off of prairie dog habitat was lower than grassland, higher but not significantly greater than agricultural fields for each year of the study. I speculate that plover broods may move off prairie dog habitat, even though chick survival is highest on this habitat, to reduce predation pressure. Secondarily, weather events may influence chick survival and brood movements both directly and indirectly. I conclude that habitats occupied by prairie dogs are highly important to mountain plover productivity. Conservation measures that increase nest success may be ineffective for mountain plover unless they are accompanied by measures promoting chick survival. Conservation and management efforts should focus on determining what aspects of prairie dog habitat influence mountain plover reproductive success. 1 �Comparative Recruitment Rates of Mountain Plovers (Charadrius montanus) in Eastern Colorado Final Progress Report, January 2004 – December 2008 PROJECT OBJECTIVES The objective of this study is to estimate and compare mountain plover chick survival and the probability of broods moving from nesting habitat to a different habitat type used by breeding plovers in eastern Colorado – agricultural fields, native grassland not occupied by prairie dogs, and grassland occupied by prairie dogs. SEGMENT OBJECTIVES 1. To estimate and directly compare chick survival and brood movements of mountain plovers, among three habitat types (prairie dog colonies, grassland, and agricultural fields) in eastern Colorado used for breeding activity. 2. Determine if factors including individual characteristics, such as sex of the tending adult, and environmental factors, such as habitats and measure of habitat quality, influence chick survival and brood movements. 3. Summarize and analyze data and publish information in an Annual Report and professional journals. INTRODUCTION The mountain plover (Charadrius montanus) is a declining precocial shorebird that breeds throughout the prairie ecosystems of the North America Great Plains. Over the past century anthropogenic impacts have greatly altered the Great Plains landscape from expansive and diverse prairie ecosystems into small habitat patches of homogenous grasslands interspersed with agricultural lands (Smith and Lomilino 2004). Over half of the continental population of mountain plovers nests on grasslands and agricultural lands on the eastern plains of Colorado (Knopf and Rupert 1999, Knopf and Wunder 2006, Dreitz and Knopf 2007). The distribution of adult plovers across the eastern plains of Colorado during the breeding period suggests that the density of plovers on agricultural lands is similar to grasslands unoccupied by black-tailed prairie dogs (Cynomys ludovicianus), but substantially lower than grasslands occupied by black-tailed prairie dogs (Tipton 2007). Nest success on agricultural lands is equivalent to grassland habitat including grasslands occupied by black-tailed prairie dogs (Dreitz and Knopf 2007). There is little detailed information about the ecology of mountain plover chicks. Miller and Knopf (1993) calculated brood survival rate as 0.979 and the probability of a chick surviving to independence as 0.466 on grassland habitat in northeastern Colorado. Knopf and Rupert (1996) estimated daily chick survival on grassland habitat in northeastern Colorado at 10-day intervals ranging from 0.951-0.977. Lukacs et al. (2004a) found that survival was lowest immediately after hatching and quickly increased within 4 d post-hatch on black-tailed prairie dog colonies in Colorado. Dinsmore and Knopf (2005) found that fledglings tended by females had higher survival than those tended by males on black-tailed prairie dog colonies in Montana. Knopf and Rupert (1996), Lukacs et al. (2004a), and Dinsmore and Knopf (2005) indicated that daily survival rates increased with age of the chick. Mountain plover broods are capable of moving up to 2 km within 2 d of hatching (Knopf and Rupert 1999) and the area of use during the brood-rearing period is similar for broods that successfully had ≥ 1 chick reach independence and those that failed (Knopf and Rupert 1996). Knopf and Rupert (1999) reported that two out of three broods that nested on native grassland moved to an agricultural field within 2 km of the nest site. Dreitz et al. (2005) suggested that 2 �broods hatched on agricultural fields moved to different habitats, and broods hatched on habitats