Individual Nests Research Articles

Frequency of Nest Use by Golden Eagles in Southwestern Idaho

We studied nest use by Golden Eagles (Aquila chrysaetos) from 1966 to 2011 to assess nest reuse within territories, ascertain the length of time that elapses between uses of nests, and test the hypotheses that reproductive success and adult turnover influence nest switching. Golden Eagles used 454 nests in 66 territories and used individual nests 1 to 26 times during 45 continuous years of observation. Time between reuse ranged from 1 to 39 yr. Distances between nearest adjacent alternative nests within territories ranged between <1 and 1822 m, and distances between 90% of adjacent nests were <500 m. Of all nests used, 21% fell or disintegrated, and 31% were newly constructed during the study. Nest switching was not associated with the previous year's nesting success, but eagles tended to change nests after turnover of at least one member of the pair. Five of 42 nests used in 1971 and monitored continuously through 2011 were used only once and 21 were used >5 times. Two nests were unused for 21 and 27 yr after 1971 before being used every 1 to 3 yr thereafter. Eagles used 43% of the nests in series of consecutive years (range 3 to 20 consecutive nestings). Protecting unused nests for a proposed 10 yr after the last known use would not have protected 34% of all 300 nests that were reused during the study and 49% of 37 reused nests monitored consistently for 41 yr. The 102 nests that would not have received protection were in 56 of the 66 territories.Estudiamos el uso de nidos por parte de Aquila chrysaetos desde 1966 hasta 2011 para evaluar la reutilización de nidos dentro de territorios, determinar el lapso de tiempo que transcurre entre la utilización de nidos y probar la hipótesis de que el éxito reproductivo y el recambio de adultos influencian el cambio del nido. Las águilas utilizaron 454 nidos en 66 territorios y utilizaron nidos individuales de 1 a 26 veces durante 45 años continuos de observación. El tiempo transcurrido entre reutilizaciones varió de 1 a 39 años. Las distancias entre los nidos alternativos adyacentes más cercanos dentro de los territorios osciló entre <1 y 1822 m, y las distancias entre el 90% de los nidos adyacentes fueron de <500 m. De todos los nidos utilizados, el 21% se cayó o desintegró, mientras que el 31% fue construido desde cero durante el estudio. El cambio del nido no estuvo asociado con el éxito de nidificación del año anterior, pero las águilas tendieron a cambiar de nido después de un recambio de al menos uno de los miembros de la pareja. Cinco de 42 nidos utilizados en 1971 y monitoreados continuamente hasta el 2011 fueron ocupados sólo una vez y 21 fueron utilizados >5 veces. Dos nidos no fueron utilizados por 21 y 27 años después de 1971 para ser luego ocupados cada uno a tres años a partir de entonces. Las águilas utilizaron el 43% de los nidos en series de años consecutivos (rango de 3 a 20 nidadas consecutivas). La protección de nidos sin utilizar durante 10 años posteriores al último uso conocido no hubiera alcanzado un 34% del total de los 300 nidos que fueron reutilizados durante el estudio y 49% de los 37 nidos reutilizados monitoreados constantemente durante 41 años. Los 102 nidos que no hubieran recibido protección se ubicaron en 56 de los 66 territorios.

Structural Examination of the Dufour's Gland of the Solitary BeesOsmia lignariaandMegachile rotundata(Hymenoptera: Megachilidae)

AbstractThe Dufour's gland of two solitary cavity-nesting bees, Osmia lignaria Say and Megachile rotundata (F.) (Hymenoptera: Megachilidae), was examined with microscopy to determine the structure and arrangement of the gland in the sting apparatus. The appearance and relative size of the Dufour's gland of these two bee species are similar. Unlike the termination of the Dufour's gland at the base of the sting in the honey bee, Apis mellifera L. ( Apidae), the posterior portion of the Dufour's gland in these megachilids enters into the sting bulb along with the venom duct. Within the sting bulb, the Dufour's gland is ventral to and longer than the venom duct. The following evidential findings presented here and elsewhere are in support of the hypothesis that the Dufour's gland is the source of an individual nest recognition cue in these two bee species: 1 ) the presence of a duct and exit pore at the posterior end of the Dufour's gland that may release glandular secretions, 2) the location of thick, brushy metasomal setae and the setosa membrane that could be used to apply a secretion to a substrate, and 3) the observed dragging of the tip of the abdomen during nest-marking.

