Percentage Of Nests Research Articles

Climate Extremes in Consecutive Years Impacted the Number and Fate of Duck Nests on Great Salt Lake Marshes.

The number of ground-nesting ducks in the marshes of Great Salt Lake (GSL), Utah has drastically decreased in the past few decades. One potential cause for this decline is the increase in climate extremes caused by global warming. From 2019 through 2023, GSL marshes experienced 1 year of historic spring rainfall (2019), 2 years of historic droughts (2021 and 2022), and 1 year of record snowfall (2023). We used this time period to test the hypothesis that climate extremes impact both the number of duck nests and their fate (i.e., successful, depredated, or abandoned). We counted 563 nests of cinnamon teal (Spatula cyanoptera), 168 mallards (Anas platyrhynchos), and 220 gadwalls (Mareca strepera). Nest numbers varied among years and were positively correlated with the amount of spring rainfall (April and May). Clutch sizes differed among years and were lowest during the drought years. Raccoons (Procyon lotor) and striped skunks (Mephitis mephitis) were the major predators of nests. The percentage of all duck nests that were depredated varied among years and increased from 40% and 46% during the 2 wet years to 75% and 90% during the 2 drought years. The percentage of nests that were successful varied among years and were highest during the wet years. The yearly percentage of successful nests was negatively correlated with the abundance of all predators and positively correlated with snowfall because few skunks and raccoons survived the winter of 2023 with its heavy snowfall. Daily survival rates ( = 0.93), were similar among duck species, but varied among years; DSRs were lowest during the drought years (0.86 and 0.92) and highest during the wet years (0.96 for both years). Our results suggest that climate extremes will have an adverse impact on both the number of duck nests and the percentage of them that are successful.

Nest preference and laying duration traits to select against floor eggs in laying hens

BackgroundFloor eggs, which are defined as eggs that hens lay off-nest, are a major issue in cage-free layer poultry systems. They create additional work for farmers because they must be collected by hand. They are also usually soiled or broken, which results in economic losses. Nonetheless, knowledge about the genetics of nesting behavior is limited. The aim of this study was to estimate genetic parameters for traits related to nest preference for laying and to time spent in the nests used for laying (laying duration).MethodsTwo pure lines of laying hens were studied: 927 Rhode Island Red and 980 White Leghorn. Electronic nests were used to record the nesting behavior of these hens in floor pens from 24 to 64 weeks of age. Nest preference was studied based on the mean distance between nests used for laying and the percentage of nests used for laying. Laying duration was studied based on mean laying duration, mean duration in the nest before laying, and mean duration in the nest after laying. Genetic parameters were estimated for each line using a restricted maximum-likelihood method applied to a pedigree-based multi-trait animal model.ResultsEstimates of genetic parameters were similar for the two lines. Estimates of heritability ranged from 0.18 to 0.37 for nest preference traits and from 0.54 to 0.70 for laying duration traits. Estimates of genetic correlations of these traits with clutch number or mean oviposition time were favorable. Positive genetic correlations were estimated between nest preference and laying rate in the nests or nest acceptance for laying (+ 0.06 to + 0.37).ConclusionsThese results show that genetics influences traits related to nest preference and laying duration. Selecting hens that have no preference for particular nests and spend little time laying in the nests could help optimize nest use, reduce their occupation rate, and thus decrease the incidence of floor eggs in cage-free systems. Genetic correlations of these traits with other traits of interest related to hen welfare and egg quality have yet to be estimated.

Habitat-dependent breeding biology of the Blue Tit (Cyanistes caeruleus) across a continuous and heterogeneous Mediterranean woodland