other than agricultural fields stayed on the nest habitat. That study was conducted on one habitat each year of the study limiting the extent of comparisons across habitats. None of these studies addressed how the use of habitats during the brood-rearing period influences chick survival. I estimated and compared chick survival and probability of brood movements among habitats for mountain plovers on three prairie habitats in eastern Colorado – agricultural fields, native grassland not occupied by prairie dogs (hereafter, grassland), and grassland occupied by prairie dogs (hereafter, prairie dog). I hypothesized that differences among habitats in prey availability may contribute to differences in chick survival and brood habitat transitions, and I obtained estimates of density and biomass of prey in each habitat. Because parental care of plover chicks in uniparental, I also include the sex of the attending parent as a potential factor influencing chick survival and brood movements. The findings are interpreted relative to conservation of this declining shortgrass prairie shorebird. STUDY AREA The study area was approximately 21,500 km² in the central eastern plains of Colorado on privately owned lands located in the counties of Cheyenne, Kit Carson, Lincoln, and Kiowa (Fig. 1). The landscape is relatively flat, arid, and dominated by pastures of native grasslands and dryland agricultural fields. Native grassland was primarily vegetated by low-growing, perennial grasses such as buffalograss (Buchloe dactyloides) and blue grama (Bouteloua gracilis), and grazed to varying degrees by domestic ungulates, primarily cattle (Bos taurus), and a native herbivore, the black-tailed prairie dog. Agricultural fields were comprised of dryland crops including wheat (Triticum aestivum L.), sorghum (Sorghum bicolor (L.) Moench), millet (Panicum miliaceum L. (Poaceae)), sunflower (Helianthus annuus L.) and corn ((Zea mays L.) and fallow fields with varying structure of dryland crop stubble. Boundaries distinguishing agricultural fields from the other habitats were well-defined. To distinguish between grassland habitats with and without prairie dogs, I defined prairie dog habitat as the prairie dog colony plus approximately a 0.40 km buffer based on similarities in vegetative structure (e.g., height, bare ground). Specific sites were selected such that a habitat was juxtaposed <2 km from one of the other two habitats to permit potential brood movements between habitats. The total area of each habitat included in the study varied between years but followed a general pattern of dryland agricultural fields ≈ prairie dog ≤ grassland. METHODS From April-August of 2004-2006, data were collected on mountain plover brood-rearing ecology. Mountain plover chicks leave the nest within 3 hr of the last egg hatching, and by the end of their first day, chicks appear capable of catching small arthropods (Graul 1973). Mountain plover chicks fledge at 33-36 d post-hatch (Graul 1975, Miller and Knopf 1993). However, I defined the brood-rearing period as hatch to 30 d post-hatch to avoid potential premature fledging of chicks. Data collection for mountain plover prey resources.—Field sampling of prey items was conducted during the primary brood-rearing period of each year at approximately two-week intervals for three consecutive days. Prey sampling occurred in known areas of plover nesting activity at the same nine sites (three replicates per the three habitats) each year of the study. Sampling sites were selected at random but restricted to one site per agricultural field or habitat patch. At each site a trapping line transect grid (Lukacs et al. 2004b) of 60 pitfall traps (Fig. 2) was installed. The trapping line transect grids were 20 m in width and 10 m in length with a center line located at the middle of the width (Fig. 2). Nine trapping line transect grids (3 grids 3 �per 3 habitats) were installed approximately one week prior to sampling and were removed after the completion of field sampling each year of the study. During sampling the traps were filled with ≈200 ml of water and <1 ml of liquid dishwashing detergent to reduce the surface tension of the water forcing arthropods to immediately sink to the bottom of the trap. Because plovers are most effective at foraging early in the morning (Knopf and Wunder 2006), sampling was conducted between the hours of sunrise (~500 MST) and 1100 MST. Contents