Subsequent Nest Research Articles

Avian Habitat Selection: Pattern from Process in Nest-Site Use by Ducks?

Patterns of habitat use in animals presumably have evolved in response to diverse selective processes, so we first examined whether the theory of natural selection formed the conceptual framework for published studies (N = 270) of nest-site selection by birds. Most (61%) studies of nest-site selection tested for pattern arising from natural selection (whether used nest habitat differed from available nesting habitat), many (54%) tested for evidence of the process of natural selection (whether unsuccessful nests differed from successful nests), some (10%) tested whether the process of natural selection caused subsequent adaptation, but remarkably few conceptually linked these elements or used the theory of natural selection as the rationale for their questions. We then tested for evidence of natural (phenotypic) selection with data for six species of ducks. At nests, we used six variables to describe vegetation structure/nest position and categorized patch types (pond edge, native grass, planted cover, shrubs, or trees) in which nests were found; nest fates (abandoned, depredated, or successful) were also determined. For Blue-winged Teal (Anas discors), Northern Shoveler (A. clypeata), and Mallard (A. platyrhynchos), there were significant patterns of nonrandom nest-site placement within a gradient of vegetation structure/nest position. For Blue-winged Teal and Gadwall (A. strepera), nest success varied within these gradients in a way that could exert directional selection. Several tests for adaptive nest-site choice were conducted. Nest fate did not influence fidelity of females to patch types. However, Mallards with previously unsuccessful nests dispersed farther than females with previously successful nests. Nonetheless, neither fidelity to patch type nor dispersal distance influenced subsequent nest success. In the long term (over 8 yr), there was a weak tendency within species for nest density to be higher among patch types where relative nest success was higher. In the short term (from year t to year t + 1), this pattern was not observed in a vegetation-structure/nest-position gradient for any species. The strongest evidence of adaptive response to nest fate was higher nest density on an island where nest success was relatively high.

Habitat Use of Eastern Wild Turkeys in Central Mississippi

Most past studies of wild turkey (Meleagris gallopavo) habitat use were limited to 1 spatial scale. were of short duration, and had not simultaneously examined habitat use by both sexes. We used compositional analysis to describe habitat use of an castern wild turkey (M. g silvestris) population in central Mississippi at 3 spatial scales (study area, home range, within home range). We conducted the study on the 14,410-ha Tallahala Wildlife Management Area (TWMA), which was composed of hardwood, pine, and pine-hardwood stands of various ages. Overall, turkevs of both sexes preferred pine and hardwood sawtimber most, and poletimber stands least Throughout the vear, females primarily used hardwood sawtimber stands, but males tended to use pine sawtimber. Habital use by females during preincubation may have influenced subsequent nest success. Habitat use at 3 spatial scales was similar and was reflective of the adaptable nature of wild turkeys and the high degree of habitat heterogencity on the study area.

AVIAN HABITAT SELECTION: PATTERN FROM PROCESS IN NEST-SITE USE BY DUCKS?

Patterns of habitat use in animals presumably have evolved in response to diverse selective processes, so we first examined whether the theory of natural selection formed the conceptual framework for published studies (N = 270) of nest-site selection by birds. Most (61%) studies of nest-site selection tested for pattern arising from natural selection (whether used nest habitat differed from available nesting habitat), many (54%) tested for evidence of the process of natural selection (whether unsuccessful nests differed from successful nests), some (10%) tested whether the process of natural selection caused subsequent adaptation, but remarkably few conceptually linked these elements or used the theory of natural selection as the rationale for their questions. We then tested for evidence of natural (phenotypic) selection with data for six species of ducks. At nests, we used six variables to describe vegetation structure/nest position and categorized patch types (pond edge, native grass, planted cover, shrubs, or trees) in which nests were found; nest fates (abandoned, depredated, or successful) were also determined. For Blue-winged Teal (Anas discors), Northern Shoveler (A. clypeata), and Mallard (A. platyrhynchos), there were significant patterns of nonrandom nest-site placement within a gradient of vegetation structure/nest position. For Blue-winged Teal and Gadwall (A. strepera), nest success varied within these gradients in a way that could exert directional selection. Several tests for adaptive nest-site choice were conducted. Nest fate did not influence fidelity of females to patch types. However, Mallards with previously unsuccessful nests dispersed farther than females with previously successful nests. Nonetheless, neither fidelity to patch type nor dispersal distance influenced subsequent nest success. In the long term (over 8 yr), there was a weak tendency within species for nest density to be higher among patch types where relative nest success was higher. In the short term (from year t to year t + 1), this pattern was not observed in a vegetation-structure/nest-position gradient for any species. The strongest evidence of adaptive response to nest fate was higher nest density on an island where nest success was relatively high.