Mediterranean woodland environments are characterised by high spatial and temporal heterogeneity, which means the inhabiting species face a wide variety of selective pressures. Species may respond differently to habitat heterogeneity and so distinct eco-evolutionary scenarios may be responsible for the inter-habitat variability in reproductive strategies observed in certain species. The inter-forest variability of some reproductive traits in passerines has been examined by comparing forest patches or separated fragments. However, there is still little information regarding how such highly mobile animals adjust their breeding performance across continuous and heterogeneous woodlands. Here we studied the reproductive performance of a population of Blue Tits (Cyanistes caeruleus) in an area of continuous Mediterranean woodland that included two mountain slopes and four different types of forest, ranging from deciduous oak forests to perennial non-oak forests. We studied the habitat heterogeneity and inter-forest phenotypic variation in terms of reproductive performance and adult and nestling biometry, besides also exploring the effects of ectoparasites on Blue Tit reproduction. Eggs were laid earliest in deciduous Pyrenean Oak (Quercus pyrenaica) forests, while clutch size and the number of fledglings were highest in the humid Pyrenean Oak forest, which had the greatest tree coverage and most humid climate, and lowest in the coniferous Scots Pine (Pinus sylvestris) forest. There were no inter-forest differences in hatching (percentage of nests with at least one egg hatched) and fledging (percentage of nests in which at least one nestling fledged) success. Similarly, there were no inter-forest differences in adult and nestling biometry, but adults that raised more fledglings had a lower body mass, while males whose females laid larger clutches had smaller tarsi. Most ectoparasites did not affect Blue Tit reproduction, although Culicoides had a negative impact on nestling body mass. These results suggest that Blue Tits can adjust their reproductive effort to the forest where they breed even across a very small spatial scale. Different eco-evolutionary scenarios, such as phenotypic plasticity or genetic structuring and local adaptation, might explain the phenotypic differentiation in the reproductive strategies observed over small areas in woodlands.

Status and Population Trends of Great Cormorant Phalacrocorax carbo sinensis Breeding in Greece

We analysed trends in the breeding population of Great Cormorants in Greece during the period 1988–2014 when at least 20 colonies were recorded. The number of colonies doubled over the study period reaching 14 in 2014 from seven in 1988. There was also a continuous increase in the number of nests: from 952 in 1988 to 9256 in 2014, presenting an annual change of +26.5% ± 0.05 (SD). Most of the colonies were situated in freshwater lakes, three in deltas and one on the seacoast. Nine colonies were mixed with other colonially nesting species (mostly from the Ardeidae family). Of the 14 colonies 11 were found in trees. Two colonies were situated on the ground, four in bushes, two on reed rhizome islets and one on cliff ledges. Five out of the 14 active colonies in 2014, comprising 87% of the total recorded nests, were in wetlands of low altitude (0–45 m a.s.l.). The rest were situated in mountainous wetlands at altitudes ranging from 235 to 853 m a.s.l. One colony, at Lake Kerkini, contained the majority of nests in Greece (6650, being 72% in 2014). The second largest colony, at Lake Volvi, had 900 nests, followed by the Greek part of Prespa with 625 nests (in three colonies) in 2014. The percentage of nests in newly established colonies increased after 2003, reaching its highest value (14%) in 2009. The reason for the growth in both colonies and nests over the years is attributed to the increasing availability of fish, the protection status of wetlands and the absence of disturbance. Particularly after 2002 the species increased in numbers and established colonies in new areas, which is probably related to the expanding breeding populations of the species in north-eastern European countries and a corresponding increase in wintering numbers in Greece. This needs further attention by monitoring and research.

Степной орёл в Республике Калмыкия (Россия): результаты исследования 2021 года

The article presents the results of the Steppe Eagle (Aquila nipalensis) study in the Republic of Kalmykia. 135 breeding territories of eagles were examined and 155 birds were observed during summer registrations and counts. The average distribution density of the occupied breeding territories in 2021 in the main part of the area was 2.15 (1.54–2.99)/100 km², in the zone of the large number of food resources – 5.72 (4.45–7.35)/100 km². The percentage of occupied breeding territories was 71%, and 43% of the occupied territories were successful. The number of nestlings in broods ranged from 1 to 3, averaging 1.81±0.69 per successful nest (n=43) and 0.73±0.95 per occupied nest (n=105). The percentage of nests with dead clutches and nestlings was high at all surveyed plots. The main diet of eagles during the breeding period included the Little Ground Squirrel (Spermophilus pygmaeus) (44%) and several additional prey items. A preliminary assessment of habitat suitability for the Steppe Eagle in terms of food conditions was carried out using GIS methods. Based on the registration data and clarification of the breeding range borders (47086.7 km²), the number of the Steppe Eagle in Kalmykia was re-estimated at 789 (587–1059) pairs. The signs indicating a negative trend in the population intensified: the percentage of immature birds in breeding pairs was 27%, the percentage of abandoned breeding territories was 19%. There is a consolidation of breeding groups in the population nucleus with a simultaneous decrease in breeding density at the periphery. Among the negative anthropogenic factors in 2021 there were the following: mass mortality on power lines, destruction of the food potential by the locals, disturbance during breeding, probable taking away of nestlings from nests.

