Nest Predation Rates Research Articles

Adaptation and Latitudinal Gradients in Species Interactions: Nest Predation in Birds.

AbstractAre biotic interactions stronger in the tropics? Here, we investigate nest predation in birds, a canonical example of a strong tropical biotic interaction. Counter to expectations, daily rates of nest predation vary minimally with latitude. However, life-history traits that influence nest predation have diverged between latitudes. For example, tropical species have evolved a longer average nesting period, which is associated with reduced rates of nest attendance by parents. Daily nest mortality declines with nesting period length within regions, but tropical species have a higher intercept. Consequently, for the same nesting period length, tropical species experience higher daily nest predation rates than temperate species. The implication of this analysis is that the evolved difference in nesting period length between latitudes produces a flatter latitudinal gradient in daily nest predation than would otherwise be predicted. We propose that adaptation may frequently dampen geographic patterns in interaction rates.

Threat recognition and response in an avian brood-parasite host from New Caledonia

AbstractNest predation and avian brood parasitism are the main sources of nest failure in many passerine birds. Large predators threaten both brood and parents, whereas brood parasites pose only a danger to eggs or nestlings. The fan-tailed gerygone Gerygone flavolateralis from New Caledonia is subjected to high rates of nest predation by the New Caledonian crow Corvus moneduloides (responsible for about 20–40% of predation) and moderate rates of brood parasitism by the shining bronze-cuckoo Chalcites lucidus (parasitizing about 18% of nests), which also depredates nests that are too advanced for parasitism (13% of nests). To test if fan-tailed gerygones are able to discriminate predators from brood parasites, we presented 3 bird models at active gerygone nests: a brood parasite/small nest predator (shining bronze-cuckoo), a large nest predator (crow), and a small non-native bird (common chaffinch Fringilla coelebs), which is unknown to the gerygone, as a control. We assessed the response of adult gerygones to the presentation of each model by measuring the minimum approach distance, number of alarm calls, number of attacks, and time to first nest visit after the presentation (latency). Adult gerygones often attacked the cuckoo, approached but never attacked the chaffinch and always avoided the crow. Latency was shorter after an attack response and during brooding, but similar among models. We did not find any link between the cuckoo model presentation and later ejection of cuckoo nestlings. We conclude that adult fan-tailed gerygones discriminate between different models and respond accordingly to the level of threat, but do not show awareness of parasitism risk and increase of nestling ejection rates following exposure to the cuckoo model.

Bright coloration of male blue manakin is not connected to higher rates of nest predation

Nest predation is a determinant factor for the success of birds breeding especially for tropical species. However, it is not clear whether parental color plumage can be used as a visual cue for predators to locate nests. Using 3D-printed models, we tested if the color of the parent’s decoy can influence the predation of artificial birds’ nests. The models were painted with male and female blue manakin (Chiroxiphia caudata) color patterns. This is a small sexual dimorphic passerine, where the male is highly ornamented (conspicuous pattern) while the female shows a matte green color (cryptic pattern). Nest attendance is fully provided by females. We did not find evidence that predation rates differ among treatments (male vs. female coloration), even when controlling the effect of local vegetation density and canopy openness. Our findings do not corroborate recent studies that test similar ideas that used models of large body size birds in open habitats. In conclusion, we suggest that the blue manakin color patterns do not influence the probability of adults to be detected by predators. At natural nests, we expected that other cues (e.g., olfactory) should be more effective for the localization of blue manakin nest in Neotropical forests.

Development syndromes in New World temperate and tropical songbirds.