Effect of Incubation Body Mass on Reproductive Success and Survival of Two European Diving Ducks: A Test of the Nutrient Limitation Hypothesis

The nutrient limitation hypothesis postulates that variation in nutrient reserves during egg laying and incubation are important predictors of future reproductive success of female waterfowl. We tested one component of this hypothesis in two European diving ducks, Common Pochard (Aythya ferina) and Tufted Duck (Aythya fuligula), relating body masses of incubating females to subsequent nest success, and to duckling and adult survival. We based our analyses on 3,224 Common Pochards and 1,812 Tufted Ducks captured and weighed during the last two weeks before ducklings hatched at Engure Marsh, Latvia, in 1978-1993. Adult (ASY) females from successful nests weighed significantly more than those from abandoned nests, but differences in body masses between two categories of nest fates were negligible for yearlings (SY). For both species, survival (measured as apparent return rate) of females (SY + ASY) was unrelated to their body masses. Duckling recruitment was independent of adult female body mass for both species, but yearling Common Pochards that provided recruits weighed more than those that produced none. Results of our study support the nutrient limitation hypothesis and we conclude that nutrient reserve levels may be important determinants of nest success in female ducks in general, especially for species that rely heavily on endogenous reserves during incubation.

Habitat Sampling and Habitat Selection by Female Wild Turkeys: Ecological Correlates and Reproductive Consequences

ABST,Acr.--Habitat sampling can allow much more effective habitat selection for longterm activities such as nesting and may be directly linked to fitness. We studied the process of habitat sampling and selection in female Wild Turkeys (Meleagris gallopavo) in the Arkansas Ozarks. In particular, we tested the prediction that movements prior to selecting nesting habitat correlate with the quality of selected habitat. Our results supported the prediction that greater habitat sampling (as reflected by greater area covered prior to nesting) allows acquisition of better nesting habitat; greater movements were correlated with choice of better nesting sites with more cover that allow higher nest survival. Attributes of individual birds and habitat dispersion influenced movement patterns and access to quality habitats. In addition, extent of habitat sampling early in the season correlated with reproductive performance by affecting renesting. Distance between subsequent nest locations was inversely related to the movements early in the season and also depended upon length of incubation before nest predation. Females that sampled larger areas after depredation of their first nest and did so outside of their prenesting range were more successful than other females. Received 11 August 1995, accepted 10 November 1995. HABITAT USE can influence reproduction and survival and, thus, affect the evolution of many aspects of a species' biology (Whitham 1980, Cody 1985, Martin 1993). In particular, variation in habitat quality should favor individuals that choose habitats that yield the greatest reproductive success and survival (Fretwell and Lucas 1970, Fretwell 1972, Whitham 1980, Mar

Succession, Forest Fragmentation, and the Distribution of Wood Ants

I tested the hypothesis that the distribution of territorial wood-ant species (Formica rufa group) of different colony structure and dispersal strategy relate differently to the dynamics and landscape structure of boreal forests. Monogynous species (colonies have only one queen and inhabit one nest) that disperse through nuptial flight and subsequent temporary nest parasitism, should primarily be found in young forests and in smaller old-forest fragments. These long-distance dispersers can reach these areas where the nests of F. fusca group ants (which the wood-ant queens invade and parasitize) are more common, and these wood-ant colonies can monopolize the small fragments. Polygynous species (colonies have many queens) that disperse mainly through nest budding and may form large colonies of cooperative nests, should primarily be found in old forests and larger old-forest fragments. In such patches these short-distance dispersers have enough space for developing into strong colonies capable of ruling out all other territorial species. I mapped the nests of eight territorial ant species, three of which belonged to the wood-ant group, in fragmented forests of different age in southern Finland. In general, the mapping data supported my hypotheses. The monogynous F. lugubris was more common in young forests and in small old-forest fragments than expected by chance. The polygynous F. aquilonia was more common in old forests and in larger old-forest fragments.

