Brood Parasitism Research Papers - Academia.edu (original) (raw)

2025, F1000 - Post-publication peer review of the biomedical literature

Parasitic infection has a direct physiological cost to hosts but may also alter how hosts interact with other individuals in their environment. Such indirect effects may alter both host fitness and the fitness of other individuals in the host's social network, yet the relative impact of direct and indirect effects of infection are rarely quantified. During reproduction, a host's social environment includes family members who may be in conflict over resource allocation. In such situations, infection may alter how resources are allocated, thereby redistributing the costs of parasitism between individuals. Here, we experimentally reduce parasite burdens of parent and/or nestling European shags (Phalacrocorax aristotelis) infected with Contracaecum nematodes in a factorial design, then simultaneously measure the impact of an individual's infection on all family members. We found no direct effect of infection on parent or offspring traits but indirect effects were detected in all group members, with both immediate effects (mass change and survival) and longer-term effects (timing of parents' subsequent breeding). Our results show that parasite infection can have a major impact on individuals other than the host, suggesting that the effect of parasites on population processes may be greater than previously thought.

2025

El Tordo Pirata (Molothrus oryzivora) como parásito de cría del Querrequerre (Cyanocorax yncas) en los Andes venezolanos.

2025, The Condor

We monitored 259 nests of six Brownheaded Cowbird (Molothrus ater) hosts within oldfield habitat on James Island, South Carolina during the 1997 and 1998 breeding seasons to determine the effect of parasitism on three nest-survival parameters (clutch size, hatching rate, and number of fledglings). We determined daily predation and parasitism rates, and probability of nest abandonment after parasitism to derive an estimate of seasonal fecundity. Clutch size of parasitized nests was reduced in four host species. Brood parasitism did not affect hatching rate in any species, and reduced the number of fledglings from only Blue Grosbeak (Guiraca caerulea) nests. Despite brood reduction during the nesting cycle, cowbird parasitism had little impact on seasonal fecundity of these host species because of low parasitism intensity, double-brooding behavior, and hosts' ability to raise their own young with cowbird young.

2025, The Wilson Bulletin

was studied in a New Jersey population of European Starlings (Sturnus vulgaris). Biopsy of both blood and pectoral muscle was done on 550 wild birds, including both adults and all chicks at 95 nests between 1983-1985. Vertical thin-layer polyacrylamide gel electrophoresis (PAGE) was employed rather than starch gel electrophoresis because we found through using both that PAGE has greater resolution for the enzymes we examined. Thirty-three loci were screened, but only three were both resolvable and found to have bona fide polymorphism. Two unambiguous cases of cuckoldry were discovered, each involving two chicks. Another six cases may have been either cuckoldry or intraspecific brood parasitism; they involved only one chick each. If only the two unambiguous cases are counted, the frequency of cuckoldry was 2.1%. If the six ambiguous cases are included, the frequency was 8.4%. Low measured frequencies do not necessarily imply a low risk of cuckoldry because they may reflect the conservatism of electrophoresis and the effectiveness of anticuckoldry behaviors. Cuckoldry may be a serious, but contained, risk in our population.

2025

Roadside point counts are generally used for large surveys to increase the number of samples. We examined differences in species detected from roadside versus off-road (200-m and 400-m) point counts in the Shenandoah National Park. We also compared the list of species detected in the first 3 minutes to those detected in 10 minutes for potential species biases. Results from 81 paired roadside and off-road counts indicated that roadside counts had higher numbers of several edge species but did not have lower numbers of nonedge forest species. More individuals and species were detected from roadside points because of this increase in edge species. Sixtyfive percent of the species detected in 10 minutes were recorded in the first 3 minutes.

2025

Brood parasitism: new events for the Shiny Cowbird Molothrus bonariensis Brood parasites lay their eggs in the nests of other species, thereby imposing on them the cost of parental care. In the Neotropics, the Shiny Cowbird Molothrus bonariensis is an obligate, generalist and opportunistic brood parasite with a wide and expanding range. This has led to an increase in the number of host species and potentially to fresh conservation problems. We searched for parasitic interactions in the Shiny Cowbird in Ecuador and documented 28 such events with 11 species. We added the Grey-browed Brush-finch Arremon assimilis and the Golden Grosbeak Pheucticus chrysogaster to the catalogue of previously known hosts (i.e., species that successfully raise the parasitic young). Additionally, we present here evidence of parasitism with the Eared Dove Zenaida auriculata, Fasciated Wren Campylorhynchus fasciatus, Thrush-like Wren C. turdinus and Tropical Mockingbird Mimus gilvus, which were previously listed only as victims (i.e., with no evidence of having successfully raised the parasitic young). We also increased the number of records of parasitism with the Peruvian Meadowlark Leistes bellicosus as a victim, and the Rufous-collared Sparrow Zonotrichia capensis, the Yellow-tailed Oriole Icterus mesomelas, the Scrub Blackbird Dives warczewiczi and the Silver-beaked Tanager Ramphocelus carbo as hosts. The Rufous-collared Sparrow seems to be the most commonly selected host in the Andean region of Ecuador. Although previously frequently recorded, many aspects of the natural history of this parasitic bird still need further research to preclude potential conservation problems in their host species.