We studied avian development in 49 to 153 species of temperate and tropical New World passerine birds to determine how growth rates, and incubation and nestling periods, varied in relation to other life-history traits. We collected growth data and generated unbiased mass and tarsus growth rate estimates (mass n = 92 species, tarsus n = 49 species), and measured incubation period (n = 151) and nestling period (n = 153), which we analyzed with respect to region, egg mass, adult mass, clutch size, parental care type, nest type, daily nest predation rate (DMR), and nest height. We investigated covariation of life-history and natural-history attributes with the four development traits after controlling for phylogeny. Species in our lowland tropical sample grew 20% (incubation period), 25% (mass growth rate), and 26% (tarsus growth rate) more slowly than in our temperate sample. Nestling period did not vary with respect to latitude, which suggests that tropical songbirds fledge in a less well-developed state than temperate species. Suboscine species typically exhibited slower embryonic and post-embryonic growth than oscine passerines regardless of their breeding region. This pattern of slow development in tropical species could reflect phylogenetic effects based on unknown physiological attributes. Time-dependent nest mortality was unrelated to nestling mass growth rate, tarsus growth rate, and incubation period, but was significantly associated with nestling period. This suggests that nest predation, the predominant cause of nest loss in songbirds, does not exert strong selection on physiologically constrained traits, such as embryonic and post-embryonic growth, among our samples of temperate and lowland tropical songbird species. Nestling period, which is evolutionarily more labile than growth rate, was significantly shorter in birds exposed to higher rates of nest loss and nesting at lower heights, among other traits. Differences in life-history variation across latitudes provide insight into how unique ecological characteristics of each region influence physiological processes of passerines, and thus, how they can shape the evolution of life histories. While development traits clearly vary with respect to latitude, trait distributions overlap broadly. Life-history and natural history associations differ for each development trait, which suggests that unique selective pressures or constraints influence the evolution of each trait.

Research activity does not affect nest predation rates of the Silver-throated Tit, a passerine bird building domed\xa0nests

BackgroundResearch activities have often been thought to potentially influence avian nesting success by increasing nest predation rates. Although recent studies of species building open nests and cavity nests suggest that research disturbance does not generally induce nest predation, whether it is also the case in species building domed-nests remains unknown. In birds, domed-nest species exist in about half of the passerine families, and research disturbance to the domed nests may differ from that to the nests of other types for their different nest structures.MethodsWe investigated if research activities affected nest predation rate by analyzing the relationships of the daily nest survival rate with the research activities at the egg and nestling stages of a domed-nest species, the Silver-throated Tit (Aegithalos glaucogularis).ResultsOur results showed that nest daily survival rate was significantly affected by the laying date and nest age during the egg stage, and by the hatching date only during the nestling stage. By contrast, there were no significant effects of research activities, in terms of visiting nests and filming nests, on the nest survival of the Silver-throated Tit at both the egg and nestling stages.ConclusionsOur results coincide with the findings in species building other types of nests that research activities do not always have negative effects on avian nesting success.

Landscape and habitat affect frequency of artificial duck nest predation by native species, but not by an alien predator

Annual Finnish breeding duck surveys over the last 30 years show declining abundance among several species and greater declines on eutrophic waters than oligotrophic lakes. It has been suggested that habitat-related differences in the rate of increase in predation pressure is a potential explanation for contrasting duck population trajectories between habitats. We assessed potential duck nest predation risk and predator presence in various duck breeding habitats in Finland and Denmark by monitoring 333 artificial duck nests with wildlife cameras during 2017–2019. Predation rates differed between landscapes and habitats: nest predation rate and predator diversity were lowest in forested and highest in agricultural landscapes. Forest nests further from water bodies survived better than nests around shorelines of permanent lakes. Of the 16 different predator species detected, the most common were Eurasian magpie (Picapica), hooded crow (Corvus corone) and raccoon dog (Nyctereutes procyonoides). While predation by specific native predator species was typically associated with particular habitats and landscapes, the alien raccoon dog appeared to be a true habitat generalist, ubiquitous and common across all habitats and landscapes. Based on these results, the higher duck nest predation pressure along shorelines, especially in agricultural landscape lakes, due to increased diversity and abundance within the predator community, may contribute to the declining population trends of ducks.

Fight or flight: Geographic variation in antipredator defenses by cinereous tits

In the face of death from predation, parent birds have to choose between prioritizing current versus future reproduction. Previous studies have shown that when exposed to predation risk, birds breeding in the tropics prioritize their own safety, whereas birds breeding at high latitudes prioritize the safety of future generations. However, this phenomenon has rarely been investigated among populations within a single bird species. Here, we studied the anti-predation behavior of female birds in response to a human observer of four cinereous tit (Parus cinereus) populations during their incubation period across different latitudes in China. When confronted with nest predation risk induced by the presence of a human, the probability of escape by cinereous tits decreased with increasing latitude, that is, the proportion of female birds that escaped from the nest was significantly larger in southern than in northern populations. For female birds that did not leave the nest, the proportion of individuals who produced a hissing call for nest defense was significantly lower in the southern than in the northern populations. In addition, nest defense behaviours were unrelated to nest predation rates, and clutch size in the southern cinereous tit populations was significantly smaller than that in the northern population, it was, therefore, likely that nest defense behaviours were related to clutch size. The present study confirms within a single species that under predation risk, female birds in the tropics prioritize future over current reproduction, while the birds breeding at high latitudes do the opposite.