Contrasting effects of egg size and appearance on egg recognition and rejection response by Oriental reed warblers.

BackgroundAmong potential hosts, the rejection of foreign eggs, which is a common and effective strategy to counter brood parasitism, depends on egg recognition. Multimodal and multicomponent recognition cues of brood parasitic eggs, which include both tactile (size, shape, and texture) and visual (size, shape, color, and maculation) cues, are potentially involved in the perception and discrimination of foreign eggs by hosts. An egg rejection experiment on the host with different types of model eggs can help to accurately assess the relative contribution of different components on egg recognition and constraints to rejection, in which videos can help identify the method of host rejection.MethodsHere, we assessed egg recognition and rejection responses by Oriental reed warblers (Acrocephalus orientalis), one of the most common hosts of common cuckoos (Cuculus canorus) which breed in eastern China. We designed six groups of model eggs for rejection experiments in which sensory cues included three grades of size and two categories of visual mimicry.ResultsOur experiments confirmed that the multimodal traits, which included variation in size, were significant predictors of egg rejection: We detected significantly higher rejection rates of mimetic spotted model eggs than of nonmimetic blue eggs. However, large model eggs did not yield higher rejection rates and, instead, these were less likely to be rejected and more likely to be deserted compared with smaller eggs. Further video‐recording data showed that there was no significant effect of egg size on the egg recognition rate (percentage of nests with evidence of egg pecking). No evidence that the egg appearance had an effect on the method of egg rejection (ejection or nest desertion) was found.ConclusionsOnly visual signals, such as color and maculation, contributed to the recognition of foreign eggs by Oriental reed warblers as recognizable clues, but not the egg size. The egg size had an impact on the type of egg rejection. It was less feasible for the warblers to eject large eggs and that is why they opted more often for desertion as the mean of model egg rejection. The significantly lower egg rejection rate of large eggs suggested that although some of them were recognized as foreign eggs, hosts failed to reject these eggs and finally the eggs were assumed to being accepted by the commonly used nest‐checking methods.

Factors influencing nesting success of the river lapwing, Vanellus duvaucelii (Lesson, 1826)

Nesting success is defined as the percentage of nests that have at least one chick that successfully fledges from them. In this regard, this study was conducted in the Gangetic plain of district Raebareli (Uttar Pradesh), India, to investigate nesting success, resolve factors affecting the probability of nest failure and identify the predominant nest predators of the river lapwing, Vanellus duvaucelii. The line transect method was adopted to count the nesting pairs, while nesting success was estimated by the Mayfield method. Results revealed that river lapwing nests were not homogeneously distributed at the study sites. The number of nesting pairs significantly diverged at various study sites in different years. Nesting success of river lapwings at all habitat types varied across the year of study from 67.9% in 2016, to 63.6% and 70.1% in 2017 and 2018, respectively. In all years, river lapwing nests on open, unvegetated river banks achieved significantly greater nesting success than those in crop fields. However, nest failure was mainly due to predation (55%) and farming activity (32%). Furthermore, trampling (6%) by domestic cattles such as cows and buffaloes, egg non-viability (4%), human disturbance (2%) and flooding (1%) were reported as other notable factors influencing nest failure. We also found reptiles, birds and mammals as predators of eggs in the study areas. The most common predators were crow, dog, fox and snake. There is little information regarding factors influencing nesting success of river lapwings particularly in India and therefore this study increases our knowledge of this globally near-threatened species. Developing greater understanding of the river lapwing could help us to formulate effective conservation measures for this species.