2025

In present investigation nesting and breeding of common coot (Fulica atra) from Ujani-Bhigwan reservoir, Maharashtra, India. Total 56 nests were observed in study area, in which 31 eggs and 68 chicks were observed. Parameters such as depth of water, nest distance from river bank, shape of nest and nest material were assessed in this research. Nest construction, Parental care, and feeding to youngones are contributed by both of parents. The Typha angustifolia and Ipomoea carnea was main base for the nest construction of common coot (Fulica atra). Predator, over fishing, pollution, illegal sand mining, tourist activities and anthropogenic activity are threats identified to the nest of common coot (Fulica atra). It is an important primary data-base for this nesting site of Common coot with major details fist-time.

2025, Influence of Nesting Habitat and Nest Emplacement on the Breeding Success of the Black Francolin (Francolinus francolinus, Phasianidae): A Case Study from Pakistan

Limited research exists on the breeding ecology of the black francolin (Francolinus francolinus) in northern Pakistan. This study assessed egg dimensions, clutch size, hatching, fledging, and overall breeding success across different habitats and nests (n = 25) at Totali Game Reserve, Buner. Generalized linear models (GLMs) were used to analyze the effects of nest site characteristics and nest traits on breeding parameters. Egg dimensions were consistent across sites whereas bush nests had slightly wider eggs. The average clutch size was 5.9 ± 1.7 eggs, with an average of 4.8 ± 1.0 hatchlings per nest. A total of 111 chicks fledged, averaging 4.4 ± 1.0 per nest, yielding an overall breeding success rate of 75.5%. Nests containing six eggs had higher hatching success (76.6%). GLMs results showed a significant positive relationship between clutch size and hatchling, while nest site and traits had no significant effects. However, fledgling success was positively influenced by hatchling numbers, with nests in wetland habitats yielding significantly more fledglings (4.6 ± 0.9) than those from dryland habitats (4.0 ± 1.2). These findings suggest Black Francolins prefer nesting in wetland areas in bushes, likely due to better protection and favorable conditions.

2025

In social insects, newly emerged individuals learn the colony-specifi c chemical label from their natal comb shortly after their emergence. These labels help to identify each individual's colony of origin and are used as a recognition template against which individuals can discriminate nestmates from non-nestmates. Our previous studies with Polybia paulista von Ihering support this general pattern, and the acceptance rate of young female and male wasps decreased as a function of their age. Our study also showed in P. paulista that more than 90% of newly emerged female wasps might be accepted by conspecifi c unrelated colonies. However, it has not been investigated whether the acceptance rate of newly emerged female wasps depends on colony developmental stage of recipient colonies. We introduced newly emerged female wasps of P. paulista into different colony developmental stags of recipient colonies, i.e., worker-producing and male-producing colonies. We found that the acceptance rate of newly emerged female wasps by alien colonies was pretty lower by male-producing colonies than worker-producing colonies. This is the fi rst study to show that the acceptance rate of young female wasps depends on stages of recipient colonies.

2025, Ibis

We describe a population of Village Indigobirds Vidua chalybeata on the Zambezi River that parasitizes the nests and mimics the songs of a novel host species, Brown Firefinch Lagonosticta nitidula, yet coexists with a population that mimics the usual host species of this indigobird, Red‐billed Firefinch L. senegala. Male indigobirds mimicking the song of L. nitidula are morphologically indistinguishable from those that mimic songs of the usual host, L. senegala. Likewise, nestling indigobirds in broods of L. nitidula and L. senegala are similar in having mouth markings that mimic the nestlings of L. senegala rather than those of the novel host. Molecular genetic evidence indicates that the host switch to L. nitidula has involved at least four different indigobird matrilines. Indigobirds that are associated with L. nitidula are genetically similar to the indigobirds associated with sympatric L. senegala, and not to the indigobirds associated with west African Bar‐breasted Firefinch L...

2025

Brood parasitic cuckoos lay their eggs in a host’s nest and thereafter rely completely on their hosts to do their parental care for them. We studied the interactions between four different species of parasitic cuckoos and their three respective hosts in Bangladesh: The Indian Cuckoo Cuculus micropterus parasitised the Black Drongo Dicrurus macrocercus, The Asian Koel Eudynamys scolopaceus, the Long-tailed Shrike Lanius schach, and the Common Hawk Cuckoo Hierococcyx varius, and Pied Cuckoo Clamator jacobinus, the Jungle Babbler Turdoides striata. The breeding seasons of the Black Drongo, and Long-tailed Shrike, started in late March and ended in July, which coincided with those of the Indian Cuckoo (late April–early June), and Asian Koel (March–July), respectively. The Jungle Babbler started breeding in late February, continuing up to June. Competition between its two brood parasites appeared minimal because of their non-overlapping breeding seasons: March–May for the Common Hawk Cuc...

2025, Evolutionary Ecology

Avian brood parasites usually severely depress the reproductive success of their hosts, yet many host species, including those presumably capable of ejecting parasitic eggs, accept them. Female, broodparasitic, Brown-headed Cowbirds typically remove a host egg when they lay their own and damage some host eggs in the process of ejecting a host egg. Data from a field study of Red-winged Blackbirds show that these costs, which cannot be avoided by ejecting the parasitic egg, account for some of the reproductive losses attributable to parasitism, but part is due to the presence of the cowbird egg in the nest. To assess whether ejection would be favoured under current circumstances, the probable damage a female Redwing could cause to her own eggs by attempting to eject a cowbird egg needs to be determined.

