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1.
    
Intensive harvests have the potential to greatly affect local mourning dove (Zenaida macroura) populations, a popular gamebird and songbird. To evaluate if recruitment was commensurate with harvest, we applied a ratio-based method to estimate local and statewide mourning dove recruitment across 7 public hunting areas in Missouri from 2005 to 2011. We estimated recruitment from preharvest adult sex ratios and harvest age ratios that incorporated various methods to address potential inherent biases (e.g., bias in the adults of unknown sex in preharvest samples, bias in unknown age wings, and local differential vulnerability; DV). Data from 356 radio-marked doves revealed a DV rate, where hatch year doves were, on average 2.7× more likely to be harvested than adult doves. Recruitment estimates for local areas were highly variable and in some cases, biologically unrealistic (e.g., >10 offspring/female), because of small preharvest sample sizes. However, data pooled statewide provided recruitment estimates of 3.1 offspring/female (±0.3 SE) or 4.1 offspring/female (±0.3 SE), assuming samples of unknown sex doves were female biased or male biased, respectively. Although statewide estimates agree with directly observed rates, the sex ratios and differential vulnerability comprising them vary considerably from what has been previously assumed. Whether preharvest sex ratios are biased from trapping methods has 2 important implications; either regional approaches have overestimated recruitment or the number of females in Missouri's population is much less than originally thought. Because each of these scenarios are important to understanding the effects of regional harvest management on Missouri's dove population, they highlight the importance of a better understanding of biases involved in estimating recruitment. © 2012 The Wildlife Society.  相似文献   

2.
    
Riparian forests of the American Southwest are especially prone to changes in composition and structure due to natural and anthropogenic factors. To determine how breeding mourning doves (Zenaida macroura) respond to these changes, we examined nest site use and nest survival in control plots, fuel reduction plots before and after mechanical thinning, and post-wildfire sites. The greatest number of nests (50%) were located in post-wildfire sites where resprouted vegetation and woody debris provided numerous nest sites in the understory. We found fewer nests in post-treatment fuel reduction plots (17%), where most were constructed in cottonwoods, and an intermediate number of nests in control and pre-treatment plots (33%), where most were constructed in exotic plants. The best-supported logistic-exposure nest survival model indicated that survival varied among years and with date. Models containing effects of forest type, study block, and nest site selection received little support, suggesting that survival was constant among plot locations, disturbance types, and nest sites. Our nest survival estimates were low relative to those from other studies, but productivity could offset mortality if adults make numerous nest attempts each year. Our results highlight the utility of woody vegetation and debris as understory nest sites for mourning doves and other riparian birds. Managers should devise methods to preserve or reestablish these nest sites when conducting fuel reduction, exotic vegetation removal, or post-fire restoration activities. © 2011 The Wildlife Society.  相似文献   

3.
    
ABSTRACT Mourning dove (Zenaida macroura) call-count surveys in Mississippi, USA, suggest declining populations. We used available mourning dove call-count data to evaluate long-term mourning dove habitat relationships. Dove routes were located in the Mississippi Alluvial Valley, Deep Loess Province, Mid Coastal Plain, and Hilly Coastal Plain physiographic provinces of Mississippi. We also included routes in the Blackbelt Prairie region of Mississippi and Alabama, USA. We characterized landscape structure and composition within 1.64-km buffers around 10 selected mourning dove call-count routes during 3 time periods. Habitat classes included agriculture, forest, urban, regeneration stands, wetland, and woodlot. We used Akaike's Information Criterion to select the best candidate model. We selected a model containing percent agriculture and edge density that contained approximately 40% of the total variability in the data set. Percent agriculture was positively correlated with relative dove abundance. Interestingly, we found a negative relationship between edge density and dove abundance. Researchers should conduct future research on dove nesting patterns in Mississippi and threshold levels of edge necessary to maximize dove density. During the last 20 years, Mississippi lost more than 800,000 ha of cropland while forest cover represented largely by pine (Pinus taeda) plantations increased by more than 364,000 ha. Our results suggest observed localized declines in mourning dove abundance in Mississippi may be related to the documented conversion of agricultural lands to pine plantations.  相似文献   

4.
    