Island accessibility and distance from beach influence nesting success of Sooty FalconsFalco concolorin Oman

Colonial island‐breeding birds can be particularly vulnerable to anthropogenic disturbance, which can adversely affect their nesting success. We studied Sooty FalconsFalco concolorbreeding on 10 ground‐predator‐free islands in the Sea of Oman during 2007–2014 and evaluated spatio‐temporal trends in the number of breeding pairs occurring on the islands and the factors influencing nesting success. The number of breeding pairs on the islands declined during the study, due mostly to the decline on accessible islands; the rate of decline on islands accessible to humans was double that on inaccessible ones. The number of nests with one or more eggs declined during the study period, and the percentage of nests with eggs that produced one or more chicks showed an increasing trend over time. Sooty Falcon nests located farther away from beaches experienced a significantly higher probability of nesting success than those located closer to beaches. Our results suggest that the number of breeding Sooty Falcons on the islands of northern Oman is declining and that human disturbance may be a contributing factor; this probably mirrors the situation in other parts of the breeding range of this species.

Ring-Necked Pheasant Nest Success and Habitat Selection in Central South Dakota

Nesting habitat is a limiting factor for pheasant populations in much of the Great Plains. Pheasants select for and are generally most successful nesting in managed grasslands such as those established by the Conservation Reserve Program (CRP). Pheasants will nest in hay and cereal crop fields, but grain and forage harvest can reduce nesting success in those land-use types. An understanding of pheasant reproductive ecology in landscapes containing many potential nesting habitats is important for management recommendations. We used data from 123 ring-necked pheasant (Phasianus colchicus) nests during 2011–2012 to study nest-site selection and success in relation to land use type and landscape features in central South Dakota. Pheasants were 66% more likely to select CRP grassland than winter wheat for nest sites, and used spring wheat and other land-use types at a lower rate. Nest success was similar among land-use types, declined throughout the season, and declined in winter wheat as harvest progressed. Overall nest success (percentage of nests with ≥1 hatched egg) was 51% (95% CI: 40–58) and was the highest recorded in South Dakota. Our results validate past research that found high nest survival in landscapes with large patches of nesting habitat. Although harvest did destroy some re-nest attempts in winter wheat, nest success and nesting chronology was similar to CRP grassland. Our results suggest pheasant populations would benefit from establishment of large blocks of CRP grassland or cereal grains, especially winter wheat, in agricultural landscapes.

Use of noninvasive 'bug-eggs' to enable comparative inferences on genetic mating system with and without parental information: A study in a cattle egret colony.

Colonial waterbirds such as herons, egrets and spoonbills exhibit ecological characteristics that could have promoted the evolution of conspecific brood parasitism and extra-pair copulation. However, an adequate characterization of the genetic mating systems of this avian group has been hindered by the lack of samples of elusive candidate parents which precluded conducting conventional parentage allocation tests. Here, we investigate the genetic mating system of the invasive cattle egret using hematophagous insects contained in fake eggs to collect blood from incubating adults in a wild breeding colony. We tested a protocol with a previously unused Neotropical Triatominae, Panstrongylus megistus, obtained blood samples from males and females in 31 nests built on trees, drew blood from 89 nestlings at those nests, and genotyped all samples at 14 microsatellite loci, including six new species-specific loci. We comparatively addressed the performance of parentage allocation versus kinship classification of nestlings to infer the genetic mating system of cattle egrets. In line with previous behavioral observations, we found evidence in support of a non-monogamous genetic mating system, including extra-pair paternity (EPP) and conspecific brood parasitism (CBP). Parentage allocation tests detected a higher percentage of nests with alternative reproductive tactics (EPP: 61.7%; CBP: 64.5%) than the kinship classification method (EPP: 50.0%; CBP: 43.3%). Overall, these results indicate that rates of alternative reproductive tactics inferred in the absence of parental genetic information could be underestimated and should be interpreted with caution. This study highlights the importance of incorporating samples from candidate parents to adequately determine the genetic mating system of a species. We expand knowledge on the reproductive tactics of colonial waterbirds, contributing novel data on the genetic mating system of the cattle egret, valuable for the design of management strategies for this invasive bird.

