Egg Predation Research Articles

Snake predators of bird eggs: a review and bibliography

Snake predators of bird eggs: a review and bibliography

Chemical Ecology of the North American Newt Genera Taricha and Notophthalmus.

The North American newt genera Taricha and Notophthalmus (order Caudata) are well known for the combination of potent toxicity, aposematic coloration, and striking defense postures that protects these animals from predation. This suite of traits is centered around the neurotoxin tetrodotoxin, which causes paralysis and death in metazoans by disrupting the initiation and propagation of electrical signals in the nerves and muscles. Tetrodotoxin defends newts from predation across multiple life history stages and its role in generating arms-race coevolution between Taricha newts and garter snake (genus Thamnophis) predators is well studied. However, understanding the broader picture of chemical defenses in Taricha and Notophthalmus requires an expanded comprehension of the defensive chemical ecology of tetrodotoxin that includes possible coevolutionary interactions with insect egg predators, protection against parasites, as well as mimicry complexes associated with tetrodotoxin and aposematic coloration in both genera. Herein the authors review what is known about the structure, function, and pharmacology of tetrodotoxin to explore its evolution and chemical ecology in the North American newt. Focus is made specifically on the origin and possible biosynthesis of tetrodotoxin in these taxa as well as providing an expanded picture of the web of interactions that contribute to landscape level patterns of toxicity and defense in Taricha and Notophthalmus.

Fishing, predation, and temperature drive herring decline in a large marine ecosystem.

Since 1960, landings of Atlantic herring have been the greatest of any marine species in Canada, surpassing Atlantic cod and accounting for 24% of the total seafood harvested in Atlantic Canada. The Scotian Shelf‐Bay of Fundy herring fisheries (NAFO Division 4VWX) is among Canada's oldest and drives this productivity, accounting for up to 75% of the total herring catch in some years. The stocks’ productivity and overall health have declined since 1965. Despite management measures to promote recovery implemented since 2003, biomass remains low and is declining. The factors that drive the productivity of 4VWX herring are primarily unresolved, likely impeding the effectiveness of management actions on this stock. We evaluated potential drivers of herring variability by analyzing 52 time‐series that describe the temporal and spatial evolution of the 4VWX herring population and the physical, ecological, and anthropogenic factors that could affect them using structural equation models. Variation in herring biomass was best accounted for by the exploitation rate's negative effect and the geographic distribution of fishing and recruitment. Thermal phenology and temperature adversely and egg predation positively impacted the early life stage mortality rate and, ultimately, adult biomass. These findings are broadly relevant to fisheries management, but particularly for 4VWX herring, where the current management approach does not consider their early life stage dynamics or assess them within the ecosystem or climate change contexts.

Comparative Morphology and Morphometric Analysis of Some Histeridae (Insecta: Coleoptera) