Hen Success Research Articles

Backpack satellite transmitters reduce survival but not nesting propensity or success of greater sage-grouse.

Telemetry technology is ubiquitous for studying the behavior and demography of wildlife, including the use of traditional very high frequency (VHF) radio telemetry and more recent methods that record animal locations using global positioning systems (GPS). Satellite-based GPS telemetry allows researchers to collect high spatial-temporal resolution data remotely but may also come with additional costs. For example, recent studies from the southern Great Basin suggested GPS transmitters attached via backpacks may reduce the survival of greater sage-grouse (Centrocercus urophasianus) relative to VHF transmitters attached via collars that have been in use for decades. While some evidence suggests GPS backpacks reduce survival, no studies have examined the effects of GPS backpacks on breeding behavior and success. Therefore, we compared survival, breeding behavior, and nest success of sage-grouse hens marked with both VHF collars and GPS backpack transmitter over a 7-year period in central Idaho, USA. GPS backpacks reduced spring-summer survival of sage-grouse hens relative to hens with VHF collars, where daily mortality probability was 68%-82% higher from March 1 to August 1. Yet satellite GPS backpacks did not consistently affect nest success or the likelihood or timing of nest initiation relative to VHF collars. Daily nest survival varied annually and with timing of nest initiation and nest age, but marginal effects of transmitter type were statistically insignificant and interactions between transmitter type and study year produced no meaningful patterns. Our results corroborate recent studies for the effect of satellite GPS backpacks on sage-grouse survival, but also suggest that these transmitters do not appear to affect components of fecundity. Our results therefore add important context to recent debate surrounding the effects of GPS backpacks on sage-grouse, and the relative strengths and weaknesses of different transmitter types for understanding behavior and population dynamics.

Survival and Reproduction of Parent-Reared Northern Bobwhites

Captive-reared and released game birds typically have low reproductive success in the wild which limits their use for restoration of game bird populations. A fundamental problem with captive-rearing techniques is the absence of a mechanism for imprinting. We developed a parent-rearing technique that facilitates pre- and post-hatch imprinting using parent-reared wild strain northern bobwhite (Colinus virginianus) chicks in outdoor pens. Parent-reared chicks were marked with patagial wing tags and recaptured during October and the following March. We radiomarked juveniles captured in March to monitor survival and reproductive success in two separate studies, one in Georgia, and one in South Carolina, USA. Band-recapture survival estimates of parent-reared chicks from release to the following breeding season in Georgia (2005–2007) averaged 0.12 (range 1⁄4 0.06 to 0.25) and was dependent on release period. Radio- marked, parent-reared bobwhites had lower survival than wild bobwhites and produced 0.3 nests per hen for the breeding season versus 1.0 nests per hen for radio-marked wild resident bobwhites. Nesting success and subsequent chick survival did not differ among groups, but sample sizes were small. Radio-marked, parent-reared hens (n 1⁄4 26) in the South Carolina study (2008–2010) produced 0.67 nests per hen for the breeding season versus 0.62 nests per hen for radio-marked wild resident hens. Nesting success and brood-rearing success of parent-reared hens did not differ from that of wild resident hens and breeding season survival was also similar. Survival and reproduction of parent-reared wild strain bobwhites were greater than previously reported for pen-reared bobwhites and may useful for restoring or enhancing bobwhites populations at the local scale.