Application of Best Subsets Regression on the risk classification for Spermophilus Dauricus Focus

To study the risk classification of animal plague in Spermophilus Dauricus Focus, using the Best Subsets Regression (BSR) model. Matlab, BSR and exponential smoothing were employed to develop and evaluate a model for risk classification as well as to forecast plague epidemics at the Spermophilus Dauricus Focus. Data was based upon the Inner Mongolia surveillance programs. This model involved 7 risk factors, including density of Spermophilus dauricus, percentage of hosts infested, host flea index, percentage of nests infested, nest flea index, percentage of runways infested, and runway flea index. Forecasting values of the classification model(CM)were calculated and grouped into 3 risk levels. Values that over 2/3 of the CM would indicate the existence of potential epidemics while those below 1/3 would indicate that there were no risk for epidemics but when values that were in between would indicate that there exist for high risk. Annually, during the observation period in the Inner Mongolia Spermophilus Dauricus Foci, the detection of Yersinia pestis gave a risk rating value of 1 which stood for existing epidemics, while nil detection rate generated a 'zero' value which representing the situation of non-epidemic. The overall plague epidemics forecasting surveillance programs in 2012 at the Spermophilus Dauricus Foci indicated that no active plague was observed. When the forecasting values became over 2/3, combinations of all the risk factors would achieve the consistency rates of 100%. When the forecasting values were below 1/3, combinations of at least the first 4 factors could also achieve the consistency rates of 100%. However, when the forecasting values fell in between, combinations of at least the first 4 factors would achieve the consistency rates of around 50%. Results from our study showed that plague would not be active to become epidemic, in 2012.

Consequences of urbanizing landscapes to reproductive performance of birds in remnant forests

In contrast to the well-documented changes in avian community structure in urbanizing areas, the demographic consequences of urbanization remain less understood. As such, we examined the extent to which an urbanizing landscape matrix affected avian reproductive performance in forests. From 2001 to 2011, we studied five songbird species in 19 forested sites in Ohio, USA and monitored 4264 natural nests to determine rates of daily nest survival and brood parasitism by brown-headed cowbirds (Molothrus ater). We also tracked the annual number of fledglings produced by color-banded pairs of two focal species, the synanthropic northern cardinal (Cardinalis cardinalis, n=974 breeding pairs between 2003 and 2011) and the urban-avoiding Acadian flycatcher (Empidonax virescens, n=350 breeding pairs between 2001 and 2011). Over the 10-year period, neither daily nest survival nor brood parasitism rates in remnant forests were consistently related to the amount of urbanization in the surrounding landscape matrix for focal species, with the sole exception of Acadian flycatcher for which the percentage of nests with brood parasitism increased with urbanization. Annual reproductive output of cardinals was comparable across the rural–urban gradient, but Acadian flycatchers produced fewer fledglings as urbanization increased. These findings demonstrate that urban-associated patterns of annual reproduction cannot necessarily be inferred from nest survival data alone. Moreover, we show that avian community changes are not the simple consequence of nest predation. Understanding ecological processes that operate within metropolitan areas is critical if we are to conserve biological diversity on our urbanizing planet.

Diversity and Abundance of Ectoparasitic Blow FliesProtocalliphora(Diptera: Calliphoridae) and theirNasonia(Hymenoptera: Pteromalidae) Parasitoids in Tree Swallow Nests within Agricultural Lands of Southern Québec, Canada

AbstractWe described the community composition of the ectoparasitic flies Protocalliphora Hough (Diptera: Calliphoridae) and their Nasonia (Ashmead) (Hymenoptera: Pteromalidae) parasitoids collected from tree swallow, Tachycineta bicolor (Vieillot), nests in southern Québec, Canada, in 2008 and 2009. The prevalence of nest infestation by Protocalliphora was 70.8% in 2008 and 34.6% in 2009. The average parasitic burden of Protocalliphora spp. was estimated at 5.53 (±5.61 SD) pupae per nestling for 2008 and 4.66 (±9.31 SD) pupae per nestling for 2009. The percentage of nests containing Protocalliphora pupae parasitized by Nasonia spp. was of 85.3% in 2008 and 67.2% in 2009. Three species of Protocalliphora were collected—Protocalliphora sialia Shannon & Dobroscky, Protocalliphora bennetti Whitworth, and Protocalliphora metallica (Townsend)—and two species of Nasonia, Nasonia vitripennis (Walker) and Nasonia giraulti Darling. This is the first record of P. bennetti and N. giraulti in the province of Québec. Our findings provide further evidence for observation made previously that altricial bird nests are more frequently and more heavily infested by blow flies in western than in eastern North America. Our data also suggest that more than a quarter of the tree swallow within the study area are exposed to high levels of ectoparasitism that could negatively affect their health.