Previous field studies of hunter-harvested mourning doves (Zenaida macroura) have reported the percentage of birds with ingested lead shot as 0.2–6.5%. To reduce the uncertainty concerning the number of doves that ingest shot, we conducted an experiment to test the proportion of mourning doves that ingested lead shot on the bare soil of a disked field (typical of a managed dove field) to simulate more natural feeding conditions. In each of 3 treatment groups of 80 birds, we exposed 35 birds to low-density lead shot (1.5 million shot/ha), and35 birds to high-density lead shot (29.5 million shot/ha), and 10 birds served as controls (no shot). We dosed 5 positive control birds with 2 lead shot each in trials 2 and 3. We scattered lead shot and mixed seed on the loosely packed soil of treatment cages and after 4 days of exposure, 2.9% of doves voluntarily ingested ≥1 lead shot. The proportion of birds that ingested shot when exposed to the high-density shot treatment (4.9%) was not different (P = 0.098) from that of the low-density shot treatment (1.0%). Lead concentrations in liver, kidneys, and blood reached maxima of 94.402 ppm, 346.033 ppm, and 13.883 ppm wet mass, respectively. Differences in delta-aminolevulinic acid dehydratase (ALAD) activity, packed cell volume, and heterophil:lymphocyte ratio (H:L) were greater posttreatment in doves that had ingested shot than in those that did not. The risk posed to mourning doves from lead shot ingestion can be reduced by banning lead shot on management areas or dove fields or disking fields after hunting season to reduce shot availability. © 2011 The Wildlife Society.  相似文献   

5.
    
Understanding how land cover and potential competition with invasive species shape patterns of occupancy, extirpation, and colonization of native species across a landscape can help target management for declining native populations. Mourning dove (Zenaida macroura) populations have declined throughout the United States from 1965–2015. The expansion of the Eurasian collared-dove (Streptopelia decaocto), an introduced species with similar food preferences, may further threaten mourning dove populations. We analyzed data from 2009–2016 from a large-scale monitoring program in the Western Great Plains of the United States in a 2-species occupancy model to assess the effects of collared-doves on mourning dove distributions, while accounting for imperfect detection and variation in land cover across the landscape. Mourning dove occupancy was stable or increasing across our study area, and despite overlap in resource use and co-occurrence between mourning doves and Eurasian collared-doves, we found no evidence that collared-doves are extirpating mourning doves from preferred habitat during the breeding season. © 2020 The Wildlife Society.  相似文献   

6.
    
Federal migratory bird bands have been inscribed with a postal address and toll-free telephone number (toll-free bands) since 1995 for their reporting, but in 2007 the postal mail address was replaced with an internet address (web-address bands). The reporting rate of web-address bands is unknown, and knowledge of band reporting probabilities is an integral part of bird band-recovery studies designed to obtain unbiased estimates of harvest rates and recovery rates if use of band types differs across space and time. We estimated web-address band reporting probabilities for mourning doves (Zenaida macroura) in the United States by comparing the relative recovery rate (ratio) of web-address to toll-free bands and applying this as an adjustment factor to the known reporting probabilities of toll-free bands. Cooperators banded 132,386 doves representing 57,982 (44%) web-address and 74,404 (56%) toll-free bands in July and August during 2008–2010 across 34 states, 12 regions, and 3 management units. Of the birds banded, 4,642 (3.5%) were direct recoveries, as a result of being shot, and all but 3 were reported via telephone or internet. Nationally, internet reporting accounted for 16.3% of toll-free bands and 42.9% of web-address bands recovered. Web-address bands had a greater recovery rate than toll-free bands (ratio = 1.081, SE = 0.027). We found some evidence of spatial variation in ratio estimates at management unit and regional scales, but the variation was primarily at the regional level where it was not great (range = 1.015–1.213) and statistical support for this variation was not particularly strong (SE = 0.129). Nationally, the web-address band reporting probability was 0.535 (SE = 0.021), an absolute increase of 0.040 compared to the reporting probability of toll-free bands. The additional reporting probability of web-address bands relative to toll-free bands must be accounted for in band-recovery studies used to obtain estimates of harvest rates and recovery rates if use of band types differs across space and time for mourning doves and possibly other species. © 2011 The Wildlife Society.  相似文献   

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ABSTRACT Wildlife managers are becoming more concerned about the exposure of birds, in addition to waterfowl, to spent lead shot. Knowledge of hunter attitudes and their acceptance of nontoxic-shot regulations will be important in establishing new regulations. Our objective was to assess the attitudes of small game hunters in Missouri, USA, toward a nontoxic-shot regulation for small game hunting, specifically for mourning doves (Zenaida macroura). Most hunters (71.7–84.8%) opposed additional nontoxic-shot regulations. Hunters from rural areas, hunters with a rural background, hunters who hunt doves, hunters who currently hunt waterfowl, hunters who primarily use private lands, and current upland game hunters were more likely to oppose new regulations. For mourning dove hunting, most small game hunters (81.1%) opposed further restrictions; however, many non-dove hunters (57.1%) expressed no opinion. Because our results demonstrate that most small game hunters and dove hunters in Missouri are decidedly against further nontoxic-shot regulations, any informational and educational programs developed to accompany future policy changes must address their concerns.  相似文献   

9.
    
Management of migratory birds at the national level has historically relied on regulatory boundaries for definition of harvest restrictions and estimation of demographic parameters. Most species of migratory game birds are not expanding their ranges, so migratory corridors are approximately fixed. White-winged doves (Zenaida asiatica), however, have undergone significant variation in population structure with marked range expansion occurring in Texas, and range contraction in Arizona, during the last 30 years. Because >85% of white-winged dove harvest in the United States (approx. 1.3 million annually) now occurs in Texas, information on vital rates of expanding white-winged dove populations is necessary for informed management. We used band recovery and mark–recapture data to investigate variation in survival and harvest across 3 geographic strata for white-winged doves banded in the pre-hunting season in Texas during 2007–2010. We banded 60,742 white-winged doves, recovered 2,458 bands via harvest reporting, and recaptured 455 known-age birds between 2007 and 2010. The best supporting model found some evidence for geographic differences in survival rates among strata (A–C) in both hatch-year (juvenile; A = 0.205 [SE = 0.0476], B = 0.213 [SE = 0.0278], C = 0.364 [SE = 0.0254]) and after-hatch year (adult; A = 0.483 [SE = 0.0775], B = 0.465 [SE = 0.0366], C = 0.538 [SE = 0.251]) birds. White-winged doves had a low probability of moving among strata (0.009) or being recaptured (0.002) across all strata. Harvest recovery rates were concordant with estimates for other dove species, but were variable across geographic strata. Based on our results, harvest management strategies for white-winged doves in Texas and elsewhere should consider differences in population vital rates among geographic strata. © 2012 The Wildlife Society.  相似文献   

10.
    
Age and sex ratios in bag records are frequently used as indices of population composition for harvested populations. However, vulnerability to harvest may differ by age and sex thereby producing bias in population estimates. We assessed whether age and sex affected vulnerability to harvest for willow grouse (Lagopus lagopus) where adult density and brood size were known in the harvested populations. We collected bag records during 2 days of controlled hunting in 4 areas in 2 years (2007 and 2008) in Jämtland county, Sweden. We found that vulnerability to harvest was different for chicks and adults, but not between male and female adults. Hunters encountered broods at a higher rate than single birds compared to personnel conducting pre-harvest counts along line transects. Furthermore, the probability of shooting a grouse was higher in encounters of broods than individual grouse. Proportionally, we calculated about a 50% probability of a hunter shooting either a chick or an adult independent of encountering a single bird or broods of 2–10 grouse. Increasing adult density also increased the vulnerability to harvest for adults relative to chicks, independent of the chick to adult ratio in the pre-harvest population. The different vulnerability of adults and chicks to harvest observed in this study will dampen variation in age classes in bag records compared to the population, and we caution against extrapolation of age ratios in bag records to harvested populations. © 2012 The Wildlife Society.  相似文献   