Breeding biology of the Mountain Wren-Babbler (Gypsophila crassus)

Life history theory in ornithology has been mostly based on temperate birds in part because a relative paucity of biological data has been described for tropical species. Expanding our knowledge about life histories of tropical birds can help us to better understand global trends in life history strategies. To aid in this endeavor, we studied Mountain Wren-Babblers (Gypsophila crassus) breeding in Malaysian Borneo from 2009 to 2017. Relatively small (mean = 28.8 g), dark brown birds, they were cooperative breeders and foraged and cared for the nest in groups of typically 4 or 5 birds. We located 145 nests, which were globular and partially domed (91.8 mm mean opening height accounted for half of 180.7 mm total mean nest height), constructed from fern fronds on the outside and dead leaves on the inside, and most often placed on banks. Brooding attentiveness decreased with nestling age and was rare after day 7 once they began growing their primary feathers. Provisioning rate slightly increased with nestling age. Nestling growth rate constants were typical of many tropical birds, asymptoting a few days prior to fledging. Predation accounted for nearly all nest failures (87 of 88), with a daily nest predation rate for the total nesting period of 0.056 and nest success decreasing with elevation. Daily predation rate was highest during lay (0.117) and lowest during incubation (0.046). We compared these results with related species to identify potential explanations for the trends we described. The most notable result from these comparisons was that Mountain Wren-Babblers have a long incubation period (23.5 d) and adults only incubate for a small part of the day. This anomalous behavior emphasizes the importance of understanding the great variation in tropical life history strategies to ultimately improve life history theory.

Revisiting an old question: Which predators eat eggs of ground-nesting birds in farmland landscapes?

Nest predation is a major cause of reproductive failure in birds, but predator identity often remains unknown. Additionally, although corvids are considered major nest predators in farmland landscapes, whether breeders or floaters are involved remains contentious. In this study, we aimed to identify nest predators using artificial nests, and test whether territorial or non-breeders carrion crow (Corvus corone) and Eurasian magpie (Pica pica) were most likely involved. We set up an experiment with artificial ground nests (n = 1429) in farmland landscapes of western France, and assessed how different combinations of egg size and egg material (small plasticine egg, large plasticine egg, quail and natural hen eggs) might influence predation rates and predator species involved. Nest predators were identified using remotely triggered cameras and marks left in plasticine eggs. Corvids were by far the predators most involved (almost 80% of all predation events), independent of egg type. Carrion crows alone were involved in 60% of cases. Probability of predation increased with egg size, and predation rate was higher for natural than for artificial eggs, suggesting that, in addition to egg size, predators might perceive plasticine and natural eggs differently. Predation rates of artificial nests by corvids were related significantly to corvid abundance, and far more to breeder than floater abundances, for both carrion crows and magpies. This study emphasizes the importance of identifying predators at species level, and considering their social status when assessing corvid abundance impact on prey population dynamics. Combining camera traps and plasticine eggs can achieve this objective. Given the high predation rate by carrion crows, a better understanding of landscape-mediated changes in predator diet seems mandatory to design mitigation schemes able to confront ecological challenges raised by generalist predators.

Nest Predation in the African Blue Tit, Cyanistes teneriffae (Aves, Paridae), Using Nest-Boxes and Artificial Nests

Predation on breeding blue tit populations in north-eastern Algeria has been studied in nest boxes during a five years fieldwork (2003-2007) in cork oak forests. Nest boxes were placed each year in Brabtia plain forest in El Kala National Park. Results have shown that mean nest predation rate is 51.74%. Six patterns of nest predation have been described and five predators are probably involved: Common Genet, Great Spotted Woodpecker, Ocellated Lizard, Ants and Rodents. Genet is the major predator on tit nests. Mean predation rates on egg and nestling stages are similar. Artificial nests and natural nests had similar predation rates. Major predators on artificial nests were lizards and Rodents.