Requirements for belief models in cooperative dialogue

Models of rationality typically rely on underlying logics that allow simulated agents to entertain beliefs about one another to any depth of nesting. Such models seem to be overly complex when used for belief modelling in environments in which cooperation between agents can be assumed, i.e., most HCI contexts. We examine some existing dialogue systems and find that deeply-nested beliefs are seldom supported, and that where present they appear to be unnecessary except in some situations involving deception. Use of nested beliefs is associated with nested reasoning (i.e., reasoning about other agents' reasoning). We argue that for cooperative dialogues, representations of individual nested beliefs of the third level (i.e., what A thinks B thinks A thinks B thinks) and beyond are in principle unnecessary unless directly available from the environment, because the corresponding nested reasoning is redundant. Since cooperation sometimes requires that agents reason about what is mutually believed, we propose a representation in which the second and all subsequent nesting levels are merged into a single category. In situations affording individual deeply-nested beliefs, such a representation restricts agents to human-like referring and repair strategies, where an unrestricted agent might make an unrealistic and perplexing utterance.

Use of Artificial Brown-Headed Cowbird Eggs as a Potential Management Tool in Deterring Parasitism

We added artificial and real brown-headed cowbird (Molothrus ater) eggs to red-winged blackbird (Agelaius phoeniceus) nests in 1985 and 1991 to determine the effect of egg addition on subsequent nest parasitism. We added large artificial eggs measuring 26.1 × 17.2 mm, similar in size to red-winged blackbird eggs, and small artificial eggs measuring 20.1 × 16.1 mm, similar in size to brown-headed cowbird eggs. Brown-headed cowbirds avoided parasitizing nests to which we added real or artificial cowbird eggs. In 1985, only 5.3% (3 of 57) of experimental nests were parasitized by cowbirds, compared with 31.5% parasitism of control nests (P = 0.001, n = 54)

The influence of egg survivorship on the subsequent nest fidelity of female bicolour damselfish, Stegastes partitus

Abstract. In many animal species, females lay eggs within male territories. Research on female choice in such species has shown that females often assess male or territory quality indirectly on the basis of male characters that are correlated with male or territory quality. Researchers have given much less attention to the possibility that females can assess male or territory quality directly based on the survival of previous broods. This study demonstrates that in the bicolour damselfish, a species with exclusive male parental care of eggs, females use the survival of previously-laid eggs to avoid nests that have a low probability of offspring survival. Females mate repeatedly during a reproductive cycle and although they generally show high nest fidelity, this fidelity is broken when a nest loses an entire brood to nocturnally feeding brittlestars. Experimental removal of broods and addition of brittlestar odours to nests demonstrate that brittlestar odours are sufficient to cause females to avoid nests. Females may also respond to visual cues associated with brood loss. In addition, clutches laid in nests after nocturnal complete-brood losses are much less likely to survive than clutches laid in nests that have not suffered nocturnal complete-brood losses. Therefore, by avoiding nests from which brittlestars have recently removed eggs, females increase the probability of future egg survival.

Parasitic Egg Laying In Canvasbacks: Frequency, Success, and Individual Behavior

ABsTRAcr.-Time-lapse photography and frequent nest checks conducted at Canvasback (Aythya valisineria) nests revealed a high frequency of intraspecific parasitic egg laying. At least 36% of completed Canvasback clutches were parasitized by other Canvasbacks, and at least 9.7% of all Canvasback eggs were laid parasitically during the three-year study. The maximum hatching success of nonparasitic Canvasback eggs in successful nests was 79%, while the maximum success of known parasitic eggs was only 29%. Individual patterns of parasitic and typical nesting behavior were variable. In 15 cases, however, a marked female laid one or a few parasitic eggs before initiating her own nest. These parasitic eggs and subsequent nest initiations followed the seasonal peak of Canvasback nest initiations, suggesting that these females may have abandoned or had destroyed an initial nest prior to laying parasitically. I suggest that some females lay parasitic eggs after an initial nesting attempt is terminated early in the laying stage and before a second nest is initiated because the time-consuming task of nest building prevents them from having a second nest immediately ready to receive eggs. Parasitic egg laying in Canvasbacks also may function as a lowcost alternative to typical nesting when environmental conditions are unfavorable. Several younger females were known only to lay parasitic eggs in 1988, when drought conditions reduced the probability of successful nesting. Parasitic egg laying is a regular feature of the biology of Canvasbacks, but is a relatively unsuccessful reproductive tactic employed only in best-of-a-bad-job situations. Received 17 April 1991, accepted 20 January 1992.