Alien eggs in duck nests: brood parasitism or a help from Grandma?

Intraspecific brood parasitism (IBP) is a remarkable phenomenon by which parasitic females can increase their reproductive output by laying eggs in conspecific females' nests in addition to incubating eggs in their own nest. Kin selection could explain the tolerance, or even the selective advantage, of IBP, but different models of IBP based on game theory yield contradicting predictions. Our analyses of seven polymorphic autosomal microsatellites in two eider duck colonies indicate that relatedness between host and parasitizing females is significantly higher than the background relatedness within the colony. This result is unlikely to be a by-product of relatives nesting in close vicinity, as nest distance and genetic identity are not correlated. For eider females that had been ring-marked during the decades prior to our study, our analyses indicate that (i) the average age of parasitized females is higher than the age of nonparasitized females, (ii) the percentage of nests with alien eggs increases with the age of nesting females, (iii) the level of IBP increases with the host females' age, and (iv) the number of own eggs in the nest of parasitized females significantly decreases with age. IBP may allow those older females unable to produce as many eggs as they can incubate to gain indirect fitness without impairing their direct fitness: genetically related females specialize in their energy allocation, with young females producing more eggs than they can incubate and entrusting these to their older relatives. Intraspecific brood parasitism in ducks may constitute cooperation among generations of closely related females.

Egg Success, Hatching Success, and Nest-site Selection of Brown Pelicans, Gaillard Island, Alabama, USA

Abstract We investigated factors that affect nest-site selection, egg success, and hatching success of Brown Pelicans (Pelecanus occidentalis) on Gaillard Island, Alabama, USA, a man-made island in Mobile Bay. Vegetation density at differing heights, and temporal and spatial variables were considered in the analysis. Brown Pelicans arriving earliest chose sites that were open on the ground, but with a layer of vegetation between 1 and 2 m above the ground. Egg success was related to arrival date, density of the highest vegetation layer, density of nests in a given area, and percentage of nests on the ground. Brown pelicans that arrived earliest appeared to choose more optimal nest-sites and had greater egg and hatching success.

Estimating Nest Success: The Mayfield Method and an Alternative

Estimating Nest Success: The Mayfield Method and an Alternative

A fehér gólya (Ciconia ciconia) állomány vizsgálata Dél-Somogyban, az 1991-2000. években

In the course of 1991-2000, the author carried out a population survey of white stork in South Somogy county (1200 km2). 46 villages and 22 farms were regularly checked by years. During the examination the number of breeding pairs (Hpa) were about 99-102 and 143-148, so the density (StD) were 8.25-12.33 pairs/100 km2. There were the lowest the portion of successful breeding (HPm) (49.6%) in 1997, while the highest (83.3%) was in 1994. In 1996, 1994 and 2000, the total numbers of juveniles (JZG) were the highest. Between 1991-2000, the survey pointed out that 34.6% increasing in the percentage of nests.

Interannual and interspecific variation in intensity of the parasitic fly, Philornis downsi, in Darwin’s finches

