Aggressive Nest Defense Research Articles

Seasonal increase in intensity of nest defence against little cuckoos by Japanese bush warblers

Avian brood parasitism reduces the reproductive success of hosts. Thus, hosts have evolved antiparasite strategies such as rejection of parasitic eggs and aggressive nest defence against brood parasites. Japanese bush warblers, Cettia diphone , do not reject the parasitic eggs of little cuckoos, Cuculus poliocephalus , because their eggs mimic warblers’ eggs. To examine whether Japanese bush warblers show nest defence behaviour against their parasite, I investigated the responses of the warblers to a little cuckoo dummy. Japanese bush warblers are residents, while little cuckoos are summer visitors; thus, the warblers start breeding earlier than the cuckoos. Accordingly, the risk of being parasitized increases as the season progresses. Therefore, I also examined whether the intensity of nest defence differed before and after cuckoo arrival. Japanese bush warblers showed remarkably aggressive responses to the cuckoo dummy, and levels of aggression were higher after the cuckoo arrived. These results suggest that Japanese bush warblers adaptively adjust their nest defence behaviour in response to increased risk of being parasitized. This study indicates that differences in migratory habits between hosts and brood parasites produce seasonal changes in antiparasite behaviour.

Circulating androgens are influenced by parental nest defense in a wild teleost fish

While social interactions influence vertebrate endocrine regulation, the dynamics of regulation in relation to specific behaviors have not been clearly elucidated. In the current study, we investigated whether androgens (testosterone) or glucocorticoids (cortisol) play a functional role in aggressive offspring defense behavior in wild smallmouth bass (Micropterus dolomieu), a teleost fish with sole paternal care. We measured circulating testosterone and cortisol concentrations in plasma samples taken from parental males following a simulated nest intrusion by a common nest predator, the bluegill sunfish (Lepomis macrochirus). To understand whether endocrine regulation changes across the parental care period, we looked both at males guarding fresh eggs and at males guarding hatched embryos. Plasma testosterone levels increased in males subjected to a simulated nest intrusion when compared to sham controls. Testosterone concentrations in males guarding embryos were lower than in males guarding fresh eggs, but circulating testosterone was positively correlated with the level of aggression towards the nest predator at both offspring development stages. However, there was no increase in cortisol levels following a simulated nest intrusion, and no relationship between cortisol and any measured parameter. These results suggest that androgens play an important role in promoting aggressive nest defense behavior in teleost fish.

Aggressive Ural owl mothers recruit more offspring

Animals are thought to adjust their behavior optimally to any given environment. So-called behavioral syndromes, or consistent patterns of behavior across environments, contradict this assumption of unlimited plasticity. We studied nest defense aggressiveness of female Ural owls (244 females with 482 breeding attempts) breeding in a highly variable environment created by fluctuations in the abundance of their main prey (field and bank voles) across years. Ural owls were more aggressive when voles were increasing in density as well as when the Ural owls had large brood sizes and laid early in the season. Aggressive nest defense was highly repeatable between breeding attempts (r ¼ 0.52 6 0.05 standard error), but individuals also differed in their plasticity (the extent to which they adjusted the level of their aggression to the varying food conditions). Fierce nest defenders produced more recruits to the local breeding population, but a female’s survival was not affected by her intensity of nest defense. A path analysis revealed that nest defense aggressiveness, rather than its correlates vole abundance, brood size, or laying date, best explained offspring recruitment. Our findings provide an ultimate explanation for the Ural owl’s extremely aggressive nest defense. Key words: natural selection, nest defense, personality, Strix uralensis, survival, temperament, vole cycle. [Behav Ecol]

ANNUAL VARIATION IN THE BENEFITS OF A NESTING ASSOCIATION BETWEEN RED PHALAROPES (PHALAROPUS FULICARIUS) AND SABINE'S GULLS (XEMA SABINI)

Abstract By nesting near aggressive birds, timid species can reap the benefits of aggressive nest defense while avoiding the costs. Red Phalaropes (Phalaropus fulicarius; hereafter “phalaropes”) typically nest in grass-sedge marshes, but nests have also been noted in rocky coastal habitats. We studied the reproductive ecology of phalaropes at East Bay, Southampton Island, Nunavut, to determine whether their use of coastal nest areas reflected a protective nesting association with an aggressive larid, the Sabine's Gull (Xema sabini; hereafter “gull”). From 2000 to 2002, we found and monitored 29 phalarope nests with gull nests nearby (≤150 m away) and 26 without gulls nearby. Coastal phalarope nests were nearer to gull nests than expected by chance. No habitat differences were detected between coastal areas with and without gull nests, but only three phalarope nests were found in coastal areas without gull nests. Thermistor probes inserted in phalarope nests revealed that incubators with gulls nearby behav...