2025, USGS Professional Paper

Keys to Field Sparrow (Spizella pusilla) management include providing shrub-dominated edge habitat adjacent to grasslands or grasslands with a shrub component (both of which must include dense grass and moderately high litter cover) and avoiding disturbances that eliminate woody vegetation. Field Sparrows have been reported to use habitats with 16–134 centimeters (cm) vegetation height, 20–145 cm visual obstruction reading (VOR), 17–90 percent grass cover, 2–45 percent forb cover, less than (<) 63 percent shrub cover, 3–7 percent bare ground, 14–30 percent litter cover, and 1–7 cm litter depth.

2025, Animal Cognition

In birds, the colour, maculation, shape, and size of their eggs play critical roles in discrimination of foreign eggs in the clutch. So far, however, no study has examined the role of egg arrangement within a clutch on host rejection responses. We predicted that individual females which maintain consistent egg arrangements within their clutch would be better able to detect and reject foreign eggs than females without a consistent egg arrangement (i.e. whose eggs change positions more often across incubation). We tested this ''egg arrangement hypothesis'' in blackbirds (Turdus merula) and song thrush (T. philomelos). Both species are suitable candidates for research on egg rejection, because they show high inter-individual variation and individual repeatability in egg rejection responses. As predicted, using our custom-defined metrics of egg arrangement, rejecter females' clutches showed significantly more consistent patterns in egg arrangement than acceptor females' clutches. Only parameters related to blunt pole showed consistent differences between rejecters and acceptors. This finding makes biological sense because it is already known that song thrush use blunt pole cues to reject foreign eggs. We propose that a disturbance of the original egg arrangement pattern by the laying parasite may alert host females that maintain a consistent egg arrangement to the risk of having been parasitized. Once alerted, these hosts may shift their discrimination thresholds to be more restrictive so as to reject a foreign egg with higher probability. Future studies will benefit from experimentally testing whether these two and other parasitized rejecter host species may rely on the use of consistent egg arrangements as a component of their anti-parasitic defence mechanisms.

2025, The Wilson Journal of Ornithology

2025, Revista catalana d'ornitologia = Catalan journal of ornithology

One of the major challenges of the coevolutionary theory is to understand the spatio-temporal dynamic of the infection processes and the evolution of defenses and counter-defenses between parasites and their hosts. A number of abiotic and biotic factors that can vary spatiotemporally may indirectly or directly affect the dynamic of the interaction. Avian brood parasites and their hosts provide an ideal system for the study of coevolution and in particular, the great spotted cuckoo (Clamator glandarius) and its main host in the Iberian Peninsula, the magpie (Pica pica), constitutes a suitable system for studying these issues. This system has provided strong support for an effect of brood parasitism on (1) the reproductive success of the host and ( ) on the evolution of host defensive mechanisms counteracting the negative effects of parasitism. However long-term studies with marked animals addressing issues related to patterns of host use by parasites, and defense mechanisms, are very scarce in general, and indeed nonexistent for this system. This thesis analyzes in a first block, through cross-sectional and longitudinal studies (based on resampling known individuals in different breeding seasons), the patterns of parasitism in the population. In a second block, through longitudinal studies, questions related to the evolution of defensive mechanisms against parasitism along the life of individual hosts are addressed. The results of this thesis suggest that the pattern of parasitism, at the population level, respond to a probabilistic process based on the spatialtemporal availability of magpie nests and the abundance of cuckoos in the population. In addition, it has been found that the population phenological mismatch between great spotted cuckoos and magpies changes between seasons depending on climatic factors, thus providing an additional explanation to the found annual variation in the probability of parasitism. Also, a longitudinal study reveals a pattern of structured parasitism at the individual level within the population. Indeed, females with a particular combination of traits (nest size, laying date and habitat characteristics) consistently escaped from cuckoo parasitism.

2025, Animal Behaviour

One of the most effective defensive strategies of hosts against brood parasites is rejection, commonly achieved by ejection of the parasitic egg or desertion of the parasitized nest. Nest desertion should be a costlier strategy than egg ejection because birds then must spend additional time and energy re-nesting, and therefore we still cannot explain why some individuals desert their nests rather than eject parasitic eggs and continue a given breeding attempt. The great reed warbler (Acrocephalus arundinaceus) is a frequent host of the common cuckoo (Cuculus canorus) and is known to use both types of rejection response. We investigated the hypothesis that the hosts desert if they cannot reliably recognize the cuckoo egg in their nest by measuring cuckoo egg mimicry. We predicted that we would find better mimicry when hosts deserted rather than ejected. However, we did not find a difference in mimicry between these two groups of nests, implying that host females do not desert because they cannot reliably recognize the parasitic egg. We also showed that neither the date in the season nor the age of the host females influences the type of the rejection. Other factors potentially eliciting nest desertion, including host personality, host, inability to eject, excessive clutch reduction and visibility of the cuckoo female at the host nest are discussed. Finally, we suggest that desertion may persist as a host defensive strategy against brood parasitism because it is not as costly as previously assumed and/or it is beneficial for host females in good physical condition.