of each pitfall trap were identified to family and genus when feasible; sorted by life stage; and dried at 60 C for 48 h to obtain dry biomass of each trap to the nearest 0.01 mg. Stomach contents from three mountain plover chicks (mean body weight 50.0 g) revealed a diet with a total dry weight biomass comprised of 52.7% ground-dwelling beetles (Order Coleoperta: e.g., darkling beetles, scarab beetles, weevils, ground beetles, etc.), 19.3% of grasshopper nymphs (Order Orthoptera) , and 14.3% ants (Order Hymenoptera); prey items were mostly 6 to 9 mm and all were <15 mm in length (Baldwin 1971). Flying arthropods would be a rare prey item because chicks are not capable of flight until 33-36 d (Graul 1975, Miller and Knopf 1993). I defined mountain plover chick prey items as arthropods that were <15 mm in length and not capable of flight. Data collect on mountain plover broods.—Nest-tending adults were captured at or near hatching using walk-in traps, and were fitted with 1.8 g radio transmitters (Advanced Telemetry Systems, Isanti, Minnesota). Radio transmitters were affixed by applying a light coating of waterproof epoxy and sliding it under the upper layer of mantle feathers so that the transmitter was positioned between feathers. This procedure enabled the transmitters to shed when the birds molted prior to their fall migration. Battery life of transmitters was expected to be ≥56 d. Additionally at capture, a US Geological Survey numbered metal band and colored plastic bands were placed on the adults and a feather sample was collected for sex determination by DNA analysis (Avian Biotech, Tallahassee, Florida). After hatching, adults with broods were located every 24 to 48 hr to record their location, habitat, and the number of chicks present in the brood. First, adults were located at distances ≥500 m to prevent forcing brood movements caused by human disturbance. From this distance, geographic coordinates of observer location, distance and bearing to each brood, habitat, and the number of chicks observed were recorded. Second, the distance to the adults with broods was decreased to confirm observation of the number of chicks. This was repeated until chicks >30 d post-hatch. Statistical methods.— To calculate the density of plover prey per habitat an approach based on distance sampling with trapping line transects was used (Lukacs et al. 2004b). The mean dry weight biomass and standard error of the trapping line transects was calculated for each habitat and year. Daily chick survival and survival over the 30-day brood rearing period was calculated using methods described by Lukacs et al. (2004a). To estimate the probability of moving from one habitat to a different type of habitat within a 24 hr period a multistate (also known as multistrata) modeling approach was used (Hestbeck et al. 1991, Brownie et al. 1993, Schwarz et al. 1993). For more details on the statistical analyses see Dreitz (In review). RESULTS Plover prey sampling.—Plover chick prey items were collected in 12 960 pitfall traps. In 2004, sampling only occurred in late May and early July because substantial rain hindered access to the trapping line transect grids in June. Of the 12 960 pitfall traps, 4.79% (621 pitfall traps) contained no plover prey items. A total of 117 501 plover prey items were collected: 26 743 (22.76%) on agricultural fields, 52 501 (44.68%) on grassland, and 38 257 (32.56%) on prairie dog. Species in the Order Hymenoptera, Family Formicidae (i.e., ants) comprised 50.53% (59 485 prey items) of the total prey items with 27.79% (32 650 prey items) and 22.84% (26 835 prey items) of the total prey items consisting of harvester ants (Myrmicinae (subfamily): 4 �Pogonomyrmex spp.) and honeypot ants (Formicinae (subfamily): Myrmecocystus spp.), respectively. The Order Coleoptera comprised the second highest number of total prey items with 31 088 prey items (26.46%). Sap beetles (family Nitidulidae) comprised 70.94% (22 055 prey items) of this Order. By habitat, the largest number of the prey items collected on agricultural fields were species in the Order Coleoptera (41.47%, 11 089 prey items of 26 743) and on grassland and prairie dog were species in the order Hymenoptera (63.78%, 33 487 prey items of 52 501 and 53.32%, 20 400 prey items of 38 257, respectively). Plover brood sampling.