Risk-taking behavior of bull-headed shrikes that recently colonized islands

Individuals which have invaded urbanized environments are reported to engage in riskier behaviors, possibly influenced by the scarcity of predators in urbanized areas. Here, we studied the risk-taking behavior of birds which had invaded a new natural environment, rather than an artificial urban environment, using recently established populations of the bull-headed shrike Lanius bucephalus, which naturally colonized three subtropical islands in Japan. We compared flight initiation distance (FID), the distance at which an individual approached by a human initiates flight, between the islands and the temperate mainland. FID was longer for the insular shrikes compared with the mainland shrikes after controlling for other factors, indicating that the individuals which had invaded a new natural environment had a lower propensity for risk-taking. A possible explanation for these results is that low risk-taking behavior might be adaptive on the islands due to predation by the black rat Rattus rattus, an unfamiliar predator not found in shrike habitats on the temperate mainland. Further studies are needed to examine the nest predation rate, predator species, and nest site selection of these insular shrike populations.

Pre- to post-fledging carryover effects and the adaptive significance of variation in wing development for juvenile songbirds.

Evolutionary ecologists have long been interested in the adaptive significance of morphological traits across stages of animal life. In some cases, traits that are not adaptive in one life stage may be adaptive in a subsequent stage. As such, morphological traits may generate important carryover effects, whereby conditions experienced during one life-history stage influence fitness during subsequent stages. Carryover effects are particularly relevant in young animals, as early life stages are thought to be critical with respect to animal life-history evolution and population dynamics. In songbirds, pre- to post-fledging carryover effects operating within species may be critical for survival and shape life histories among species, but remain poorly understood. Among potential songbird traits, wing development and its associated flight ability may be the most important for post-fledging survival. Thus, to assess the adaptive significance of wing development for juvenile songbirds under Arnold's (Integrative and Comparative Biology, 23, 1983, 347) classic performance-morphology-fitness paradigm, we tested for pre- to post-fledging carryover effects among 20 coexisting species (nine focal species) of an avian community in east-central Illinois, USA. We found evidence for pre- to post-fledging carryover effects of wing development in all species, by which individuals with less developed wings exhibited poorer flight ability and experienced higher rates of mortality after fledging. Furthermore, our findings suggest that carryover effects operating at the species level ultimately help shape patterns of life-history variation among species. Specifically, we found that species with higher rates of nest predation had shorter nestling periods, fledged young with less developed wings and exhibited higher rates of post-fledging mortality. Our results highlight the adaptive significance of wing development as a key factor generating pre- to post-fledging carryover effects among songbirds, and demonstrate how morphological traits, locomotor performance, and age-specific survival may trade-off and interact across juvenile life stages to shape animal life histories.

Downside in habitat restoration: Predation of artificial nests by invasive rodents in Macaronesian laurel forest

This study assessed black rat predation on artificial nests in relation to restoration undertaken in the Macaronesian laurel forest in São Miguel Island, Azores, evaluating three different points: nest predation rate; rodent relative abundance; and abundance of invertebrates, flowers and fruits. In general, artificial nest predation increased after habitat restoration, and significant differences were found on a successfully restored forest site between year 0 and year 10. Rodent capture rates were significantly higher one decade after habitat restoration, and there were significantly more flowers and fruits available in the area with a higher restoration success than in the area with less restoration success. The results show that habitat restoration leads to an increase of black rat relative abundance, which is consistent with the increasing of artificial nest predation, and with the higher abundance of vegetal food on the successfully restored forest site. It is important to study and analyze these complex interactions which can have an influence on the survival of target species to conserve.

High tourism activity alters the spatial distribution of Hazel Grouse (Tetrastes bonasia) and predation on artificial nests in a high-mountain habitat

Human presence can significantly reduce habitat availability for wildlife. We investigated the impact of the distance from hiking trails and number of tourists on the number of sites occupied by Hazel Grouse (Tetrastes bonasia) and on the predation rate of artificial nests in two forest types (spruce and beech) in the Tatra Mountains (Poland). The study was carried out in the Tatra National Park from 2009 to 2014. Presence of Hazel Grouse males was detected in spring by playing territorial calls of this species from an electronic device. A total of 79 sites occupied by Hazel Grouse were found, and 174 artificial ground nests were monitored. Data on the number of tourists gathered at entry points and at trail crossings in the Tatra National Park were used to estimate levels of tourism activity. Sites occupied by Hazel Grouse were mostly located farther from hiking trails and in places with low tourist numbers. Artificial nests were mainly predated by mammals (85%) in both spruce and beech forests.