2025, Ecological Entomology

1. The nests of solitary, nest-provisioning wasps (Sphecidae and Crabronidae) are commonly attacked by brood parasites, including flies of the families Phoridae and Sarcophagidae. Larvae of the flies commonly kill the wasp offspring directly or starve it by consuming prey provided by the adult female wasps. 2. To determine whether brood parasitic flies can have a sublethal effect (i.e. reduced body size) on wasp offspring, nests of the wasp Isodontia mexicana were collected at two field sites in upstate New York, U.S.A. Nest diameter had no effect on the probability that a wasp cell would be inhabited by a brood parasite. Most offspring that developed in cells also containing phorids or sarcophagids managed to complete development and emerge as adults. Nevertheless, they had significantly smaller body size than conspecifics emerging from unparasitised cells in which the developing wasp did not have to compete for food (which in this species consists of tree crickets and katydids). Apparently, this is the first time that a sublethal effect of brood parasitism on offspring body size has been quantified for a solitary wasp species. Known effects of body size on the reproductive success of adult wasps suggest that sublethal consequences of the presence of brood parasites may have a significant effect on the fitness of adult I. mexicana .

2025, Annales Zoologici Fennici

Rejection of parasitic eggs is one of the most important adaptations of avian hosts against brood parasites. Multiple brood parasitism is relatively rare in hosts of the common cuckoo (Cuculus canorus), but naturally occurs when the rate of parasitism is high. We experimentally parasitised great reed warbler (Acrocephalus arundinaceus) clutches with non-mimetic and moderately mimetic model cuckoo eggs. In the case of single parasitism, each egg type was rejected at the same rate (68%-75%), but in the case of multiple parasitism, the rejection rate significantly increased to 96%. So multiple parasitism is in some way facilitating anti-parasite behaviour in the host. We suggest that when parasitism rate reaches high levels, e.g. at the beginning of the coevolutionary arms race, multiple parasitism may be an important component of the host's adaptation to brood parasitism in general.

2025, Journal of Zoology

Common cuckoos (Cuculus canorus) are obligate brood parasites that lay their eggs in the nests of other (host) species. To increase the likelihood of successful parasitism, common cuckoos lay eggs with thicker and structurally stronger eggshells than those of their hosts and non-parasitic relatives. Although hatching from thicker eggshells requires greater effort and may impose physiological costs on cuckoo embryos during hatching, it is unclear whether cuckoo eggshells are indeed thicker at the time of hatching. This is because avian embryos decalcify the innermost eggshell layer (mammillary layer) for organ development during embryogenesis, reducing eggshell thickness and making hatching easier. Therefore, common cuckoo eggshells may undergo a greater degree of decalcification during embryonic development to facilitate hatching from an initially thicker-shelled egg. We used scanning electron microscopy to test this hypothesis by comparing the thickness and degree of decalcification of eggshells collected either before incubation or after hatching. We found that cuckoo eggshells undergo similar degrees of decalcification during embryonic development as the thinner eggshells of a host that lays similarly sized eggs, the great reed warbler (Acrocephalus arundinaceus). Cuckoo eggshells hence remain thicker than eggshells of this host throughout embryogenesis, supporting the predicted trade-off between the benefits of laying puncture resistant eggs and the physiological costs associated with hatching.

2025, Population Ecology

Avian brood parasites greatly reduce the reproductive success of their hosts. Empirical studies have demonstrated that some hosts have evolved defenses against parasitism like an ability to recognize and reject parasitic eggs that are dissimilar to their own eggs. Detailed mechanisms of how hosts recognize parasitism still remain unknown, but recent studies have shown that the host's recognition, in many cases, is based on discordance of the eggs in a clutch, and that hosts are more errorprone when the nest is multiply parasitized, i.e., hosts tend to accept more multiple parasitism than single parasitism. In an area in Hungary, the great reed warbler Acrocephalus arundinaceus, one of the main hosts of the common cuckoo Cuculus canorus, is heavily parasitized and the parasitism rate has been kept at quite a high level for decades. Previous mathematical models suggest that such a high parasitism rate can be maintained because the focal host population behaves as a sink where few hosts can reproduce but immigration from outside replenishes the loss of host reproduction in the sink population. Here, we explore the consequences of the increased host tolerance towards multiple parasitism which has been overlooked in the previous studies using a simple model. Our model analysis shows that the increased host tolerance can dramatically contribute to both the parasite abundance and the parasitism rate being kept at a high level. We suggest that such a host behavior, combined with host immigration, can be an important factor responsible for the observed severe parasitism.

2025, Population Ecology

2025

The nesting biology of the Coot Fulica atra was studied in the Camargue, Rhne river delta in southern France, where wetlands range from salines and brackish lagoons to freshwater marshes. Coots nested only on the latter. Nesting success depended on drying out of the marshes, and vegetative cover of the nests provided some protection against aerial predators. The density of nests was lower in marshes which dried out early. The distribution of nests in the marshes was related to the distribution of emergent vegetation at least 30 cm tall. Nest distribution changed during the reproductive period as the peripheral parts of the marsh dried out and new emergent vegetation grew up. Regular nest checks revealed that nesting started earlier in years with high water levels and on marshes with large areas covered by emergent vegetation. Nesting started first on Phragmites marsh and on tamarisk trees, followed with a delay of 10-20 days on a mixed vegetation of Typha and Scirpus. Nests were bes...