Influence of patch shape on mallard nest survival in northern Iowa

Reproductive success of mallards (Anas platyrhynchos) is influenced by distribution and amount of wetlands and grasslands on the landscape during the breeding season. Most studies of mallard reproductive success have been conducted in areas with high wetland densities and large tracts of grasslands. We investigated nest survival of mallards in intensively cropped northern Iowa, USA, where wetland and grassland habitats were highly fragmented. We radiotracked female mallards nesting during 1998–2000 and located 318 nests in 6 types of land cover. Overall daily survival rate of nests was 0.945 ± 0.003 standard error (SE), corresponding to an estimated nest survival rate of 0.14. Hen success (i.e., the probability that an individual female will hatch a nest in one of her attempts) averaged 0.28 ± 0.03 SE. We used a model selection approach to examine covariates that might affect nest survival. Perimeter-to-area ratio (PAR) of the nest patch was the most important predictor of daily nest survival, with nest survival decreasing with increasing PAR. A greater percentage of nests hatched (18%) in habitats with low perimeter-to-area ratios (e.g., pastures, hayfields, Conservation Reserve Program fields, and managed grasslands) compared with habitats with high PAR (11%) such as drainage ditches, road-side ditches, fencerows, and waterways. Managing habitat in this region to increase mallard nest survival will be challenging, given the propensity of mallards to nest in linear habitats. If the climate change projections materialize in the 21st century, the southeastern portion of the Prairie Pothole Region could become a much more important breeding area for midcontinent mallards. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Using sightability‐adjusted brood‐pair ratios to estimate waterfowl productivity

ABSTRACTHistorically, biologists used brood‐pair ratios (BPRs) as an index to waterfowl productivity to help guide management decisions and evaluate conservation practices. However, BPRs are biased by imperfect detection probabilities, especially for broods. We conducted roadside surveys for breeding waterfowl pairs on 7–8 study sites in the springs of 2006–2008 in northeastern North Dakota, USA. Later each year, we conducted replicate counts of broods on the same wetlands and used mark–recapture methods to estimate sightability‐adjusted BPRs (SA‐BPRs). Traditional roadside brood surveys detected only 30–45% of the available broods, depending on species. We explored the potential for using SA‐BPRs to measure hen success (i.e., the probability a female hatches ≥1 egg across all nesting attempts) for mallards (Anas platyrhynchos) and other upland‐nesting dabbling ducks (Anas spp.). We found that SA‐BPRs explained 40% of the variation in hen success over 5 species of dabbling ducks, and we were able to detect an effect of predator reduction on hen success in combined dabblers, but not in mallards alone. However, we found no relationship between SA‐BPRs and mallard fledging rates (hen success × initial brood size × duckling survival). Our results suggest that SA‐BPRs can provide a cost‐effective alternative to traditional measures of productivity such as nesting success, but not to measures of duckling survival. Nevertheless, SA‐BPRs may be useful in areas where traditional measures of waterfowl productivity are logistically or financially challenging. © 2014 The Wildlife Society.

Mid‐contract management of Conservation Reserve Program grasslands provides benefits for ring‐necked pheasant nest and brood survival

AbstractConservation Reserve Program (CRP) fields may provide good habitat for nesting and brood‐rearing ring‐necked pheasants (Phasianus colchicus) during early stages of succession. But, the success of hens in early successional CRP, relative to late successional CRP and other grassland habitats, has yet to be evaluated. The reproductive period is especially critical for populations of pheasants, and CRP's benefits to hens and chicks may decrease as fields age because of loss of vegetative diversity, decrease in vegetation density, and accumulation of residual litter. During 2005–2006, we evaluated spatial and temporal variation in nest and brood survival for radio‐marked hen pheasants in areas of northeastern Nebraska where portions of CRP fields had been recently disced and interseeded (DICRP) with legumes. Nests in DICRP tended to have a higher daily survival rate (0.984; 95% CI: 0.957–0.994) than nests in grasslands (including CRP) that were unmanaged (0.951; 95% CI: 0.941–0.972). The probability of 23‐day nest success was 0.696 (95% CI: 0.631–0.762) for DICRP and 0.314 (95% CI: 0.240–0.389) for unmanaged grasslands. Daily brood survival rates varied by habitat type, brood age, and date of hatch. The probability of a brood surviving to day 21 was 0.710 (95% CI: 0.610–0.856). Brood survival rates increased with time spent in DICRP and as the brood aged. Survival decreased as broods spent more time in cropland and peaked seasonally with broods that hatched on 15 June. Brood survival probability, to 21 days, would be reduced to 0.36 (95% CI: 0.100–0.701) if broods in our sample had not used DICRP. We combined nest and brood survival in a productivity model that suggested 2,000 hens, in a landscape with no DICRP, would produce 1,826 chicks, whereas the same hens in a landscape of 100% DICRP would produce 5,398 chicks. Production of first‐year roosters more than doubled when hens nested in DICRP. Without DICRP, population growth rates of pheasant populations usually declined; with DICRP, populations stabilized with at annual survival rates of 0.3 or greater. The positive response of nest and brood survival to discing and interseeding CRP provides further evidence that CRP fields must be managed to optimize wildlife benefits. © 2012 The Wildlife Society.