Annual Variation in the Benefits of a Nesting Association Between Red Phalaropes (Phalaropus Fulicarius) and Sabine's Gulls (Xema Sabini)

AbstractBy nesting near aggressive birds, timid species can reap the benefits of aggressive nest defense while avoiding the costs. Red Phalaropes (Phalaropus fulicarius; hereafter “phalaropes”) typically nest in grass-sedge marshes, but nests have also been noted in rocky coastal habitats. We studied the reproductive ecology of phalaropes at East Bay, Southampton Island, Nunavut, to determine whether their use of coastal nest areas reflected a protective nesting association with an aggressive larid, the Sabine's Gull (Xema sabini; hereafter “gull”). From 2000 to 2002, we found and monitored 29 phalarope nests with gull nests nearby (≤150 m away) and 26 without gulls nearby. Coastal phalarope nests were nearer to gull nests than expected by chance. No habitat differences were detected between coastal areas with and without gull nests, but only three phalarope nests were found in coastal areas without gull nests. Thermistor probes inserted in phalarope nests revealed that incubators with gulls nearby behaved less cryptically, taking more frequent and longer incubation recesses. In human-approach experiments, phalaropes with gulls nearby flushed earlier than those without gulls. In 2000 and 2001, hatch success was 17–20% higher for phalaropes with gulls nearby, but these nests had lower success rates than those without nearby gulls in 2002. These gulls are able to defend their nests from avian predators only; in 2002, arctic foxes (Alopex lagopus) were abundant, and their primary prey, collared lemmings (Dicrostonyx torquatus), were scarce. We suggest that phalaropes select coastal areas near gulls, but that this association is beneficial to phalaropes only in years when egg predation by arctic foxes is low.Variation Annuelle des Bénéfices d'une Association pour Nicher entre Phalaropus fulicarius et Xema sabini

POTENTIAL FACTORS INFLUENCING NEST DEFENSE IN DIURNAL NORTH AMERICAN RAPTORS

Nesting habitat, predator type, and level of reproductive effort influence nest defense behaviors in many bird species, yet no study has examined these or other possible factors influencing nest defense in a cross-species comparison for raptors. Using data from the literature, we grouped the nest defense behaviors of 19 diurnal North American raptors into four categories based on a gradient of aggressiveness. For each species, we identified the cover types where nesting occurred, accessibility of nest location, assessed two indices of reproductive effort, and examined associations between these factors and nest-defense behavior. We also we examined responses by raptor species to different predator types including diurnal avian, nocturnal avian, mammalian (not human), and human. Most raptor species with high reproductive effort exhibited very aggressive nest defense. Most raptor species nesting in open cover types and species with accessible nests showed aggressive nest defense. While many raptors react aggressively toward diurnal and nocturnal avian predators, they exhibit less aggressive defense against potential human predators. Results from this study suggest that a variety of factors may influence nest-defense strategies used by diurnal raptors. However, more work is needed on the relative influence of these factors (including predation risk) and variation in raptor nest defense strategies before general patterns can be elucidated.

Nest-Site Characteristics and Nesting Success of the Greater Pewee in Arizona

Nest-Site Characteristics and Nesting Success of the Greater Pewee in Arizona

Comparative Analysis of Habitat Selection, Nest Site and Nest Success by Cedar Waxwings (Bombycilla cedrorum) and Eastern Kingbirds (Tyrannus tyrannus)

-We compared nest success, habitat use and nest site selection of cedar waxwings (Bombycilla cedrorum) and eastern kingbirds (Tyrannus tyrannus) breeding in the same locations over a 3-yr period to determine if nest success differed between species, or with habitat or nest sites. Nest success was lower in waxwings in all 3 yr (3-yr average: 18% vs. 55%). Both species preferred hawthorns (Crataegus) as nest trees, but in neither species was nest success higher when nests were placed in hawthorns. Nest success did, however, vary with habitat structure: successful kingbirds nests were usually located in the most open habitat (i.e., lowest canopy cover and surrounded by the fewest trees), whereas failed waxwing nests were located in habitats with the densest vegetation. Habitats of failed kingbird and successful waxwing nests were intermediate and similar. Nest sites were very similar, except that waxwing nests were much more concealed in the nest tree's vegetation. However, neither cover nor other nest site variables differed between failed and successful nests within either species. A discriminant function analysis that used mainly habitat variables correctly classified 68% of failed waxwing and 64% of successful kingbird nests, but less than 50% of failed kingbird and successful waxwing nests. Thus, kingbirds and waxwings overlap extensively in habitat use and nest sites, but kingbirds prefer more open habitats, presumably because it allows them to detect predators and defend their nests. Waxwings prefer habitats with denser vegetation, presumably because they rely upon inconspicuous behavior to avoid nest predators. Failed kingbird nests were in waxwing-like habitats, suggesting a link between nest sites, habitats and parental behavior. We believe that the characteristic aggressive nest defense of kingbirds was the major reason for their higher nesting success.