—A total of 214 transmitters were placed on adults with nests at or near hatching during the study (Table 1). A total of 153 adults with broods were monitored. The remaining 61 adults had their nests destroyed prior to hatching (n = 34), dropped their transmitters before eggs hatched (n = 21), or abandoned their nests (n = 6). Fewer broods from nests on grassland (n = 20 broods) were monitored than broods from nests on agricultural fields (n = 66 broods) and prairie dog colonies (n = 67 broods). Low numbers of nests located on grassland may have been due to low reproductive effort on this habitat, perhaps resulting from a lack of suitable grassland habitat for plover breeding activity during the study. More broods were tended by males (n = 79 broods) than females (n = 48 broods). This relationship did not differ by year and habitat except for on prairie dog habitat in 2006 in which an equal number of broods were tended males and females (Fig. 1). The sex of 26 adults tending to a brood was unknown due to the lack of an appropriate sample for DNA analysis. At least one chick from 28 broods was confirmed to survive from hatch to 30 d post-hatch (Table 1). Suspected chick mortality (no location on radioed adult or adult present with zero chicks on repeated observations) occurred shortly after hatching (≤ 5 d) in 2004 and 2006 but 10-18 d post-hatch in 2005. Of the 153 broods, 38 broods (25%) moved off the nest habitat to a different habitat (Table 1). The number of broods that moved off the nest habitat was similar for each of the three habitats but was higher in 2006 than 2004 and 2005 (Table 1). Of the 38 broods that moved from their nest habitat, they averaged 2.79 movement events (SD = 2.12) and 76% (n = 29 broods) were observed more often on their nest habitat than the other habitats. Average age of chicks at the first movement event occurred when chicks were slightly older in 2005 (9.25 d post-hatch, SD = 7.21) than 2004 (4.67 d post-hatch, SD = 5.40) and 2006 (4.88 d post-hatch, SD = 4.65). Of the broods that moved, mortality was confirmed (by death of the radioed adult, n=11) in 3 broods <5 d after the brood moved to a new habitat in 2006. Information on if mortality occurred after broods moved of the nest habitat in 2004 and 2005 could not be confirmed (i.e., no observation of dead adults or chicks). Chick survival.—Mountain plover chick survival differed among nest habitats. The results also indicated that differences in chick survival among nest habitats were greater than can be explained by our measures of prey density, prey biomass, year, or sex of the tending adult. Daily chick survival estimates ranged from 0.95 (CI = 0.93, 0.96) for chicks hatched on agricultural fields and grassland to 0.99 (CI = 0.98, 1.00) for chicks hatched on prairie dog colonies. Taking these estimates over the 30-day brood-rearing period, substantial differences in chick survival exist between chicks from nests on prairie dog colonies and the chicks from nests on other habitats (Fig. 4). Thirty-day chick survival on prairie dog colonies (0.75, CI = 0.54, 0.87) is approximately three times higher than agricultural fields (0.23, CI = 0.14, 0.33) and grassland (0.24, CI = 0.08, 0.45). The lack of overlap in the 95% confidence intervals between prairie dog colonies and the other habitats further suggests significant differences in chick survival on prairie dog colonies. Resighting probabilities of individual chicks decreased through the years from 0.51 (CI = 0.46, 0.56) in 2004 to 0.25 (CI = 0.26, 0.36) in 2006. Movements between habitat types.—The analysis suggested that daily probabilities of mountain plover brood movements between habitat types were influenced by the additive effect of habitat and year (Table 2). Prey density or biomass of the nesting habitat or sex of the tending adult did not have a substantial influence on brood movements to new habitats. Daily habitat transition probabilities for each habitat per year were relatively small ranging from 0.00-0.12. 5 �The 30-day brood-rearing period estimates suggest that plover broods on grassland were more likely to leave grassland and move, at a similar rate, to either agricultural fields or prairie dog habitat (Fig. 5). Movement probabilities from agricultural fields to other habitats had the lowest estimates each year, but theses estimates were not significantly different than probabilities of moving from prairie dog habitat to other habitats. Further, the results suggest that broods moved among habitats more frequently in 2006 than either 2004 or 2005 (Fig. 5). DISCUSSION Chick Survival and Brood Movements.