Nesting Biology of Mallards in West-central Illinois

The number of Mallards (Anas platyrhynchos) breeding in Illinois and eastern North America has increased in recent decades; however, few studies have investigated the nesting biology of Mallards outside primary production areas. Therefore, we radiomarked resident female Mallards (n = 148) in west-central Illinois during 1998–2003 to assess nesting parameters and evaluate recruitment. Mean initiation date for first nests ranged from 22 April to 6 May, and the majority (75%) of nests were initiated by 20 May. Therefore, the majority of nests were predicted to hatch by 24 June. The nesting season averaged 88 days (range: 77–103 days). The proportion of unsuccessful females that renested ranged from 50.0–85.7%, and adults were more likely to renest (75.0%) than yearlings (48.0%). Nest success ranged from 9.8–33.3% and was 19.6% overall; hen success was 28.3%. Initial brood size was 8.2 ± 0.3 ducklings, but brood size declined to 3.0 ± 0.6 ducklings by 17 days posthatch. Brood survival to 20 days was 0.759 ± 0.081, and 20-day duckling survival was 0.413 ± 0.035. Female survival during spring-summer ranged from 0.546–1.00 and averaged 0.710 ± 0.096. Likewise, estimated Mallard recruitment varied annually (range: 0.302–0.672 female ducklings/female). Assuming constant female and duckling survival, we estimated that a recruitment rate of 0.613 female ducklings/adult female was necessary to maintain a stable Mallard breeding population in west-central Illinois. Estimated Mallard reproduction and recruitment was similar to that observed in other areas of North America. Nest success and hen success approached or exceeded estimated thresholds for population stability in most years; however, hen success averaged over the study period was insufficient for local population maintenance and growth. Female survival was comparable to that observed in other studies but may have limited population growth in some years. Duckling survival was sufficient for population maintenance. Management designed to enhance hen success and brood habitat may augment Mallard recruitment in west-central Illinois.

Demographics of Breeding Female Mallards in Southern Ontario, Canada

Reliable estimates of breeding-ground demographic rates are needed to develop effective conservation strategies for mallard (Anas platyrhynchos) breeding habitat in eastern North America. We radiomarked 224 female mallards in an agricultural landscape in southern Ontario, Canada, during 1997–2000. At each of 4 sites, 1 during each year, we estimated survival of adult females, breeding incidence, nesting effort, clutch size, nesting habitat use, nest survival, and hen success. We also examined the influence of nest age, date, and habitat on nest survival and the influence of date and female age on survival of adult females. Almost all females remaining on site were observed to initiate ≥1 nest (x̄ = 0.97, range = 0.95–0.98), we detected a mean of 2.07 (1.80–2.36) nests per female each season, and full clutch size averaged 9.56 (9.1–10.0). For most sites, females nested in grassland and hay land more than expected relative to habitat abundance, nested in wetlands and woody habitats in proportion to abundance, and avoided cropland and developed areas. Survival of adult females from 25 March to 15 July averaged 0.75 (0.65–0.84). Estimates from our best model showed relatively uniform survival across the breeding season, with the exception of large decreases for 2 sites during the peak of the onset of hay cutting. Nest survival averaged 0.13 (0.11–0.15). Our best model supported increasing survival with nest age but did not include variation relative to habitat or date, except in hay land. Nest survival in hay land was high relative to other habitats early in the nesting season, but declined sharply with the onset of hay cutting. Hen success averaged 0.37 (0.25–0.46). Because estimated nest survival varied little among sites and habitats and because suitable nesting habitat appeared abundant, we suggest that upland habitat conservation will accrue only limited demographic benefits. Incentives to alter hay-cutting practices may decrease mortality of nests and nesting females, but we believe such incentives are unlikely to be cost efficient and that experiments would be needed to reliably assess benefits.