Clutch Size and Nest Survival of Cackling Geese in a Lesser Snow and Ross's Goose Colony

Clutch size and nest survival of Cackling Geese (Branta hutchinsii hutchinsii) nesting among light geese (Lesser Snow Geese (Chen caerulescens) and Ross's Geese (C. rossii;)) were examined at Karrak Lake, Nunavut, in Canada's central arctic, 1999–2009. Islands of Karrak Lake and adjacent Adventure Lake were selected by Cackling Geese for nesting instead of mainland habitat. Cackling Geese increasingly nested on islands during the study, while light goose nesting declined. Clutch size varied by year (range: 3.4–4.4 eggs), and declined with nest initiation date ( NID = -0.l77 (95% CI:-0.228,–0.126)). Nest survival during incubation varied among years (range: 8.6–88.2%), and was lowest during early and late incubation, although 95% CI of slope estimates with nest age included zero ( Age = 0.156 (95% CI -0.072, 0.383), A2 = -0.006, (95% CI -0.027, 0.014)). Nest survival declined with individual nest initiation date ( NID = -0.431 (95% CI: -0.680, -0.182)). There was little support for nest survival models that included individual covariates of synchrony with light geese or weather during incubation. A posteriori analysis revealed that annual nest survival was greater in warmer years with less wind ( YearWeather = 1.738 (95% CI: 1.272, 2.205)), but spring phenology, intraspecific synchrony, or abundance of Cackling or light geese were not important. Reduced access to island-nesting geese by terrestrial predators, and predator satiation from high densities of nesting light geese on the surrounding mainland may result in islands within light goose colonies that are productive nesting habitats for many avian species, particularly if islands themselves are sparsely inhabited by light geese.

A retrospective analysis of sea turtle nest depredation patterns

AbstractNest predation can significantly reduce hatchling recruitment in sea turtle populations. We examined 20 yr of data from Canaveral National Seashore, Florida, which has pristine and altered beaches. We used chi‐squared test to determine if secondary predation events were related to the nests' primary predation events, and proportional hazard regression analysis to determine the relative risk of individual nest predation. To determine if human beach use and nest predation risk were spatially or temporally linked, we ranked human beach use and examined predation frequency across all screened and marked nests. We found that once a nest has experienced predation it has an increased likelihood of experiencing a subsequent predation event when compared to other nests on the beach. Primary and multiple predation events occurred with greater frequency in limited beach use areas and with lowest frequency in moderate use areas. Predation risk decreased by an average of 29.5% from 2000 to 2008, relative to the initial year of study. Nests deposited mid‐season were 9.8% more likely to be predated than early or late season nests. We conclude that where anti‐nest predator management efforts are required but restricted (e.g., by funds, available personnel, or multiple management goals) resources should be concentrated to protect mid‐season nests and those in limited access areas, if enhancing hatchling numbers is a management goal. © 2012 The Wildlife Society.

Indirect estimates of breeding and natal philopatry in an obligate avian brood parasite

In theory, obligate brood parasitic birds are freed from several of the temporal and spatial constraints of parental care for dependent young. Yet, similar to parental bird species, adults in several avian brood parasites show a territorial spacing system while breeding, including site fidelity within and across years. Banding-based capture and sighting studies are also suggestive of non-parasite-like lower levels of natal philopatry in avian brood parasites. We analyzed the potential correlation of physical distance with genetic structure of a Brown-headed Cowbird Molothrus ater population, sampling parasitic chicks from nests across different temporal and spatial scales of its common host, the Eastern Phoebe Sayornis phoebe, near Ithaca, New York, USA. In support of extensive breeding but not historical patterns of natal philopatry, we detected no significant covariation of genetic similarity by distance of nestling parasites at the scale beyond that of individual host nest sites. These results contribute towards a baseline for future behavioral and genetic comparisons of whether and how parasitic versus parental reproductive strategies impact patterns of avian population genetic structure across space and time.