2025, Animal Behaviour

Brood-parasitic village indigobirds, Vidua chalybeata, were bred in captivity and foster-reared by their normal host, red-billed firefinch, Lagonosticta senegala, or by an experimental foster species, Bengalese finch, Lonchura striata. Male indigobirds reared by Bengalese finches developed the songs of Bengalese finches, and males reared by firefinches developed songs of firefinches. Males copied their foster father only when they had lived with him long after independence (45 days post-fledging), while males separated normally at independence (22-24 days post-fledging) copied songs of other individuals and not songs of their foster father. Males reared by Bengalese finches showed no preference to learn firefinch song over songs of the experimental foster species or other control finch species even when they had lived with firefinches as companions from the time of fledging to independence. Males copied several song themes, acquired the same number of mimicry songs, and acquired their songs at the same age, whether reared by Bengalese finches or by firefinches. When they lived with other indigobirds, the male indigobirds copied mimicry songs of male indigobirds that mimicked the same foster species. We predicted mimicry-song specificity and repertoire size in experimental indigobirds from a hypothesis of an early developmental period when young indigobirds focus their attention on their foster parents, and a later period when they direct their attention to other birds with similar songs. The predictions, based on field observations of wild birds, were that (1) males reared by a novel foster species other than the normal host would learn the song of that foster species, and (2) males that left their foster parents at the normal time of independence would copy the songs of other individuals, including other adult indigobirds that mimicked the same foster species. Begging calls of young indigobirds did not mimic the calls of young firefinches. Indigobirds reared alone, or with young of the normal host or of the experimental foster species, all developed begging calls in adult song that resembled their own begging as nestlings and fledglings, and only males that heard other adult indigobirds with firefinch-mimicry begging developed firefinch begging in their song. The incorporation of the innate begging calls as well as the learned begging calls into adult song, and the modification of the song themes of their individual song models, suggest that song development involves processes in addition to copying the songs of their own foster species and of older adult male indigobirds with songs like their own foster parents.

2024, PLOS ONE

The hatching success of a bird's egg is one of the key determinants of avian reproductive success, which may be compromised by microbial infections causing embryonic death. During incubation, outer eggshell bacterial communities pose a constant threat of pathogen translocation and embryo infection. One of the parental strategies to mitigate this threat is the incorporation of maternal immune factors into the egg albumen and yolk. It has been suggested that habitat changes like forest fragmentation can affect environmental factors and life-history traits that are linked to egg contamination. This study aims at investigating relationships between microbial pressure, immune investment and hatching success in two abundant forest bird species and analyzing to what extent these are driven by extrinsic (environmental) factors. We here compared (1) the bacterial load and composition on eggshells, (2) the level of immune defenses in eggs, and (3) the reproductive success between great (Parus major) and blue (Cyanistes caeruleus) tits in Belgium and examined if forest fragmentation affects these parameters. Analysis of 70 great tit and 34 blue tit eggshells revealed a similar microbiota composition (Enterobacteriaceae, Lactobacillus spp., Firmicutes and Bacteroidetes), but higher bacterial loads in great tits. Forest fragmentation was not identified as an important explanatory variable. Although a significant negative correlation between hatching success and bacterial load on the eggshells in great tits corroborates microbial pressure to be a driver of embryonic mortality, the overall hatching success was only marginally lower than in blue tits. This may be explained by the significantly higher levels of lysozyme and IgY in the eggs of great tits, protecting the embryo from increased infection pressure. Our results show that immune investment in eggs is suggested to be a species-specific adaptive trait that serves to protect hatchlings from pathogen pressure, which is not directly linked to habitat fragmentation.

2024, Behavioral Ecology and Sociobiology

Lactation imposes substantial physiological costs on mothers and should therefore not be directed towards foreign offspring. Such allonursing, however, is common in mammal species that share roosts. Hypotheses to explain allonursing among such plural breeders include misdirected parental care, milk evacuation, brood parasitism, reciprocity, and kin selection. The necessary behavioral data, in combination with data on kinship and kin recognition, have rarely been available to distinguish among these explanations, however. In this study, we provide evidence for cooperative nursing and adoption by plural-breeding females in a nocturnal primate, the gray mouse lemur (Microcebus murinus), in which females forage solitarily during the night, but form daytime sleeping groups with one to two other females. We observed 34 resident females in an 8 ha study area in Kirindy Forest, Madagascar, over three consecutive annual breeding seasons and determined genetic relationships among all members of this population. Five sleeping groups of adult females were filmed inside their roosts during one breeding season after females gave birth. The composition of groups changed substantially across years, but they always consisted of close maternal relatives. All females within a group gave birth to one to three infants. They regularly transferred only their own offspring among roosting sites, demonstrating an ability to discriminate between their own and other's offspring, but they regularly groomed and nursed related offspring other than their own and adopted related dependent young after their mother's death. Kin selection may therefore be the main selective force behind cooperative breeding among these closely related females with a high mortality risk, providing each of them with family insurance.

2024, Behavioral Ecology and Sociobiology

2024, Conservation Biology

2024, Western North American Naturalist

The Plumbeous Vireo (Vireo plumbeus) is a poorly studied songbird species that breeds within the interior western United States and Mexico. We studied the breeding behavior of Plumbeous Vireos within pinyon-juniper habitats in northeastern New Mexico in 1996 and 1997. Over both years we located and monitored 40 nests and conducted behavioral observations throughout the nesting cycle. From these observations we described and compared basic behavioral traits of male and female vireos during their nest-building, egg-laying, incubation, and nestling stages, and their response to potential predators near the nest. Male vireos displayed potential nest sites to females, but the females selected the site to be used and built most of the nest. Vireos often did not initiate egg-laying until 2-3 d after nest completion. The female tended to incubate eggs and brood nestlings more than the male, but both parents contributed equally in provisioning the young. Brown-headed Cowbirds (Molothrus ater) parasitized 77% of nests in 1996, 63% in 1997, and parasitism was the primary cause of nest failure in this population. The conspicuousness of vireos around the nest, particularly during the nest-building stage, may contribute to high parasitism levels. Vireo aggression near the nest may also act as a cue to help cowbirds locate nests.