Experimental evaluation of duck nesting structures in Prairie Parkland Canada

Abstract Overwater nesting structures for ducks have been used primarily to increase mallard (Anas platyrhynchos) production where success of ground-nesting hens was low (<15%), such as in the Prairie Pothole Region (PPR) in North America. However, managers have inquired about recommended numbers of nest structures for small wetlands (i.e., <2 ha) based on duck-production and benefit–cost evaluations, but such data were not available. Therefore, we conducted an experiment in the PPR in Manitoba, Canada, in 2001 and 2002 to test the effects of different treatment numbers of nest structures/wetland (1, 2, or 4) and wetland area (≤0.4 or 0.45–1.5 ha) on use of structures by nesting ducks, nest success, and number of ducklings produced, as well as to evaluate cost–benefits of the structures. Across duck species, mean use of structures by nesting hens increased 56% between years (F1,107 = 14.29, P <0.001); however, by year 2 use did not differ among treatment numbers of structures and averaged 78% (t157 =−0.15...

Influence of precipitation on demographics of northern bobwhites in southern Texas

Northern bobwhite (Colinus virginianus) populations in southwestern rangelands are influenced by precipitation; populations increase during relatively wet periods and decrease during drought. Understanding the demographic responses of bobwhites to fluctuations in precipitation might provide a basis for identifying mechanisms responsible for the phenomenon. We compared 10 population variables (bobwhite survival, nesting-season length, nest success, hen success, percent hens nesting and renesting, nesting rate, percent juveniles in fall harvest sample (Nov-Feb), clutch size, and egg hatchability) between a dry (Sep 2000–Aug 2001; 51 cm precipitation) and wet period (Sep 2002–Aug 2003; 93 cm precipitation) in Brooks County, Texas. We monitored radiomarked bob-whites on 3 sites during the dry (n=263 bobwhites) and wet period (n=191 bobwhites) to obtain estimates of survival and reproductive effort. Bobwhite survival curves differed between the dry period (0.30±0.04; ŜS±SE, n=102 bobwhites) and wet period (0.60± 0.06; n=71 bobwhites; P ≤ 0.001) during fall-winter (Sep-Feb). A lower proportion of hens nested during the dry period (95% CI: 52.6±22.5 %; n=19 hens) compared to the wet period (100%; n=15 hens). Of hens that nested, the dry period exhibited a lower nesting rate (95% CI: 1.2±0.3 nests/hen) compared to the wet period (95% CI: 2.3±0.5 nests/hen). The dry period also experienced a shorter nesting season (69 days) compared to wet period (159 days). Lastly, percent juveniles (Nov-Feb) was lower during the dry period (95% CI: 69.3±0.3 %; n=740 harvested bobwhites) compared to wet period (95% CI: 78.3±2.1%; n=1,415 harvested bobwhites). Our field study highlights 4 demographic variables (i.e., survival, percentage of hens nesting, nesting rate, and nesting-season length) that warrant further research to identify causal factors responsible for the boom-and-bust phenomenon in bobwhites. Further, our data suggest that drought negatively impacts bobwhite reproductive effort such that harvest should be reduced or ceased during drought (e.g., <50 cm annual precipitation).

Mallard and Black Duck Breeding Parameters in New Brunswick: A Test of the Reproductive Rate Hypothesis

Divergent population trends of mallards (Anas platyrhynchos) and black ducks (Anas rubripes) in eastern North America have been attributed to differences in reproductive rates. In order to test this hypothesis, we compared breeding parameters of radiomarked mallards and black ducks in an agricultural environment in midwestern New Brunswick. No differences in clutch size, nest success, hen success, duckling survival, or hen survival were detected during the breeding season. Reproductive success of both species appeared to be at or above the level needed to maintain population size. These results support a growing body of evidence that mallards are not more productive than black ducks in agricultural or forested environments. Moreover, earlier studies indicate no difference in annual survival rates between the 2 species. Given the failure of this and other studies to detect differences in vital rates of the 2 species, divergent population trends of mallards and black ducks present somewhat of a paradox. We hypothesize that differences in the population status of mallards and black ducks are the result of differences in breeding propensity that may arise from competition for breeding resources.