Response of red‐cockaded woodpeckers to military training operations

Response of red‐cockaded woodpeckers to military training operations

VOCAL REPERTOIRE OF WILD BREEDING ORANGE-WINGED PARROTS AMAZONA AMAZONICA IN AMAZONIA

ABSTRACT The vocal repertoire of Amazona amazonica during its breeding season has been recorded from wild individuals in Santa Bárbara do Pará, Pará State, Brazil. At individual nests, we continuously recorded vocalizations and behaviour for four hours in the early morning and three hours in the late afternoon, three times a week throughout the breeding season. We identified nine vocalizations that we classified in three behavioural categories: (1) Flight call—emitted when parrots arrive in the nest area; (2) Perched contact calls—two different vocalizations, one of them related to feeding, were emitted when the pair was perched in the nest area and interacted socially between themselves or with other individuals; (3) Aggressive calls—emitted when birds were in a dangerous situation, i.e. alarm (three types of calls), agonistic contact and distress calls (two types of call). The Orange-winged Parrot is a highly social species and the complexity of its social interactions is reflected in the diversity of its vocal repertoire.

Latitudinal Variation in Reproductive Strategies by the Migratory Louisiana Waterthrush

Abstract. We evaluated hypotheses that seek to explain breeding strategies of the Louisiana Waterthrush (Parkesia motacilla) that vary across a latitudinal gradient. On the basis of data from 418 nests of color-banded individuals in southwestern Pennsylvania and 700 km south in the Georgia Piedmont, we found that clutch size in replacement nests and probability of renesting were significantly greater in Pennsylvania (clutch size 4.4; renesting probability 0.66) than in Georgia (clutch size 3.8; renesting probability 0.54). Contrasts of the remaining measures of breeding were not statistically significant, and, in particular, mean daily nest survival in the two study areas was nearly identical (0.974 in Pennsylvania; 0.975 in Georgia). An individual-based model of fecundity (i.e., number of fledged young per adult female), predicted that approximately half of the females in both Pennsylvania and Georgia fledge at least one young, and mean values for fecundity in Pennsylvania and Georgia were 2.28 and 1.91,...

Egg size matching by an intraspecific brood parasite

Avian brood parasitism provides an ideal system with which to understand animal recognition and its affect on fitness. This phenomenon of laying eggs in the nests of other individuals has classically been framed from the perspective of interspecific brood parasitism and host recognition of parasitic eggs. Few examples exist of strategies adopted by intraspecific brood parasites to maximize success of parasitic eggs. Intraspecific brood parasitism within precocial birds can be a risky strategy in that hatch synchrony is essential to reproductive success. Given that egg size is positively correlated with incubation time, parasitic birds would benefit by recognizing and selecting hosts with a similar egg size. Intraspecific brood parasitism is an alternative reproductive strategy in black brant (Branta bernicla nigricans), a colonial nesting goose with precocial young. Based on a randomization test, parasitic eggs in this study differed less in size from eggs in their host's nests than did random eggs placed in random nests. Parasitic eggs were remarkably similar in size to hosts’ eggs, differing by <2% of volume on average from host eggs, whereas randomly paired eggs in random nests differed by nearly 8%. The precision with which parasitic brant match the egg size of hosts in our study supports our hypothesis that brant match egg size of hosts, thereby maximizing hatching success of their parasitic eggs.

Attraction to old nest cues during nest selection by the solitary bee Megachile rotundata (Hymenoptera: Megachilidae)

SummaryThe alfalfa leafcutting bee, Megachile rotundata F. (Hymenoptera: Megachilidae), is an important pollinator for the commercial production of alfalfa seed. Poor nest establishment is, however, an ongoing problem for bee managers. Megachile rotundata are solitary yet gregarious bees that nest in pre-existing cavities and are attracted to previously used nests. Nest cells contain several components that may serve as cues for nesting females. In the current study, we sought to: 1. determine if there is a preference for cells that previously held male or female conspecific bees; 2. verify attraction to conspecific whole nest cells; and 3. determine which individual nest components of a cell are attractive to nesting females. In a series of cage and open field experiments, M. rotundata females were allowed to initiate nests in blocks containing whole cells or individual cell components from old nests. Statistical analyses of results verified the attraction to conspecific nest cells, with no preference for male or female cells. Females were equally attracted to whole cells from conspecifics and from another megachilid bee, Osmia lignaria. In field cages, females were equally attracted to all cell components, but preferred some cell components over others in open field experiments. These results provide a foundation for future studies to identify potential chemical lures to aid in the retention of bee populations at commercial nest sites.