Solitary breeding barn swallows pay a higher nest defense cost

Successful reproduction depends on the ability of parents to defend from nest predators. Breeding birds often put their life at risk to defend their offspring from predators. Communal nest defense has been proposed as an individual benefit of group living. We tested this by experimentally exposing a short-lived avian species to a potential risk of predation. We presented decoys of both a diurnal and a nocturnal predator to barn swallows Hirundo rustica breeding solitarily and in large colonies in South-western Spain. We found clear benefits of group living compared to solitary pairs in relation to investment in individual nest defense and the capacity to deter a challenging predator. Although we did not find differences in the time needed to detect the predator, we found that the number of individuals recruited to participate in nest defense was greater for colonial breeding pairs, leading to fewer attacks per individual in comparison to solitary breeding pairs. We also found that barn swallows defended their nests more vigorously against a nocturnal predator than against a diurnal predator. Therefore, barn swallows living in groups obtained clear benefits in communal nest defense by reducing the risk, energy and time dedicated to nest defense. Colonial breeding is thus a more effective strategy for decreasing nest predation rates.

Vegetation structure influences predation rates of early nests in subarctic breeding waders

Ground‐nesting species are vulnerable to a wide range of predators and often experience very high levels of nest predation. Strategies to reduce nest vulnerability can include concealing nests in vegetation and/or nesting in locations in which nests and eggs are camouflaged and less easy for predators to locate. These strategies could have important implications for the distribution of ground‐nesting species and the success rates of nests in areas with differing vegetation structure. However, the factors influencing the success of nest concealment and camouflage strategies in ground‐nesting species are complex. Here we explore the effects of local vegetation structure and extent of nest concealment on nest predation rates in a range of ground‐nesting, sympatric wader species with differing nest concealment strategies (open‐nest species: Oystercatcher Haematopus ostralegus, Golden Plover Pluvialis apricaria and Whimbrel Numenius phaeopus; concealed‐nest species: Black‐tailed Godwit Limosa limosa, Redshank Tringa totanus and Snipe Gallinago gallinago) in south Iceland, in landscapes that comprise substantial variability in vegetation structure at a range of scales. We monitored 469 nests of these six wader species in 2015 and 2016 and ~40% of these nests were predated. Nest predation rates were similar for open‐nest and concealed‐nest species and did not vary with vegetation structure in the surrounding landscape, but nest‐concealing species were ~10% more likely to have nests predated when they were poorly concealed, and the frequency of poorly concealed nests was higher in colder conditions at the start of the breeding season. For concealed‐nest species, the reduced capacity to hide nests in colder conditions is likely to reflect low rates of vegetation growth in such conditions. The ongoing trend for warmer springs at subarctic latitudes could result in more rapid vegetation growth, with consequent increases in the success rates of early nests of concealed‐nest species. Temperature‐related effects on nest concealment from predators could thus be an important mechanism through which climate change affecting vegetation could have population‐level impacts on breeding birds at higher latitudes.

Do habitat preferences improve fitness? Context-specific adaptive habitat selection by a grassland songbird.

Animals are predicted to prefer high-quality over low-quality habitats, but adaptive habitat selection is less straightforward than often assumed. Preferences may improve only specific fitness metrics at particular spatial scales, with variation across time or between sexes. Preferences sometimes even reduce fitness. We investigated the context specificity of adaptive habitat selection, studying dickcissels (Spiza americana)-a polygynous songbird-as a model. From 2014 to 2015, we measured male and female habitat preferences at two scales (territories and landscape patches) on 21 grassland patches in Ringgold County, Iowa, USA. We tested whether preferences improved four fitness metrics-polygyny, avoidance of brood parasitism by brown-headed cowbirds (Molothrus ater), fledgling productivity, and offspring condition. Both sexes preferred territories where offspring attained superior condition and patches where parasitism was infrequent. Females preferred patches where nests produced more fledglings, and in 2014, males on preferred (i.e., early-established) territories attracted more mates and produced more fledglings. However, males on non-preferred (i.e., late-established) territories were more successful in 2015. This inconsistency may have arisen because females were abundant and nest-predation rates were low in May-June 2014, allowing early-settling males to produce many young. In 2015, however, females were more abundant and nests more successful later in the breeding season. Our results show that habitat preferences do not uniformly improve fitness, and some benefits differ between sexes. Moreover, preference-fitness relationships only manifest at specific scales, and annual variation in population and predation dynamics can limit consistency. Detecting adaptive habitat selection thus requires multi-year measurements and careful consideration of relevant scales.