—The findings of this study indicate that complex processes influence how different habitats affect brood-rearing activity of mountain plovers. Adults nesting on prairie dog habitat were more likely to fledge chicks (75% of the broods were successful) than adults nesting in agricultural fields (23%) or grassland (24%). However, mountain plover broods moved off of prairie dog habitat to agricultural fields and grassland at a similar rate. While the rate of brood movement off of prairie dog habitat was lower than grassland, it was slightly higher than brood movement off of agricultural fields. Brood movement off a habitat can have extensive costs to plovers in terms of survival, because of increased risks of predation and starvation while moving (Lengyel 2006, Colwell et al. 2007, Kosztolányi et al. 2007, Schekkerman and Beintema 2007). A total of 30 broods in this study were censored due to mortality of the tending adult (n=11; 9 deaths due to predation, 2 deaths due to vehicle collision), or the radio transmitter was found but fate of the adult could not be confirmed (n=19). Of the adult mortalities, 7 broods stayed on their nest habitat, and 4 broods moved to different habitat. Whereas the sample sizes are small, this suggests that mortality of the tending adult, and likely the chicks, does not increase as a result of movement to different habitats. In fact, movement to a different habitat may increase survival of chicks. The primary cause of chick mortality could not be determined in this study, but has been reported to be predation, particularly by swift foxes (Vulpes velox, Knopf and Rupert 1996). Swift foxes select grassland, specifically shortgrass prairie, over prairie dog habitat and avoid agricultural lands (Kalmer et al. 2003, Nicholson et al. 2006). The habitat selection of swift foxes may explain brood movements of mountain plovers between habitats. Plovers may use presence of swift foxes in their decision to move or not to move, and because swift foxes avoid agricultural lands there is a less of a reason to move off of agricultural lands. Additionally, when plover broods made the decision to move off a habitat, broods moved to the other habitats at a similar rate for each year of the study. That is, reducing predation pressure by moving, especially over a short time interval, may be more important than the type of habitat. Weather conditions also are known to influence chick survival and brood movements in other shorebirds (Ruthrauff and McCaffery 2005, Lengyel 2006, Kosztolányi et al. 2007). Thermoregulation of precocial chicks is positively related to their body mass (Visser and Ricklefs 1993). Extreme inclement weather may increase chick mortality due to hypothermia, risk of starvation, or direct mortality (e.g. hail, pelting rain). Less adverse weather conditions may enhance brood movements, especially for species with predators that use olfactory cues. Light precipitation events concentrate scent for predators that use olfactory cues, increasing their ability to find prey. In this study, frequent light rain events occurred throughout the brood-rearing period during 2006, which is when I observed relatively high levels of brood movement between habitats. This increased movement rate may have been a response mechanism to avoid predation. During the other years of the study, weather events were less frequent but more severe including hailstorms and flooding causing mortality of chicks, thus lower rates of brood movement occurred. I suggest that over short time intervals, weather events directly dictate plover broodrearing success, and to a greater extent over the long-term, impact the habitats used for broodrearing activity. 