Factors related to aggressive nest protection behaviour: a comparative study of Holarctic waders

Data on 12 factors presumed to influence the distribution of aggressive nest defence in 111 species of waders (incubation-sharing by the parents, number of parents present near the nest, incubation time, nest habitat, breeding latitude, body mass, wing loading, wing structure, detectability on the nest, predator regime, coloniality and alternative prey) were collected from literature and field researchers. Body mass and number of parents present on the nest territory (within response range when avian predators appear) explain 50% of the variation in aggressive defence behaviour. The results support the notion that ecological conditions like predation pressure are important in shaping wader parental care systems, with implications for mating systems. Altogether, the investigated factors explain around 70% of the variation in the samples. Future research on the level of individuals is suggested in order to explain the remaining variation.

Experiments on the Responses of a Rejector Species to Threats of Predation and Cowbird Parasitism

AbstractWe presented freeze‐dried models of a nondescript sparrow (control), a female brown‐headed cowbird (Molothrus ater, Icterinae) and an avian nest predator to nesting eastern kingbirds (Tyrannus tyrannus, Tyranninae) during the egg‐laying and nestling stages to test for nest defense against the threat of cowbird parasitism. Both kingbird parents responded during 81% of the 183 trials. Kingbirds responded aggressively toward the cowbird model, but only slightly more so than to the control, and less than to the predator model. The level of aggression directed toward the predator increased between the laying and nestling stages. The results suggest that kingbirds at Delta Marsh, Manitoba, did not recognize the cowbird as a unique or dangerous threat, possibly because of low selection pressure on this rejector species for aggressive nest defense against cowbirds.

Anti-predator behaviour and mating systems in waders: aggressive nest defence selects for monogamy

Data collected from the literature on anti-predator behaviour, body weight and mating systems of 90 Holarctic waders are presented. Aggressive nest defence is correlated with body weight, heavy species being more likely to attack predators than are small species. Monogamy is common among large waders. Polygamy is generally restricted to small waders, and monogamous species are significantly more aggressive than polygamous species. Presumably, a certain body size is necessary to chase away predators, and being above this threshold size, two cooperating parents guard their nest and brood more efficiently than one parent. Small birds generally do not gain the same anti-predator advantage from monogamy as large birds, and this is presumed to explain the high frequency of polygamous mating systems in small waders.

African bees in the Americas: Insights from biogeography and genetics

The spread of African honey bees in South and Central America is one of the most remarkable and certainly among the most highly publicized instances of biological invasion. Their aggressive nest defense has led to numerous stinging incidents and even deaths; aggressiveness, coupled with a tendency to abandon the nest when disturbed, has also caused serious disruption of beekeeping and pollination industries in regions that they have invaded. The rapid spread of African bees in the Americas and their recent arrival in the United States have sparked interest in development of genetic tools for identification of honeybee populations. This in turn has renewed interest in honeybee biogeography.

Nest Success and Nesting Habits of Eastern Kingbirds and Other Flycatchers

Patterns of nest placement and its relationship to nest success in the Eastern Kingbird (Tyrannus tyrannus) were studied in populations breeding in New York and Kansas. Data were augmented with information on nest placement in other open-nesting tyrannids in order to examine the hypothesis that these flycatchers place their nests chiefly so as to conceal them from predators. Nesting success was significantly greater in New York than in Kansas but was relatively high in both populations, as is apparently true of North American breeding flycatchers in general. Geographic variation in nest placement in the Eastern Kingbird was relatively small and statistical comparisons of failed and successful nests indicated that nests placed at mid-heights in the tree, and about midway between the center of the tree and canopy edge, were most successful. These nest sites were also the most commonly used sites. Increased vegetative cover around the nest and a greater number of supporting branches for the nest were also associated with success, and it is their interaction with nest height and distance from the canopy edge that is apparently most important in determining success. Most tyrant flycatchers nest several meters or more above the ground, and interspecific variation in nest placement matches the range of sites used by Eastern Kingbirds. Aggressive nest defense is apparently characteristic of the family, and average nest height is also positively correlated with length of the nestling period. These facts support the predator-avoidance hypothesis and suggest that nest placement habits and aggressive nest defense are means by which open-nesting birds can reduce rates of nestling mortality.