Reproduction in a Declining Population of Wild Turkeys in Arkansas

Wild turkey (Meleagris gallopavo) abundance in the Ouachita Mountains of Arkansas has declined since 1987. We studied reproductive output of 106 radiotagged hens from 1993 to 1996 to understand factors likely responsible for this decline. Low rates of initiation of incubation (65% for adult and 53% for subadult hens), low nesting success (13%), and small clutch sizes (9.0/adult hen, 7.8/subadult ben) characterized the population. Mean hen success was 0.20 for adult hens and 0.10 for subadult hens. Survival of poults (34% at 2 weeks posthatch) and hens during the breeding season (Kaplan-Meier survival estimates = 74.8% for adults and 79.1% for subadults) was likely not responsible for the population decline. Heavier hens laid larger clutches and presumably entered the nesting season in better condition, leading to earlier initiation of incubation and greater probability of successful nesting. Hens entering the nesting season in poor condition reduced clutch size investment or delayed nesting. Management efforts aimed at increasing hen condition prior to nesting could produce increases in reproduction.

The effects of demonstrator social status and prior foraging success on social learning in laying hens

Opportunities for social learning within a group of animals are likely to be influenced by the social dynamics of that group. Some individuals may be more influential demonstrators than others even when there are no differences in their skill level or performance. In this study of domestic hens,Gallus gallus domesticus, differences in demonstrator salience were examined. From 24 separate flocks we selected as demonstrators a dominant cockerel, a dominant hen, a mid-ranking hen or a subordinate hen. Demonstrators were pretrained to perform an operant discrimination task to obtain food. Six observers from each flock individually watched the demonstrator perform the task for four 5-min sessions held on consecutive days. On the fifth day observers were tested individually in the operant chamber. We analysed data from 19 flocks, where there were no quantitative differences in demonstrator performance. Observer hens of relatively high social status performed more correct operant pecks than observer hens of relatively low social status. Demonstrator category also had a significant effect on subsequent observer behaviour. Hens that had observed cockerels performed very few general pecks or operant pecks. Hens that had observed dominant hens performed more operant pecks, but hens that had observed sub-ordinate hens performed more general pecks in the chamber. The results suggested either that there was an interaction between dominance and gender in demonstrator salience or that dominant hens might have been influential because of some factor imperfectly associated with their dominance status. A possible candidate was the foraging ability of the dominant hens. In a second experiment using the same protocol, we manipulated the prior foraging success of dominant hens from four additional flocks but this had no significant effect on their subsequent influence as demonstrators.

Impact of radio‐tracking on black grouse Tetrao tetrix reproductive success in the French Alps

From 1991 to 1995, we tested the effects of radio‐tracking, including trapping, handling and monitoring, on reproductive success of black grouse Tetrao tetrix hens in the southern French Alps. Reproductive success (total young/total hens with and without broods) was lower in hens marked with radio‐collars than in unmarked hens (0.77 vs 1.66 young/hen, P = 0.02). Brood size was similar in the two groups of hens, but the proportion of hens rearing a brood was lower among marked hens (23 vs 45%, P = 0.03). Reproductive success of hens marked at the beginning of laying, or just before, was lower than that of hens marked ≥6 months before laying (0.25 vs 1.20 young/hen, P = 0.058). The success of hens marked near the time of laying was also low compared with unmarked hens in all years but 1992 (the year*time of capture interaction was significant). In contrast, reproductive success of hens marked ≥6 months before laying was not statistically different from that of unmarked hens (1.20 vs 1.66 young/hen, P = 0.28). Higher predation rates on first clutches, and to a lesser extent lower ability to renest, were responsible for the lower reproductive success of hens marked at the beginning of or just before laying. Altogether, these results suggest that initial discomfort caused by the transmitter, stress of capture, handling and monitoring following capture may temporarily alter the behaviour of hens, thereby increasing detection of their nests by predators. After a period of adjustment, radio‐transmitters per se may have little or no adverse effect on reproduction. We conclude that to obtain reliable estimates of breeding parameters of black grouse in the French Alps using necklace type transmitters, hens must be equipped with these several months before laying, and nesting hens should not be approached closer than 20 m during radio‐tracking.