Influence of habitat on nest location and reproductive output of Montagu’s Harriers breeding in natural vegetation

We examined distribution and breeding success of semi-colonial Montagu’s Harriers (Circus pygargus) in relation to habitat in Castellon province (eastern Spain). Breeding areas used by harriers at a 1-km2 scale were characterised by having intermediate percentages of scrub cover, their nesting habitat, and also had intermediate coverage of herbaceous crops and non-irrigated orchards. Out of all habitat variables considered, only the percentage of herbaceous crops within 500 m from individual nests had a positive and significant effect on breeding output of the species, suggesting that this habitat may be efficiently used by harriers to forage. Breeding output was also related to laying date and number of breeding neighbours within 500 m around nests, with pairs laying later and having a higher number of breeding neighbours showing lower fledged brood sizes. Number of neighbours (but not laying date) was positively related to scrub cover within 500 m and to cover of herbaceous crops within 2,000 m. Conservation actions for Montagu’s Harrier in the study area should be aimed at preserving areas of scrub with nearby presence of herbaceous crops or natural grasslands. However, habitat improvement for semi-colonial species such as Montagu’s Harrier may not result in a change of species distribution area, and good habitat areas may remain unoccupied, as social factors like presence of conspecifics play an important role in breeding area selection for these species.

Causes and consequences of fine-scale breeding dispersal in a female-philopatric species

The potentially confounded effects of factors affecting breeding dispersal have rarely been simultaneously examined. The consequences of breeding dispersal are even less studied, presenting a paradox: breeding dispersal seldom seems to improve breeding success, despite its presumed adaptiveness. We studied the causes and consequences of breeding dispersal in female-philopatric eiders (Somateria mollissima) in relation to the spatiotemporal predictability of nest success. Previous nest fate, breeding experience, and breeding density simultaneously affected breeding dispersal. Dispersal distances were longer among inexperienced breeders and after failed breeding. Individual dispersal distances decreased with increasing nest-site-specific breeding density, whereas island-specific nesting success peaked at intermediate densities. The fate of neighbouring nests ('public information') did not influence dispersal. Breeding dispersal was unrelated to subsequent hatching success, controlling for individual quality (body condition, breeding experience, previous nest fate), while it delayed hatch date, which is likely to impair reproductive success. This delay may result from the loss of acquired information of local breeding conditions, prolonging nest prospecting and establishment, also helping explain why breeding dispersal did not increase at high breeding densities, despite a potential reduction in nesting success. In long-lived species, however, dispersal-induced reductions in reproductive output in one season could be offset by improved parental survival prospects. Careful nest prospecting may be profitable, because overall nest success had a strong island-specific component but showed weak temporal variation, and successive individual nest fates were predictable between years. Once a safe nest site is found, females may breed at the same place successfully for many years.

Offspring Size and Sex Ratio Variation in a Feral Population of Alfalfa Leafcutting Bees (Hymenoptera: Megachilidae)

AbstractThe alfalfa leafcutting bee, Megachile rotundata (F.) (Hymenoptera: Megachilidae), is widely used in western North America to enhance pollination of alfalfa, Medicago sativa L., grown for seed production. Feral populations have been documented but have been little-studied, We used trap-nests of a wide range of diameters (3–9 mm) to study a feral population at a wildflower seed farm in Montana. Adult females accepted all hole sizes but tended to provision nest tunnels of smaller diameters (3–4 mm) than those provided in managed populations (5–7 mm). Progeny, especially females, from intermediate- and large-diameter nests averaged larger body size that those in the two smallest nest-diameter classes. Offspring were often larger in nests with greater numbers of offspring, indicating that there was no trade-off between offspring size and number within nests. Individual nests tended to contain a relatively small range of progeny sizes and those sizes tended to vary among nests of the same diameter. Previous studies of M. rotundata indicate that heritability of body size is low, most offspring within nests are full siblings, and variation in offspring size is due to variation in the amount of provision provided by mothers. Thus, the fact that body size varied among families probably related to variation in provisioning capabilities among females. We also found evidence that offspring size varied spatially but that seasonal trends in offspring size were weak. Sex ratio varied among different nest sizes, but only the smallest and largest nests produced biased ratios. Sex ratios were less male-biased than in commercially managed populations of M. rotundata.