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ABSTRACT Mourning doves (Zenaida macroura) are surveyed in North America with a Call-Count Survey (CCS) and the North American Breeding Bird Survey (BBS). Analyses in recent years have identified inconsistencies in results between surveys, and a need exists to analyze the surveys using modern methods and examine possible causes of differences in survey results. Call-Count Survey observers collect separate information on number of doves heard and number of doves seen during counting, whereas BBS observers record one index containing all doves observed. We used hierarchical log-linear models to estimate trend and annual indices of abundance for 1966–2007 from BBS data, CCS-heard data, and CCS-seen data. Trend estimates from analyses provided inconsistent results for several states and for eastern and central dove-management units. We examined differential effects of change in land use and noise-related disturbance on the CCS indices. Changes in noise-related disturbance along CCS routes had a larger influence on the heard index than on the seen index, but association analyses among states of changes in temperature and of amounts of developed land suggest that CCS indices are differentially influenced by changes in these environmental features. Our hierarchical model should be used to estimate population change from dove surveys, because it provides an efficient framework for estimating population trends from dove indices while controlling for environmental features that differentially influence the indices.  相似文献   

13.
    
ABSTRACT Accurately differentiating age classes is essential for the long‐term monitoring of resident New World tropical bird species. Molt and plumage criteria have long been used to accurately age temperate birds, but application of temperate age‐classification models to the Neotropics has been hindered because annual life‐cycle events of tropical birds do not always correspond with temperate age‐classification nomenclature. However, recent studies have shown that similar molt and plumage criteria can be used to categorize tropical birds into age classes. We propose a categorical age‐classification system for tropical birds based on identification of molt cycles and their inserted plumages. This approach allows determination of the age ranges (in months) of birds throughout plumage succession. Although our proposed cycle‐based system is an improvement over temperate calendar‐based models, we believe that combining both systems provides the most accurate means of categorizing age and preserving age‐related data. Our proposed cycle‐based age‐classification system can be used for all birds, including temperate species, and provides a framework for investigating molt and population dynamics that could ultimately influence management decisions.  相似文献   

14.
    
ABSTRACT Agricultural intensification is a key factor in the decline of many avian populations throughout the world, yet the exact mechanisms that contribute to these declines are relatively unresolved, especially for seed-eating species. We tested the hypothesis that forage quality, particularly protein content, limits productivity in birds consuming diets dominated by agricultural grains and lacking in native forages. We used white-winged doves (Zenaida asiatica) because columbids are highly granivorous and white-winged doves have declined in areas dominated by grain agriculture. We randomly assigned 52 pairs of captive doves to 1 of 2 treatments: we fed one treatment sorghum (Sorghum bicolor) and the second sorghum plus native seeds (croton [Croton sp.] and native sunflower [Helianthus sp.]). Birds with access to native seeds fledged 123% more young per pair, with young weighing 32% more at fledging than those fed only sorghum. Doves with access to native seeds selected a diet consisting of 43% sorghum, 32% croton, and 25% sunflower. We conclude that agricultural grains, which typically have high metabolizable energy and low to moderate protein concentrations, are not sufficient for normal productivity of white-winged doves. The lack of native forages with sufficient metabolizable energy and protein content may be a factor in the declining productivity of white-winged doves in the lower Rio Grande Valley of Texas, USA, as well as other species in regions dominated by agriculture.  相似文献   

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16.
    
Shrubs, such as mesquite (Prosopis spp.) and cholla (Opuntia spp.), now dominate fire-suppressed grasslands in southwestern North America. Responses of birds to prescribed burning of the shortgrass prairie in this region are poorly understood. We examined daily survival rates of mourning dove (Zenaida macroura) and lark sparrow (Chondestes grammacus) nests in an experimental landscape (4,811 ha) of spatially replicated, inter-annual fire frequencies (burning every 2 yr, 4 yr, or 10 yr) near Amarillo, Texas. Herbaceous habitat structure was most developed in infrequently burned plots, but shrub densities were less variable among the burn treatments. We modeled daily nest survival (DSR) against burn frequency, shrub density at nest sites, and nest stage (incubation or nestling). Daily survival of mourning dove nests was not well-related to any measured covariate, but lark sparrow DSR was negatively related to the duration of inter-annual burn frequency. In semiarid grasslands heavily inundated with shrubs, prescribed burning may positively influence the nest success of some bird species. © 2011 The Wildlife Society.  相似文献   

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18.
    