Reproductive Characteristics of a Wild Turkey Population in Central Mississippi

Long-term investigations into wild turkey (Meleagris gallopavo) reproduction are needed to allow for annual fluctuations, illuminate trends not evident from short-term data, and provide data for effective sustainable management of the wild turkey resource. We used 13 years (1984-96) of continuous data to estimate reproductive parameters of a wild turkey population in central Mississippi. Mean rates of reproductive parameters were 72.3% for first-nest initiation rates, 27.9% for first-nest success, 34.8% for renest initiation, and 24.6% for renest success. Median date of incubation ranged from 12 April to 1 May. Juvenile hens did not contribute to reproduction. Hen success declined significantly over time and reflected a decreasing population. Most (51.1%) nest failures were attributed to predation. Poult survival until late July-August was 25.5%. Winter weather did not influence reproductive parameters, and hen experience did not increase nest success. Mean hen success for this population was the lowest reported for any eastern wild turkey (M. g. silvestris) population. Low hen success via lack of productivity from renest attempts, lack of juvenile hen reproduction, and low nest success may have contributed to the population decline. A simplistic population model indicated that, given current reproduction and hen survival, maintaining wild turkeys as a closed population on our area is doubtful.

Reproductive Ecology of Eastern Wild Turkeys in Southwestern Wisconsin

Developing sound harvest strategies for wild turkey populations requires geographically specific information on population dynamics. The absence of this information prompted us to investigate the reproductive ecology of a hunted population of eastern wild turkeys (Meleagris gallopavo silvestris) in southwestern Wisconsin during 1989-92. Nesting rates averaged 0.927 and were higher for adults than subadults (P = 0.003, n = 220). No age-specific differences were detected for renesting rates (P = 0.413, n = 147), nest success for first (P = 0.549, n = 199) or second (P = 0.685, n = 81) attempts, mean clutch size (P = 0.300, n = 37), or mean number of eggs hatched (P = 0.304, n = 24). Hen success averaged 0.217 (n = 212). Hen success was higher for adults than subadults (P = 0.047) and did not vary among years (P = 0.254). Mammalian predation was the primary factor affecting reproductive success. The level of recruitment during the study was inadequate to maintain the population.

Survival and Reproduction of Female Wild Turkeys in New York

Annual fluctuations of northern wild turkey (Meleagris gallopavo silvestris) populations often are attributed to high winter mortality. However, studies conducted in agricultural environments have demonstrated that seasonal survival can be highest during winter, suggesting other factors are more important to annual population change. We examined survival and reproduction of female eastern wild turkeys in south-central New York during 1990-93 and conducted a sensitivity analysis to determine the relative importance of demographic parameters to annual population change. Seasonal survival rates (n = 238) were 0.800 for spring, 0.855 for summer, 0.834 for fall, and 0.873 for winter. Fall survival rates varied by years (P < 0.01) and were higher during years of above average hen success. Annual survival rates averaged 0.498, and crude annual mortality rates (M) averaged 0.321 for predation and 0.117 for poaching, hunting, and wounding combined. Subadult females had lower nesting rates (P = 0.002, n = 201), lower renesting rates (P = 0.001, n = 115), and lower hen success rates (P = 0.02, n = 196) than adult females. Nest success averaged 37.9% (n = 232) and was highest (P = 0.005) during years with average to below average May rainfall. We observed annual variation in nest success (P = 0.001), hen success (P = 0.003), and hatching rates (P = 0.04). Poult survival averaged 40.0% (n = 605) and did not vary among years (P = 0.73). Nest success was the primary factor contributing to annual population change. We suggest that annual fluctuations of northern populations in mixed agricultural and forested environments rarely result from variability of annual survival and may result from variability of annual nest success and poult survival. Northern populations subjected to infrequent severe winters in mixed agricultural and forested environments likely would benefit more from enhancement of nesting and brood-rearing habitat.