6 �Other factors besides predation and weather conditions may also influence brood-rearing activity of mountain plovers. Competition has been suggested to play a role in both chick survival and brood movements in other shorebirds. Intraspecific competition among Pied Avocets (Recurvirostra avosetta) for brood-rearing territories is suggested to cause brood movement out of unsuitable habitats to more suitable areas (Lengyel 2006). Similar behavior may be occurring with mountain plover broods, especially when the density of broods in a habitat patch exceeds the availability of resources, including prey and reduced predation risks. The spatial configuration of habitat patches influences the maximum density at which broods can cooccur and the distances that they can safely bridge, and deserves further study. Adequately assessing the relative value of habitats used by breeding mountain plover across the species’ range is necessary in developing conservation strategies. SUMMARY This study quantifies aspects of the mountain plover brood-rearing period among the most commonly used habitats for breeding activity in Colorado. These habitats strongly influenced mountain plover chick survival and brood movement patterns. Daily chick survival estimates for broods from each nesting habitat are within the range of those reported in other studies for mountain plovers (Miller and Knopf 1993, Knopf and Rupert 1996, Lukacs et al. 2004a, Dinsmore and Knopf 2005). Studies on other shorebird species (e.g., killdeer, Kentish plover) suggest that broods move to the habitat with the highest chick survival and stay on that habitat (Lengyel 2006, Schekkerman and Beintema 2007). In contrast, mountain plover broods did move off the habitat with the highest chick survival. The results of this 3-year study suggest that habitats occupied by prairie dogs may be important for mountain plover reproductive success. Mountain plovers are strongly associated with prairie dog habitat in Montana (Knowles et al. 1982, Dinsmore et al. 2005). Dreitz and Knopf (2007) did not find that habitat influenced nest success when categorized as either agricultural fields or grassland with or without prairie dogs. Although all of these habitats may be suitable for nesting, this study suggests that prairie dog habitat is an important habitat for brood-rearing activity. Conservation measures that increase hatching success, such as nest protection, may be ineffective for mountain plover unless they are accompanied by measures promoting chick survival. Although additional observations of spatial variability in reproductive success would aid in identifying which habitats serve as ecological traps, conservation efforts should be concentrated on habitats where survival of chicks is higher, rather than in areas where chick survival is lower. Continued conservation and management efforts should focus on determining what attributes of habitats occupied by prairie dogs (e.g., vegetation structure, percentage of bare ground, predation, prairie dog behavior) influence plover reproductive success. ACKNOWLEDGMENTS I sincerely thank the private landowners throughout eastern Colorado who provided access to their lands. Numerous individuals assisted with data collection. B. Kondratieff provided practical advice on the identification of invertebrates. P. M. Lukacs provided statistical assistance. I thank G. C. White for modifying program MARK to allow for missing values in the multistate model. The care and handling of animals was approved by the Colorado Division of Wildlife Animal Care and Use Committee (#2-2004). Financial and logistical support was provided by the Colorado Division of Wildlife. LITERATURE CITED 7 �Baldwin, P. H. 1971. Diet of the Mountain Plover at the Pawnee National Grassland, 1970-71. U.S. International Biological Program, Grassland Biome Program Report No. 134, Fort Collins, Colorado, USA. Brownie, C., J. E. Hines, J. D. Nichols, K. H. Pollock, and J. B. Hestbeck. 1993. Capturerecapture studies for multiple strata including non-Markovian transitions. Biometrics 49:1173-1187. Colwell, M. A., S. J. Hurley, J. N. Hall, and S. J. Dinsmore. 2007. Age-related survival and behavior of Snowy Plover chicks. Condor 109:638-647. Dinsmore, S. J., and F. L. Knopf. 2005. Differential parental care by adult Mountain Plovers, Charadrius montanus. Canadian Field-Naturalist 119:532-536. Dinsmore, S.J., White, G.C. & Knopf, F.L. 2005. Mountain plover population responses to blacktailed prairie dogs in Montana. Journal of Wildlife Management 69:1546-1553. Dreitz, V.J. In review. Parental behavior of a precocial species: implications for juvenile survival. Journal of Applied Ecology. Dreitz, V. J., M. B. Wunder, and F. L. Knopf. 2005. Comparative movements and home ranges of Mountain Plover broods in three Colorado landscapes. Wilson Bulletin 117:128-132. Dreitz, V. J. and F. L. Knopf. 