Selective harvest regimes that create female-biased sex ratios can potentially lead to delayed breeding, reduced breeding synchrony, reduced productivity, and a female-biased sex ratio of offspring. These resulting changes in breeding behavior and population dynamics have potential to adversely affect population growth. In 2002, Pennsylvania implemented harvest regulation changes that reduced deer density (increased harvest of antlerless deer) and increased the number and age of antlered deer (implemented antler point restriction regulations) that resulted in a less female-biased sex ratio. We monitored date of conception, productivity (embryos/female), and sex ratio of embryos during 1999–2006 to test if timing of breeding occurred earlier and with greater synchrony, if productivity of females increased, and if the sex ratio of offspring would shift towards more males. Deer density decreased 23% and the adult (≥1.5 yr old) sex ratio declined from 2.30 to 1.95 females/male. The ratio of ≥2.5-year-old to 1.5-year-old males shifted towards more older males (1:3.7 in 2002 to 1:1.59 in 2006) and the ≥2.5-year-old male population increased from 41,853 during 1999–2001 to 54,064 by 2006. We found no evidence of any change in the timing or variability of date of conception, productivity, or offspring sex ratio. We conclude that harvest regulation changes implemented in Pennsylvania, USA, were insufficient to affect timing of breeding or population dynamics and that efforts by managers to identify a desired sex ratio or manipulate sex ratios to achieve management goals on a statewide scale will be challenging. © 2019 The Wildlife Society.  相似文献   

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ABSTRACT We studied movements and survival of 250 female giant Canada geese (Branta canadensis maxima) marked during incubation with either satellite-monitored platform transmitting terminals or very high frequency radiotransmitters at 27 capture areas in southern Michigan, USA, in 2000–2003. We destroyed nests of 168 radiomarked females by removing eggs after day 14 of incubation, and we left nests of 82 incubating hens undisturbed after capture and marking. Of females whose nests we experimentally destroyed, 80% subsequently migrated from breeding areas to molt remiges in Canada. Among 82 nests left undisturbed, 37 failed due to natural causes and 51% of those females departed. Migration incidence of birds that nested in urban parks was low (23%) compared with migration incidence of birds that nested in other classes of land use (87%). Departure of females from their breeding areas began during the second and third weeks of May, and most females departed during the last week of May and first week of June. Based on apparent molting locations of 227 marked geese, birds either made long-distance migratory movements >900 km, between latitudes 51° and 64° N, or they remained on breeding areas. Molting locations for 132 migratory geese indicated 4 primary destinations in Canada: Western Ungava Peninsula and offshore islands, Cape Henrietta Maria, Northeast James Bay and offshore islands, and Belcher Islands, Hudson Bay, Canada. Following molt of remiges, Canada geese began to return to their former nesting areas from 20 August through 3 September, with 37% arriving on or before 15 September and 75% arriving on or before 1 October. Migration routes of geese returning to spring breeding areas were relatively indirect compared with direct routes taken to molting sites. Although overall survival from May through November was 0.81 (95% CI: 0.74–0.88), survival of migratory geese marked on breeding sites where birds could be hunted was low (0.60; 95% CI: 0.42–0.75) compared with high survival of birds that remained resident where hunting was restricted (0.93; 95% CI: 0.84–0.97). Nest destruction can induce molt migration, increase hunting mortality of geese returning from molting areas, and reduce human-goose conflicts, but managers also should consider potential impacts of increasing numbers of molt migrants on populations of subarctic nesting Canada geese.  相似文献   

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A survey of the mantled howler (Alouatta palliata) population on Hacienda La Pacifica, Guanacaste, Costa Rica, was done in July and August of 1998 to determine population parameters following deforestation due to major canal construction between 1990 and 1994. The survey was carried out in a manner identical to our 1991 survey and consisted of a single pass and two re-surveys of all forested areas of the farm. As canal construction effectively increased fragmentation of the habitat, we predicted decreased population and group size over this time. Results indicated that between the 1991 and 1998 survey, group size decreased but not significantly, and there were significantly fewer adult males and adult females per group. Population size, however, remained unchanged as there was an increase in animals in the immature age classes. An increase in the infant to adult female ratio suggests a stable or even expanding population, which could represent recovery from the initial disturbance of deforestation. Thus, despite changes in the forest and land use patterns, the area now appears to support the same number of howlers as found in previous surveys.  相似文献   

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