Winter severity and phenology of spring emergence from the nest in freshwater turtles

Although many species of freshwater turtles emigrate to water soon after hatching, the offspring of some species overwinter on land and move to aquatic habitats in the following spring. Timing of emigration can affect the hatchlings' fitness, but the factors underlying phenology of nest emergence are incompletely understood. We tested the supposition that cold stress imposed during hibernation can influence the timing of nest emergence in three species of turtles in the central USA. In each year of the 6-year study, Chrysemys picta emerged in late March and early April and, on average, these hatchlings left their nests 2 weeks earlier than those of Graptemys geographica and 4 weeks earlier than those of Trachemys scripta. Emergence of conspecific hatchlings from different nests usually occurred over 3-7 weeks, but in some years lasted several additional weeks. Relatively few nests had siblings that emerged on the same day (i.e., synchronously); complete emergence of the typical sibling group required 1 to 2 weeks. In winter, subzero cold occurred with regularity in the nests of all species, though C. picta experienced the lowest temperatures owing to their shallower nests. However, for no species did emergence date or length of the emergence period correlate with winter minimum temperature and, at the level of the individual nest, neither did emergence synchrony or duration. Despite encountering lower temperatures, hatchlings of C. picta emigrated from their nests before those of sympatric species, suggesting that the fitness benefits of early emergence may lead to the improvement of cold-hardiness adaptations in northern populations of turtles.

Nest box use by woodland dormice (Graphiurus murinus): the influence of life cycle and nest box placement

The use of nest boxes by the woodland dormouse, Graphiurus murinus, was investigated over a 13-month period in a riverine forest of the Great Fish River Reserve, South Africa. We predicted that some characteristics of nest box placement would affect nest box use and that the seasonal pattern of nest box use would be linked to the species' life cycle and physiological and socioecological characteristics. Generalized linear models indicated that the time since nest box installation and nest box height above ground positively affected the frequency and intensity of nest box use. Male and female dormice, as well as adults and juveniles, did not differ in the number of nest boxes used and equally occupied individual nest boxes. The percentage of nest boxes used peaked during spring and summer (breeding period) and dropped during winter (hibernation). However, whereas significantly more males were caught during the mating season (spring), the number of females occupying nest boxes was constant during the year. As female dormice successfully bred in the nest boxes, the observed sexual patterns suggest that (artificial) nest sites represent an important resource for females, whereas females seem to constitute the main resource for males, as predicted by the socioecological model.

Short-term demographic response of an old forest specialist to experimental selection harvesting

The brown creeper (Certhia americana) was recently identified as one of the forest bird species most sensitive to partial harvesting in North America. However, the processes underlying this sensitivity are poorly known. In this study, we quantified the immediate, post-treatment demographic response of this species to experimental selection harvesting in plots of northern hardwood forest in northwestern New Brunswick, Canada. We mapped individual detections and nest locations in 5 pairs (1 control and 1 treatment) of 25-ha plots in the first 2 y after single-tree selection harvesting. Linear mixed models with site and landscape context as random effects showed a significant negative effect of treatment on nest density and seasonal reproductive success. The density of large-diameter trees (≥ 30 cm dbh) was significantly lower in treated plots than in controls (mean: 77 versus 112 stems-ha−1), whereas the density of potential nesting substrates (snags with peeling bark) did not decrease significantly following treatment. Hence, the density of suitable foraging substrates may represent a limiting factor for both nest density and reproductive success, and partial harvesting may not be compatible with the persistence of breeding populations of brown creeper. Patches of untreated forest should be maintained in managed forest landscapes at all times for this and other taxa requiring old forest conditions.

Nest groups of wild bonobos at Wamba: selection of vegetation and tree species and relationships between nest group size and party size

We examined the location of nest groups, spatial distribution of nests within a nest group, and attributes of individual nests of wild bonobos at Wamba, Democratic Republic of Congo. We also examined the seasonal factors influencing nesting behavior and compared the nest group size with the 1 hr party size during daytime. We defined a nest group to be a cluster of nests that were built in the same evening and found within 30 m from the other nearest nest. Examination of the largest gap within a nest group suggested that 30 m was an acceptable cutoff value. Monthly rainfall or fruit abundance did not significantly influence the monthly mean nest group size. Nests were built in the swamp forest for as many as 13% observation days, suggesting the need for reevaluation of the use of swamp forest by bonobos. The use of swamp forest was influenced not by seasonal rainfall or fruit abundance, but by the fruiting of specific species. Preferred tree species for building nests accounted for 19.8% of standing trees, which suggested that the selection of sleeping sites was not largely restricted by the distribution of specific species. The mean 1 hr party size was almost identical through the day and was similar to the mean nest group size. Parties of bonobos sometimes split into smaller nest groups, especially when feeding on non-preferred fruits during fruit scarcity. By contrast, when feeding on preferred fruits while ranging in large parties, they often aggregated to form even larger nest groups. When sleeping in small- or middle-sized nest groups, they tended to aggregate the next morning. These tendencies may reflect the gregarious nature of bonobos who prefer to range or sleep together as far as circumstances allow.