2007. Mountain Plovers and the politics of research on private lands. BioScience 57:681-687. Graul, W. D. 1973. Breeding adaptations of the Mountain Plover (Charadrius montanus). University of Minnesota, St. Paul, Minnesota, USA. Graul, W.D. 1975. Breeding biology of the mountain plover. Wilson Bulletin 87:6-31. Hestbeck, J. B., J. D. Nichols, and R.Malecki. 1991. Estimates of movement and site fidelity using mark-resight data of wintering Canada geese. Ecology 72:523-533. Kalmer, J. F., W. B. Ballard, E. B. Fish, P. R. Lemons, K. Mote, and C. C. Perchellet. 2003. Habitat use, home ranges, and survival of swift foxes in a fragmented landscape: conservation implications. Journal of Mammalogy 84:989-995. Knopf, F. L., and M. B. Wunder. 2006. Mountain Plover (Charadrius montanus). Number 211 in A. Poole and F. Gill, editors. The Birds of North America, No. 211. The Academy of Natural Sciences, Philadelphia, Pennsylvania, and the American Ornithologists' Union, Washington, D.C., USA. Knopf, F. L., and J. R. Rupert. 1996. Reproduction and movements of Mountain Plovers breeding in Colorado. Wilson Bulletin 108: 28-35. Knopf, F. L., and J. R. Rupert. 1999. Use of cultivated fields by breeding Mountain Plovers in Colorado. Studies in Avian Biology 19:81-86. Kosztolányi, A., T. Székely, and I. C. Cuthill. 2007. The function of habitat change during brood-rearing in the precocial Kentish plover Charadrius alexandrinus. Acta Ethologica 10:73-79. Lengyel, S. 2006. Spatial differences in breeding success in the pied avocet Recurvirostra avosetta: effects of habitat on hatching success and chick survival. Journal of Avian Biology 37:381-395. Lukacs, P. M., V. J. Dreitz, F. L. Knopf, and K. P. Burnham. 2004a. Estimating survival probabilities of unmarked dependent young when detection is imperfect. Condor 106:927-932. Lukacs, P. M., A. B. Franklin, and D. R. Anderson. 2004b. Passive approaches to detection in distance sampling. Pages 260-280 in S. T. Buckland, D. R. Anderson, K. P. Burnham, J. L. Laake, D. R. Borchers, and L. Thomas, editors. Advanced distance sampling. Oxford University Press, New York, New York, USA. Miller, B. J., and F. L. Knopf. 1993. Growth and survival of Mountain Plovers. Journal of Field Ornithology 64: 500-506. 8 �Nicholson, K. L., W. B. Ballard, B. K. Mcgee, J. Surles, J. F. Kamler, and P. R. Lemons. 2006. Swift fox use of black-tailed prairie dog towns in northwest Texas. Journal of Wildlife Management 70: 1659-1666. Schekkerman H., and A. J. Beintema. 2007. Abundance of invertebrates and foraging success of Black-tailed Godwit Limosa limosa chicks in relation to agricultural grassland management. Ardea 95:39-54. Schwartz, C. J., J. F. Schweigert and A. N. Arnason. 1993. Estimating migration rates using tagrecovery data. Biometrics 49: 177–193. Smith, G. A., and M. V. Lomolino. 2004. Black-tailed prairie dogs and the structure of avian communities on the shortgrass plains. Oecologia 138:592602. Tipton, H. C. 2007. Occupancy, abundance, and density of Colorado breeding grassland birds: estimation and habitat correlations. Colorado State University, Fort Collins, Colorado, USA. Visser, G. H., and R. E. Ricklefs. 1993. Temperature regulation in neonates of shorebirds. Auk 110:445-457. 9 �Table 1. Summary of mountain plover (Charadrius montanus) broods monitored in eastern plains of Colorado, USA from 2004-2006. Year 2004 2005 2006 Total on agricultural fields 29 29 36 94 on grassland 6 8 17 31 on prairie dog colonies 20 46 23 89 21 19 26 66 males 15 7 15 37 females 5 4 11 20 unknown 1 8 0 9 5 6 9 20 males 4 4 4 12 females 1 1 2 4 unknown 0 1 3 4 17 38 12 67 males 10 15 5 30 females 5 14 5 24 unknown 2 9 2 13 Broods that fledged chicks 10 14 4 28 Broods moved from nest habitat 6 8 24 38 on agricultural fields 1 2 8 11 on grassland 2 2 7 11 on prairie dog colonies 3 4 9 16 Transmitters placed on nesting adults Broods monitored initially located on agricultural fields initially located on grassland initially located on prairie dog colonies 10 �Table 2. Summary of model selection results for mountain plover chick survival and brood movement activity in the eastern plains of Colorado, USA, 2004-2006. Models with a ΔAICc <20 units are presented in ascending by AICc, with ΔAICc indicating the difference between each model and the model with the lowest AICc value. Model K† AICc‡ ΔAICc Chick Survival Brood Movement   habitat  p  year  6 2497.62 0.00   year + prey density  p  year  7 2504.14 6.52   year + habitat  p  year  8 2507.00 9.38   sex of tending adult  p  year  5 2517.22 19.61 ψ  habitat + year  p  year  12 1634.13 0.00 