2024, Ornitologia …

Resumen.-Reducción en el uso de hospedero sugiere especificidad de hospedero en individuos de Tordos Lustrosos (Molothrus bonariensis).-La Mariquita de Puerto Rico (Agelaius xanthomus) está en peligro de extinción, principalmente como resultado del parasitismo de camada por el Tordo Lustroso (Molothrus bonariensis). Para mitigar los efectos del parasitismo, se implementó a largo plazo un programa de control de tordos, dirigido a atrapar tordos (tratamiento 1) y remover sus huevos y pichones de los nidos de mariquitas (tratamiento 2). El programa está concentrado en el suroeste de Puerto Rico donde la Mariquita de Puerto Rico y el Canario de Mangle (Dendroica petechia) son los hospederos más importantes. En el área manejada, el porcentaje promedio de parasitismo de camada en nidos de la Mariquita de Puerto Rico y del Canario de Mangle fue de 3 y 42%, respectivamente. En un área de referencia (sin programa), el porcentaje en la mariquita promedió 54% mientras que observamos 85% de los nidos del canario parasitados. El contraste en los porcentajes de parasitismo es sorprendente porque la mariquita fue previamente reconocida como el principal hospedero, y porque los tordos son comunes en el área estudiada. La diferencia en porcientos de parasitismo entre áreas fue atribuida al entrampamiento. Investigamos si el tratamiento 2 pudiera resultar en una reducción del uso del hospedero, aun en abundancia de tordos y nidos del hospedero. Para esto, predijimos que una tasa alta de parasitismo en los nidos de canario, pero baja en los nidos de mariquita, podría sugerir que los resultados no fueron causados exclusivamente por el tratamiento 1; si no, esperaríamos que el entrampamiento tuviera efectos similares en ambos hospederos. Esto deja el tratamiento 2 como el factor ejerciendo influencia en la selección del hospedero, por ende, una prueba apropiada para posible especificidad de hospedero. Nuestros resultados sugieren que el tratamiento 2 redujo significativamente el uso de un hospedero, quizás por no permitir la improntación de la Mariquita de Puerto Rico como hospedero.

2024, Biological Conservation

The yellow-shouldered blackbird, Agelaius xanthomus, is endemic to Puerto Rico and Mona Island, and endangered since 1976 mainly because of brood parasitism by the shiny cowbird, Molothrus bonariensis. In 1984 an artificial nest structures program was initiated, combined with the removal of M. bonariensis, to improve the reproductive success of A. xanthomus. The nesting success was high in artificial nest structures. From 1996 to 1999, 22 out of 804 nests in artificial structures and one of 203 nests in natural substrates were parasitized. The use of natural substrates increased from less than 1% (1996) to 35% (1999). Predation was the main cause of egg and chick loss and was high in natural substrates. The increase in the use of natural substrates for nesting is a trend favorable for the recovery of this species. Continued management is still needed to augment the breeding population and reproductive output.

2024, Redia-Giornale Di Zoologia

Polistes biglumis is a species that in Southern Europe lives at high altitude where generally cold temperatures exert a selective pressure. Colonies of P. biglumis may be parasitized by the obligate and permanent social parasite P. atrimandibularis and suffer a drastic reduction in fitness. Locally, parasite prevalence is high and parasitism costs to hosts are elevated; under these conditions hosts are selected to evolve counter-adaptations against parasites. Comparing the behaviour of P. biglumis females from three populations under different combinations of selective pressures (cold temperature and social parasitism) we show how different selective pressures operate and differentiate the life cycle and behaviour of local populations.