The roles of temperature, nest predators and information parasites for geographical variation in egg covering behaviour of tits (Paridae)

AbstractAimNest building is widespread among animals. Nests may provide receptacles for eggs, developing offspring and the parents, and protect them from adverse environmental conditions. Nests may also indicate the quality of the territory and its owner and can be considered as an extended phenotype of its builder(s). Nests may, thus, function as a sexual and social signal. Here, we examined ecological and abiotic factors—temperature, nest predation and interspecific information utilization—shaping geographical variation in a specific nest structure—hair and feather cover of eggs—and its function as an extended phenotype before incubation in great (Parus major) and blue tits (Cyanistes caeruleus) across Europe. We also tested whether egg covering is associated with reproductive success of great tits.LocationFourteen different study sites and 28 populations across Europe.TaxonParus major, Cyanistes caeruleus.MethodsWe recorded clutch coverage estimates and collected egg covering nest material from the tit nests. We also measured nest specific breeding parameters and phenotypic measurements on adults. We tested whether mean spring temperatures, nest predation rates and flycatcher (Ficedula spp) densities in the study areas explain the large‐scale geographical variation of clutch coverage and reproductive success of tits.ResultsThe degree of egg coverage of great tits increased with lower mean spring temperature, higher nest predation rate and higher flycatcher density. We did not find egg covering of blue tits to be associated with any of the ecological or abiotic factors. Moreover, egg covering of great tits was not associated with reproductive success in our cross‐sectional data, yet a rigorous assessment of fitness effects would require long‐term data.Main conclusionsOur findings suggest that, in great tits, egg covering may simultaneously provide thermal insulation against cold temperatures during egg‐laying in spring and also represent a counter‐adaptation to reduce information parasitism by flycatchers and nest predation. Hence, geographical variation in interspecific interactions, and consequently in co‐evolutionary processes, may affect the evolution of nest characteristics besides environmental conditions.

Nest predation and adult mortality relationships with post-natal metabolic rates and growth among songbird species.

Metabolism is thought to mediate the connection between environmental selection pressures and a broad array of life history tradeoffs, but tests are needed. High juvenile predation correlates with fast growth, which may be achieved via fast juvenile metabolism. Fast offspring metabolism and growth can create physiological costs later in life that should be minimized in species with low adult mortality. Yet, relationships between juvenile metabolism and mortality at offspring versus adult stages are unexplored. We found that post-natal metabolism was positively correlated with adult mortality but not nest predation rates among 43 songbird species on three continents. Nest predation, but not adult mortality, explained additional variation in growth rates beyond metabolism. Our results suggest that metabolism may not be the mechanism underlying the relationships between growth and mortality at different life stages.

Alien predation in wetlands – the Raccoon Dog and water birds breeding success

Alien predators are known to potentially strongly affect their prey populations. We studied the impact of raccoon dogs (Nyctereutes procyonoides) on waterbird breeding success in eight semi-urban wetlands in Finland. We manipulated raccoon dog density in two wetlands by removing individuals (2002 protection year, 2003 and 2004 removal years). We additionally performed nest predation experiments. We monitored raccoon dog density, estimated hunting bag size and observed waterbird breeding success. Our hypothesis predicts that the omnivorous raccoon dog plays a role in waterbird breeding success by depredating nests. Our experiments shown that the raccoon dog hunting bag in eutrophic wetlands may be large, as we removed 8.6–20.0 animals per km2. Both our nest predation experiment and field data indicated that raccoon dogs affect the breeding success of waterbirds. We found a significant relationship between raccoon dog density index and predation rate of the artificial nests, but not between red fox (Vulpes vulpes) density and predation on artificial nests. We did not find an association between raccoon dog abundance and the breeding success of mallards (Anas platyrhynchos) and great crested grebes (Podiceps cristatus). However, our study shows that birds species with different breeding strategies – e.g. great crested grebe, mute swan (Cygnus olor), mallard, Eurasian wigeon (Mareca penelope), coot (Fulica atra), lapwing (Vanellus vanellus) and marsh harrier (Circus aeruginosus) – when considered together showed higher breeding success both in 2003 and 2004 when compared to breeding success before removal. There was, however, variation in how strongly the species responded to raccoon dog removal. Our results indicate that the removal of alien raccoon dogs can be an important tool in wetland management.
 Keywords: ducks, invasive species, lapwing, nest predation experiment, Nyctereutes procyonoides, predator removal