Antiphonal duetting and sex hormones in the tropical bush shrike Laniarius funebris (HARTLAUB)

We investigated changes in antiphonal duetting with phases of reproduction and circulating levels of luteinizing hormone, testosterone, and estradiol in slate-colored boubous ( Laniarius funebris) breeding in aviaries. Frequency of overall male singing did not vary with reproductive phase while frequencies of female singing and female vocal responses to male song were reduced during incubation and feeding of nestlings. This resulted in significant changes in frequency of duetting. Males sang the sexual song type M1 more often during courtship and nest building than during the nestlings phase. Their territorial song types M2 and M4 did not vary with breeding phase. Females were less responsive to M1 during incubation and to M2 during the nest building and nestlings than during the courtship phase. Plasma levels of luteinizing hormone and testosterone increased in males from the prebreeding to the courtship phase. While testosterone decreased already during nest building and remained low during subsequent phases of reproduction, luteinizing hormone decreased during incubation and feeding of nestlings. Female luteinizing hormone levels were highest during nest building. Female estradiol levels decreased from nest building to incubation and increased again during subsequent nest building. Female testosterone levels were low but not basal and did not vary with phase. Neither the overall male and female singing frequencies nor the frequencies of male song types were correlated with hormonal state. However, female participation in territorial duets M4 correlated positively with their testosterone levels. It is suggested that in this monogamous, duetting species with prolonged pairbonds behavioral cues between the mates are more important than the hormonal state in control of male and female singing.

Influence of Male and Female Quality on Clutch Size in Tits (Parus Spp.)

Field experiments were designed to examine the effects of parental ability on clutch size, for the two sexes separately. To handicap parental ability we removed feathers from the wings and the tail of three tit species (Parus spp.) during the initial incubation period. We then removed their first clutches, and examined the effect of the handicap on the subsequent nesting. In Blue Tits (P. caeruleus), and Coal Tits (P. ater), handicapped females reduced the size of the repeat clutch more than control females. In Blue Tits handicapped females fed their young at a lower rate, lost more body mass during the nestling period, and at fledging time their broods were significantly smaller than those of controls. Their fledglings had a body mass, similar to the control fledglings. Handicapped female Great Tits (P. major) only reduced their clutch size a small amount; consequently, at fledging time, their body mass and those of their young were lower than for controls. The males of the three species of tits did not seem to increase parental investment when their mate was handicapped. When male Blue and Coal Tits were handicapped their mates did not reduce clutch size more than did those of the control group, despite a reduction in parental investment by handicapped males. However, breeding success was not significantly affected by handicapping males. We conclude that the clutch size determination of female tits is primarily based on their own ability to feed their young, and not on the quality of their mate. Male tits seem to have a lesser influence on breeding success than females, and males seem less willing or less able to increase their parental investment.

Reproductive interactions of the Shiny Cowbird Molothrus bonariensis and the Yellow‐hooded Blackbird Agelaius icterocephalus in Trinidad

The reproductive interactions of the Shiny Cowbird Molothrus bonariensis, a brood parasite, and the Yellow‐hooded Blackbird Agelaius icterocephalus, a host of the cowbird, were studied In Trinidad, West Indies. We gathered information on the breeding biology of the Shiny Cowbird and the Yellow‐hooded Blackbird, the frequency of use of the host species, and the effects of brood parasitism on host breeding success. Yellow‐hooded Blackbirds are polygynous for the most part; males build nests and attempt to attract females to lay in them by means of song and visual displays directed towards the nests. This behaviour probably makes it easy for cowbirds to locate breeding birds and their nests. Cowbird eggs were found in 153 of 377 (40–3 %) blackbird nests located before the nestling stage. Shiny Cowbird parasitism of the Yellow‐hooded Blackbird had little negative impact on host reproductive success, whereas predation accounted for the majority of nest failures. Vigilant nest defense by male blackbirds combined with colonial breeding apparently also minimized the extent of host egg damage and removal by cowbirds, and the parasitized and unparasitized nests were equally successful at producing blackbirds. Cowbirds most frequently parasitized the first or only nesting attempts in blackbird territories, and first or only nests were also successful more frequently than subsequent nests.