Polychlorinated biphenyls, dioxins, furans, and organochlorine pesticides in belted kingfisher eggs from the upper Hudson River basin, New York, USA

Nesting belted kingfishers (hereafter kingfishers, Ceryle alcyon) were studied on the Hudson River near Fort Edward south to New Baltimore (NY, USA) and three nearby river drainages in 2004. Concentrations of 28 organochlorine pesticides, 160 polychlorinated biphenyl (PCB) congeners, and 17 dioxin and furan (PCDD-F) congeners were quantified in kingfisher eggs. The pattern of organochlorine pesticides and PCDD-F congeners did not differ significantly between 14 eggs collected from individual nests on the Hudson River and five eggs similarly collected on three other nearby rivers. In contrast, the pattern of PCB congeners in eggs collected on the Hudson River differed significantly from the other rivers. The differences in patterns of PCB congeners were associated with a higher representation of lower-numbered congeners on the Hudson River than the other rivers. The higher prevalence of the lower-numbered congeners and lower prevalence of the higher-numbered congeners is consistent with Aroclor 1016 and 1242 being the source of the PCBs on the Hudson River. Concentrations in a sample egg collected at each nest were compared to nest survival and egg success (the proportion of eggs hatching in a clutch if at least one egg hatched) of the remaining eggs in the clutch. Models that predicted nest survival and egg success as functions of contaminant levels were poorly distinguished from models that presumed no such associations. Small sample sizes could have contributed to the inability to distinguish among contaminant and no toxicant models. However, we cannot rule out the possibility that contaminant concentrations on the Hudson River were not sufficiently high to demonstrate a relationship between contaminant concentrations and reproductive success in kingfishers.

Repeatability of nest predation in passerines depends on predator species and time scale

It has been proposed that some specific locations of bird's nests have higher intrinsic chances of being depredated than other locations. This predicts that fates of consecutive nesting attempts at the same site should be repeatable. We used 20 pairs of old thrush nests to simulate repeated nesting attempts at the same sites, both within and between breeding seasons (n =40 sites x 2 trials x 2 years = 160). Each nest was monitored by a camera to record multiple predation events and to identify predators. Predation by all predator species was repeatable during a 15-day trial. Predation by principal predators (jay Garrulus glandarius, marten Martes martes/foina) and total predation (all species combined) was not correlated within pairs of simultaneously exposed nests or within samples of nests from particular study plot, and not repeatable for individual nests between-trials or between-years. These findings suggest short-term effect of predator memory causing revisitation of previously depredated nests during a current nesting trial (all predators); do not support an effect of nest site features on multiple nest discoveries and/or an effect of nest location on repeated random encounters with the same nest (principal predators). Long-term repeatability and correlation within pairs of simultaneously exposed nests was detectable only in occasional predators (great spotted woodpecker Dendrocopos major, possibly also squirrel Sciurus vulgaris), which suggests effect of nest location combined with site fidelity and individual foraging specialization of these predators. We conclude that repeatability of nest predation depends on the time scale considered and the local predator community. We caution against spurious findings of repeatable nest predation resulting simply from statistical properties of correlation in binary data (nest fates).

Red Imported Fire Ants Can Decrease Songbird Nest Survival

Invasive species are often implicated in population declines of native species because of predation. The red imported fire ant (Solenopsis invicta) has been documented to prey on songbird nests. We conducted a replicated manipulative experiment to determine the decrease in nest survival caused by S. invicta. In 2006 and 2007 we monitored 71 nests, 44 of the White-eyed Vireo (Vireo griseus) and 27 of the Black-capped Vireo (V. atricapilla), in nine patches of 36–103 ha each in central Texas. We prevented S. invicta from preying on nests by applying insect-specific chemical and physical barriers at individual nests. Excluding S. invicta increased nest survival from 10% to 31% for the White-eyed Vireo and from 7% to 13% for the Black-capped Vireo. Our results suggest the decrease in nest survival of songbirds susceptible to predation by S. invicta may be substantial in the areas this ant occupies.