Notes: For chick survival, apparent survival (  ), included the effects of habitat, year, sex of the tending adult, and plover prey density. Resighting probability (p) included the effect of year. For brood movement, brood movement ( ψ ) included the effects of habitat and year resighting probability (p) included the effect of year. † The number of parameters. ‡ Akaike’s Information Criteria 11 �Figure Legends Figure 1. Study region in the central eastern plains of the state of Colorado, USA. The study region is grey shaded and approximately 21,500 km2, located on privately owned agricultural and ranch lands. Figure 2. Top: Schematic diagram of pitfall trapping line transect grid with the center line noted by the dashed line. Bottom: View of the center line of the trapping line transect grid on grassland habitat. The pitfall traps are covered with plastic lids when sampling did not occur. This transect grid was established to estimate density and biomass of mountain plover prey resources on agricultural fields, grassland, and prairie dog colonies in the central eastern plains of Colorado, USA, 2004-2006. Figure 3. Estimates of density (A) and biomass (B) and 95% confidence intervals for mountain plover prey resources on agricultural fields, grassland, and prairie dog colonies in the central eastern plains of Colorado, USA, 2006-2006. Figure 4. Estimates of chick survival and 95% confidence intervals for mountain plovers nesting on agricultural fields, grassland, and prairie dog colonies in the central eastern plains of Colorado, USA, 2004-2006. Estimates are presented for the brood-rearing period, hatch to 30 d post-hatch. Figure 5. Estimates of mountain plover brood movement probabilities and 95% confidence interval in the central eastern plains of Colorado, USA, 2004-2006. A movement event is defined as moving from one habitat to a different type of habitat within 24 hr period. The habitats are defined as agricultural fields (AG), grassland (GR), and prairie dog colony (PD). Estimates are presented for the brood-rearing period, hatch to 30 d post-hatch. 12 �13 �10 m 20 m 14 �2004 2005 2006 1600 1400 A Density (ha * 100) 1200 1000 800 600 400 200 0 Ag Fields Grassland 5000 Prairie Dog 2004 2005 2006 4500 4000 Biomass (g) 3500 3000 2500 2000 1500 1000 500 0 Agricultural Fields Grassland Habitat 15 Prairie Dog B �1.0 0.9 Survival Probability 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 Agricultural Fields Grassland Habitat 16 Prairie Dog �1.00 0.90 Movement Probability 0.80 0.70 0.60 2004 0.50 2005 2006 0.40 0.30 0.20 0.10 0.00 AG→GR AG→PD GR→AG GR→PD Habitat transition 17 PD→AG PD→GR � Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Reports Text A resource consisting primarily of words for reading. Examples include books, letters, dissertations, poems, newspapers, articles, archives of mailing lists. Note that facsimiles or images of texts are still of the genre Text. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Comparative recruitment rates of mountain plovers (<em>Charadrius montanus</em>) in eastern Colorado Description An account of the resource The mountain plover (<em>Charadrius montanus</em>) is a migratory shorebird which breeds on the shortgrass prairies of Colorado, Wyoming, and Montana. Continental population trends suggest a steady decline over the past century. Colorado is considered the stronghold for mountain plovers, as over half of the world’s population is believed to breed in the state. In order to develop conservation strategies for mountain plovers, we must adequately assess the relative value of each of the habitats used for breeding activity in eastern Colorado: grasslands without prairie dogs (<em>Cynomys ludovicianus</em>), grasslands with prairie dogs, and agricultural fields. Creator An entity primarily responsible for making the resource Dreitz, Victoria J. Subject The topic of the resource Mountain plover <em>Charadrius montanus</em> Colorado Wyoming Montana Wildlife management Extent The size or duration of the resource. 17 pages Date Created Date of creation of the resource. 2008 Rights Information about rights held in and over the resource <a href="http://rightsstatements.org/vocab/NoC-NC/1.0/">No Copyright - Non-Commercial Use Only</a> Type The nature or genre of the resource Text Format The file format, physical medium, or dimensions of the resource application/pdf Language A language of the resource English