2024, Behavioral Ecology

Behavioral ecology has successfully explained the diversity in sodal mating systems through differences in environmental conditions, but diversity in genetic mating systems is poorly understood. The difference is important in situations where parents care for extrapair young (EPY) originating from extrapair paternity (EPP), extrapair maternity (EPM), and intraspedfic brood parasitism (IBP). In birds, IBP and EPM are rare, but EPP is widespread and highly variable among species and populations. Explanations for this variability are controversial, mainly because detailed ecological information is usually lacking in paternity studies. Here we present results of the first study to identify the ecological determinants of extrapair activities for both sexes of the same species, the water pipit {Anthus spinoUtta). DNA fingerprints of 1052 young from 258 nests revealed EPP in 5.2% of the young from 12.4% of the nests. EPM and IBP, both involving egg dumping (EDP), each occurred in 0.5% of the young from 1.9% of the nests. Nests with and without EPY could not be distinguished by traits of the breeders and by reproductive succcess, but they differed with respect to ecology: nests with EPP young were characterized by asynchronous clutch initiation, nests with EPM and IBP young were characterized by higher overlap with neighboring territories and closer proximity to communal feeding sites. We suggest that chance events, resulting from the temporaTand spatial distribution of broods, offer a better explanation for the occurence of extrapair activities than female search for genetic or phenotypic benefits. This possibility of "accidental" extrapair reproduction as an "ecological epiphenomenon" with low potential for selection should also be considered for species other than the water pipit Kty words: Anthus spinolttia, breeding synchrony, DNA fingerprinting, extrapair maternity, extrapair paternity, intraspedfic brood parasitism, mating system, operational sex ratio, territory overlap, water pipit. [Bthav Ecol 8:534-543 (1997)] D knowledge about the evolution of mating systems XT and sex-specific parental care is largely based on comparing social associations between males and females under different ecological conditions (Davies, 1991; Emlen and Oring, 1977; Oring, 1982; Reyer, 1994b; Wittenberger, 1979). Social bonds, however, do not necessarily reflect mating combinations and parentage (Gowaty, 1985; Wickler and Seibt, 1983). For example, in many bird spedes parents care for extrapair young (EPY). These young can originate from extrapair paternity (EPP), extrapair maternity (EPM) and intraspedfic brood parasitism (IBP). The former two patterns result from extrapair copulations (EPC) of males and females with individuals other than their social mat**, and the latter two result from egg dumping (EDP)-Le., females laying in foreign nests (Birkhead and M«ller, 1992; Petrie and Mailer, 1991). While EPM and IBP are infrequent (reviewed by Andersson, 1984; MacWhirter, 1989; Reyer, 1994a; Yom-Tov, 1980; see also Hartley et aL, 199S), EPP is widespread and highly variable among spedes and populations, affecting between 0% and 60% of nests and young (Birkhead and Miller, 1992). It is generally agreed that this variability reflects individual-, sex-, spedes-, and environment-«pedfic differences in the trade-off between the benefits from pursuing extrapair activities and the costs from "neglecting" one's own mate, nest, or dependent young (reviews by Birkhead and Mailer, 1992; Kempenaers and Dondt, 1993; Petrie and Meller, 1991; Wesmeat et aL, 1990). But how phenotypic and ecological factors influence extrapair activities and which sex is in control is disputed

2024, Behavioral Ecology

Social parasitism is an intriguing model of arms-race coevolution, in which the parasite exploits the host social system. The parasite evolves to breakdown the host's defenses. We analyzed the role of 2 pseudoscorpion species that live in mixed colonies in the Brazilian Cerrado (tropical savannah). Multispecies aggregation is a rare phenomenon among arachnids. Mixed pseudoscorpion colonies were studied in nature and in the laboratory during a period of 7 years and the hypothesis of a relationship based on social parasitism between species was evaluated, including the main strategies involved. Experiments and direct behavioral observations indicated that the pseudoscorpion Parachernes melanopygus is a social parasite of Paratemnoides nidificator, able to invade host colonies and exploit their resources by simulating host nymphs' behavior. Although the host species has a recognition system, the parasite evades colony defenses by using a chemical camouflage mechanism. We find support for the hypothesis of a new model of social parasitism among phylogenetically distant pseudoscorpion species. To survive in the host colony, the parasite applies a combination of strategies, previously observed in social brood parasite ants and birds. This phenomenon provides new knowledge of the Arachnida group and also for known models of social parasitism.

2024, Behavioral Ecology

It has been suggested that discrimination and rejection of the nestlings of avian brood parasites are most likely to evolve when the parasite nestling is raised alongside the host nestlings, for example, many cowbird-host systems. Under these circumstances, the benefits of discrimination are high because the host parents may save most of their brood. However, there is a general absence of nestling rejection behavior among hosts of nonevicting parasites. In a cost-benefit equilibrium model, based on the premise that host species learn to recognize their offspring through imprinting on first breeding, we show that nestling recognition can be adaptive for hosts of cowbirds, but only under strict conditions. Namely, when host nestling survival alongside the parasite is low, rates of parasitism are high and the average clutch size is large. All of these conditions are seldom simultaneously achieved in real systems. Most importantly, the parasite nestling, on average, does not sufficiently depress host nestling survival to outweigh the costs of nestling recognition and rejection errors. Thus, we argue that nestling acceptance behaviors by hosts of nonevicting brood parasites may be explained as an evolutionary equilibrium in which recognition costs act as a stabilizing selection pressure against rejection when most of the host's offspring survive parasitism.

2024, Central Valley Birds

The Least Bell's Vireo (Vireo bellii pusillus) is federally and state listed as Endangered in the U.S. and California and has been recommended for downlisting to Threatened by the U.S. Fish and Wildlife Service. This taxon, once abundant in the Central Valley of California, was extirpated from this region by the middle of the 20 th century. Since its listing in the 1980s, the subspecies has been increasing at many southern California locations. Beginning in the early part of the 21 st century Least Bell's Vireos began appearing at sites in the Central Valley and surrounding foothills in the breeding season and these observations have continued. To update the status and distribution of the Least Bell's Vireo in its historical Central Valley center of abundance, I reviewed all available reports of breeding season observations of this taxon from 2004 through 2024. These reports indicate that establishment of a breeding population has not occurred but suggest that re-establishment of a breeding population within this region may be feasible. Suggested specific actions could facilitate this reestablishment.