Reproduction and Survival of Female Mallards in the St. Lawrence River Valley, New York

Few studies of mallards (Anas platyrhynchos) have been conducted in northeastern habitats where mallard populations have increased in abundance since the 1960s and dominate many breeding communities of dabbling ducks. We investigated the breeding ecology of female mallards within the St. Lawrence River Valley (SLRV) of northern New York, from March to july 1990-92, to determine factors affecting reproductive success and survival. Nest success (x = 18%, n = 67) was highest (P < 0.10) in haylands (39%), followed by wetlands (14%), grasslands (8%), and shrublands (3%); predation caused 92% of nest failures. Hen success averaged 18% (n = 84) and was 25% (n = 44) for after-second-year (ASY) females and 11% (n = 36) for second-year (SY) females. Daily survival rate (DSR) of radio-marked females was lower (P = 0.009) during the breeding season (DSR = 0.996, SE = 0.0009, n = 94) than postbreeding season (DSR = 0.999, SE = 0.0007, n = 66). At least 33% of female mortality occurred at nest sites, and avian predators accounted for 6 of the 15 females killed during the breeding season. Estimated brood survival from nest to water was 0.92 (95% CI = 0.85-1.0, n = 13). Management of mallards in the SLRV should focus on maintaining an agricultural land base and protecting wetlands

Nesting Effort by Wild Mallards with 3 Types of Radio Transmitters

Although radio transmitters have been used extensively in waterfowl research for 20 years, effects of these devices on wild breeding mallards (Anas platyrhynchos) are largely unknown. Therefore, we compared various measures of nesting effort for mallards radiomarked with harnessed backpacks, sutured backpacks, and abdominal implants. The proportion of females that nested varied (P < 0.05) by transmitter type: 5 of 9, 16 of 16, and 5 of 5 females nested with harnessed backpacks, implants, and sutured backpacks, respectively. Females with harnessed backpacks initiated fewer (P < 0.0001) nests than birds with other transmitter types and devoted fewer (P = 0.007) days to egg laying and incubation than birds with implants. Our results suggest that studies using harnessed backpacks may underestimate nesting effort, hen success, and recruitment

Nesting Ecology of Merriam's Turkeys in the Black Hills, South Dakota

Merriam’s wild turkeys (Meleagris gallopavo merriami) were introduced to the Black Hills approximately 40 years ago, and recent population estimates show a large and stable population. Until now, few studies have evaluated nesting ecology of Merriam’s turkeys, and none occurred in predominantly pure ponderosa pine (Pinus ponderosa) forests. Thus, we studied nesting and nest habitat factors that influence population productivity using a hierarchical approach in the Black Hills, South Dakota. In contrast to other studies, yearling Merriam’s turkey hens showed a high propensity to nest. Nest survival for adult hens did not differ (P = 0.18) from yearlings, but adult hen success was higher (P = 0.03). April-June precipitation was positively related (R2 = 0.93, P Corvus brachyrhynchos; hereafter referred to as crows). Among macrohabitats (third-order habitats), there were no (P = 0.45) patterns of nest site selection. Among microhabitats (fourth-order habitats), hens selected small sites (<5 m across) with obstructed view of the nest and vegetation averaging 2.3 dm tall. Few microhabitat differences occurred between successful and unsuccessful nests, and those that did were related to higher (P = 0.02) survival of third nest attempts. Our data indicate that availability of nest habitat was not limiting turkey populations in this area.

Influence of Age and Selected Environmental Factors on Reproductive Performance of Canvasbacks

Age, productivity, and other factors affecting breeding performance of canvasbacks (Aythya valisineria) are poorly understood. Consequently, we tested whether reproductive performance of female canvasbacks varied with age and selected environmental factors in southwestern Manitoba from 1974 to 1980. Neither clutch size, nest parasitism, nest success, nor the number of ducklings/brood varied with age. Return rates, nest initiation dates, renesting, and hen success were age-related. Return rates averaged 21% for second-year (SY) and 69% for after-second-year (ASY) females (58% for third-year and 79% for after-third-year females)