An integrative approach to managing host–parasite interactions that threaten species communities will benefit from identifying variation in parasite impact across host species, and host–parasite responses to annual climatic variation. We examine interannual, inter- and intraspecific variation in Philornis downsi intensity – an introduced blood sucking fly that causes high fitness costs in Darwin’s finches on the Galápagos Islands. We sampled 131 nests of six finch species (with nestling survival ⩾6 days post-hatching) between 1998 and 2005 on Santa Cruz Island. P. downsi total (per nest) and mean (per nestling) intensity differed across species and years. The woodpecker finch ( Cactospiza pallida), and the large tree finch ( Camarhynchus psittacula) had the highest total parasite intensity. Both species had comparatively large adult body mass, and we found a positive association between adult body mass and total parasite intensity among nestlings. P. downsi total and mean intensity was highest during the El Niño year of 1998. Surprisingly, despite a threefold difference in rainfall across lowland and highland habitats in other than the El Niño year, there was no difference in parasite intensity per nest between habitats. However, species composition of hosts and intraspecific brood size vary across habitats. Highland nests with larger broods and lower mean (per nestling) parasite intensity had higher fledging success. There was no significant effect of total parasite intensity on fledging success for intraspecific analyses. The percentage of nests with nestling mortality in each habitat ranged between 40% and 100% for all six host species.

Nicarbazin OvoControl G Bait Reduces Hatchability of Eggs Laid by Resident Canada Geese in Oregon

Abstract: Expanding populations of resident Canada geese (Branta canadensis) are resulting in increased conflicts with humans. Nonlethal and humane means are needed for managing Canada goose flocks at a variety of sites, including golf courses, industrial parks, government sites, and city parks. Decreased egg production and hatching are side effects of nicarbazin, a veterinary drug used to treat coccidiosis in chickens. Capitalizing on these effects, we developed nicarbazin as a reproductive inhibitor for Canada geese and conducted a field efficacy study. We recruited study sites in 2002 and 2003. Following laboratory testing, we conducted a field efficacy trial of nicarbazin for reducing the hatchability of Canada goose eggs in spring 2004 in Oregon, USA. The study began in February 2004 at 10 sites in Oregon, with 2 control and 3 treated sites on each side of the Cascades. We fed bait daily to resident Canada geese for approximately 6 weeks. We located and monitored nests until hatching or ≥5 days beyond the expected hatching date to determine hatchability. We completed data collection in May 2004. Geese consumed 8,000 kg of bait, with 5,100 kg of OvoControl G® (Innolytics, LLC, Rancho Santa Fe, CA) 2,500‐ppm nicarbazin bait consumed among 6 treated sites and 2,900 kg of untreated bait consumed among 4 control sites. We monitored 63 nests at treated sites and 46 nests at control sites to determine hatching success of eggs. There was a 62% reduction in the percentage of nests with 100% hatchability at treated sites as compared to controls. There was a 93% increase in the percentage of nests at treated sites with 0% hatchability as compared to nests with no eggs hatching at control sites. Hatchability from treated sites versus control sites was reduced 36% (F = 5.72, P = 0.0622). We submitted results from this study to support Environmental Protection Agency registration of nicarbazin as a reproductive inhibitor for use in Canada geese. We have shown that treatment of resident Canada geese with OvoControl G 2,500‐ppm nicarbazin bait by licensed, trained applicators immediately prior to and during the breeding season can reduce hatchability of eggs laid by treated geese, thereby reducing recruitment of goslings into problem resident Canada goose populations.

Colony size, reproductive success, and colony choice in Cave Swallows Petrochelidon fulva

We investigated how annual reproductive success, as measured by the number of nestlings surviving to day 10 and the percentage of nests that were successful, varied with colony size of the Cave Swallow Petrochelidon fulva in south central Texas. We also studied whether Cave Swallows chose colonies, in part, on the basis of reproductive success at a site the previous year. Neither measure of reproductive success varied significantly with colony size for either first‐wave or second‐wave nestings. Mean clutch size per colony did not vary significantly with colony size. Mean nestling body mass, an index of parental foraging efficiency, was unrelated to colony size, except for broods of five, in which nestling mass declined significantly with colony size. Colony size was not significantly affected by reproductive success at the site the previous year, although sites with more successful nests during the first wave declined less in size during the second wave within the same season than did sites that had fewer successful first‐wave nests. Unlike the closely related Cliff Swallow Petrochelidon pyrrhonota, Cave Swallows did not use breeding performance of conspecifics in choosing nest‐sites, because they did not preferentially aggregate at sites that were the most successful the previous year. Coloniality in Cave Swallows did not appear to have a net negative effect on annual fitness, suggesting that colonial nesting was not solely a response to nest‐site limitation, but the benefits of breeding colonially (if any) were unclear.