2024, Behavioral Ecology

Although heterospecific vocal imitation is well documented in passerines, the evolutionary correlates of this phenomenon are poorly known. Here, we studied interspecific variation in vocal mimicry in a comparative study of 241 European songbirds. We tested whether vocal mimicry is a mode of repertoire acquisition or whether it resulted from imperfect song learning. We also investigated the effect of the degree of contact with the vocal environment (with species having larger ranges, abundance, or being long lived having a higher degree of mimicry) and a possible link with cognitive capacity (an overall larger brain in species with mimicry). Finally, we determined the potential evolutionary role of vocal mimicry in different interspecific contexts, predicting that mimicry may affect the intensity of brood parasitism, predation, or degree of hybridization. While controlling for research effort and phylogenetic relationships among taxa, we found that effect sizes for intersong interval, brain size, breeding dispersal, abundance, age-dependent expression of repertoires, and predation risk reached a level that may indicate evolutionary importance. Vocal mimicry seems to be a consequence of song continuity rather than song complexity, may partially have some cognitive component but may also be dependent on the vocal environment, and may attract the attention of predators. However, estimates of sexual selection and interspecific contacts due to brood parasitism and hybridization varied independently of vocal mimicry. Therefore, mimicry may have no function in female choice for complex songs and may be weakly selected via interspecific associations. These findings provide little evidence for vocal mimicry having evolved to serve important functions in most birds.

2024, Behavioral Ecology

2024, Insectes Sociaux

Alchisme grossa is a treehopper species showing maternal care until at least the third nymphal instar. A secondary female treehopper has frequently been observed near a family (primary female guarding its egg clutch). Intraspecific brood parasitism, communal breeding or alloparental care may be suggested as possible mechanisms to explain secondary female presence. To distinguish between these phenomena, we performed relatedness analyses of genetic samples of groups including one A. grossa primary female, a secondary female and the associated offspring using polymorphic microsatellites. Furthermore, we characterized the behavioral interaction between both females during maternal care and the reproductive strategy (monandry or polyandry) of A. grossa females by estimating the number of male parents. We observed the presence of secondary females in 35.9% of monitored families. The behaviors characterized suggest the occurrence of brood parasitism in the interaction between both females. Nevertheless, all offspring within a family were descendants only of the primary female and a single male, thus showing that A. grossa females are monandrous. The results, taken together with data on the reproductive biology reported for other treehoppers, are consistent with the occurrence of brood parasitism in A. grossa.

2024, Atlantis Revista De La Asociacion Espanola De Estudios Anglo Norteamericanos

2024, Journal of Ornithology

We have investigated genetic parentage in a Swiss population of tawny owls (Strix aluco). To this end, we performed genetic analysis for six polymorphic loci of 49 avian microsatellite loci tested for crossspecies amplification. We found one extra-pair young out of 137 (0.7%) nestlings in 37 families (2.7%). There was no intra-specific brood parasitism. Our results are in accordance with previous findings for other raptors and owls that genetic monogamy is the rule. Female tawny owls cannot raise offspring without a substantial contribution by their mates. Hence one favoured hypothesis is that high paternal investment in reproduction selects for behaviour that prevents cuckoldry.

2024, The ISME Journal

Gut microbiota are essential for host health and survival, but we are still far from understanding the processes involved in shaping their composition and evolution. Controlled experimental work under lab conditions as well as human studies pointed at environmental factors (i.e., diet) as the main determinant of the microbiota with little evidence of genetic effects, while comparative interspecific studies detected significant phylogenetic effects. Different species, however, also differ in diet, feeding behavior, and environmental characteristics of habitats, all of which also vary interspecifically, and, therefore, can potentially explain most of the detected phylogenetic patterns. Here, we take advantage of the reproductive strategy of avian brood parasites and investigate gut microbiotas (esophageal (food and saliva) and intestinal) of great spotted cuckoo (Clamator glandarius) and magpie (Pica pica) nestlings that grow in the same nests. We also estimated diet received by each nestling and explored its association with gut microbiota characteristics. Although esophageal microbiota of magpies and great spotted cuckoos raised within the same environment (nest) did not vary, the microbiota of cloacal samples showed clear interspecific differences. Moreover, diet of great spotted cuckoo and magpie nestlings explained the microbiota composition of esophageal samples, but not of cloaca samples. These results strongly suggest a genetic component determining the intestinal microbiota of host and parasitic bird species, indicating that interspecific differences in gut morphology and physiology are responsible for such interspecific differences.

2024, Oecologia

Certain kinds of hosts are commonly regarded as being more suitable than other for rearing European cuckoos (Cuculus canorus) ± insectivores that lay small eggs and have open, shallow nests ± although empirical tests of cuckoo host selection are lacking. We analysed host use by the European cuckoo in 72 British passerines that are potential hosts and for which there was information available on life-history variables and variables related to cuckoo-host coevolution, such as rate of parasitism, rejection rate of non-mimetic model eggs and degree of cuckoo-egg mimicry of host eggs. The relative population size of the host species aected parasitism rate most strongly, followed by relatively short duration of the nestling period, and the kind of nest, with cuckoos selecting open-nesting hosts. However, the eect of the nestling period could be related to host body size and the kind of nest used, because hole-nesting species normally have longer nestling periods than open-nesters. We re-analysed the data excluding hole nesters and corvid species (species with larger body mass), but the results remained identical. The European cuckoo may bene®t from selecting hosts with short nestling periods because such hosts provide food for their nestlings at a very high rate. When only those species known as cuckoo hosts were analysed, the variable that best accounted for the parasitism rate was duration of the breeding season. Therefore, availability of potential hosts in both time and space is important for cuckoos in selecting hosts.

2024, Behavioral Ecology and Sociobiology

When brood parasites are about to lay an egg, they have to decide which nest to parasitize. The best nest in which to lay will depend on the parenting ability of the host. We have studied selection of magpie