Intraspecific nest parasitism in the European starling Sturnus vulgaris

Biochemical genetic markers were used along with conventional methods (abnormal laying sequence/clutch size, unusual egg shape/pigmentation) to identify intraspecific nest parasitism at two British nestbox colonies of the European starling. Between 11 and 37% of first clutches were parasitized during 1977–1979. Parasitic females probably comprised all of the following categories: (1) paired females contesting a nestbox occupied by another pair; (2) previously paired females who had laid a clutch but had been unsuccessful; (3) unpaired females who had copulated with males that already had a mate and nest site; and (4) ‘professional’ nest parasites who distributed at lest some of their eggs in one or more nests other than their own. Although parasitized nests had higher clutch sizes, parasitism led to fewer host young fledging per egg laid, mainly through the eviction of eggs and subsequent nest desertion. Number of parasitic young fledged per egg laid was highest when eggs were laid synchronously with the host, when host clutches were larger, or a smaller number of parasite eggs were added to a nest, thus favouring parasites that distribute their eggs amongst a number of nests. A greater pressure on nest sites may have accounted for the higher levels of parasitism at the Aberdeen colony and for the greater number of parasite eggs laid in a nest. Although most parasitic female starlings appeared to be much less successful than non-parasitic ones, nest parasitism in the starling might evolve directly when one or more of the following advantages are present. (1) There are no constraints on the number of eggs a female may lay but there are constraints on the number of young she may feed adequately. (2) Female survival is increased by having fewer or no eggs/young to care for. (3) Current feeding conditions favour the survival of more young than would be produced by the most common clutch size. Intraspecific nest parasitism is considered to be a first stage in the evolution of interspecific nest parasitism.

Do pinyon jays alter nest placement based on prior experience?

The role of prior experience in nest-site selection by a long-lived corvid, the pinyon jay, Gymnorhinus cyanocephalus, was investigated. The major sources of nest failure were loss to avian predators ( Corvus corax and Corvus brachyrhynchos) and abandonment after cold and snowy spring weather. Cold weather favours exposed nesting because solar radiation reduces the energetic costs to nesting females and quickly melts snow in and around the nest. Predation favours cryptic nests. The relative height at which individual jays nested (an index of nest exposure) was compared to their previous nest height and to the fate of that nesting attempt. For the following reasons jays appear to associate nest exposure with the fate of a particular nesting attempt: (1) after nesting in exposed sites, subsequent nests were 27·3% lower (more concealed) in the nest tree following predation, but only 9·7% lower when predation did not occur; (2) concealed nest sites were avoided only after failure due to cold weather; and (3) nest placement following the successful fledging of young did not differ significantly from the previous nest placement. The frequency of nesting in exposed locations dropped from 80% to 55% after individuals suffered their third predatory experience when nesting in exposed locations. Experienced jays nested relatively low throughout the season, which enhances concealment, but nested farther out from the trunk early in the season, which reduces incubation costs. The use of prior experience in nest-site selection is adaptive because sites can include properties associated with past success and exclude those associated with past failure.

Nest construction in the subsocial waspParischnogaster mellyi (Saussure) Stenogastrinae (Hymnoptera)

Nests ofParischnogaster mellyi were built upon long thin strands of hanging dead vegetation. The nest design varied from a single comb structure to cells spread along the length of the suspension. The preferred nest design was found to be an elongate nest with minimal cell was sharing. On a long nest suspension the first cell was placed remote from either end. Subsequent nest expansion extended both above and below this first cell. It is suggested that advantage of a long, narrow nest may be concealment from visual hunting predators. Nest material is composed of plant cuticle as well as woody stems. It has a composition of fine crumbs and flakes; in consequence it is fragile and unsuited to the large nests. It is suggested that the physical limitations of the nest material in stenogastrinae may have inhibited the evolution of large colony sizes.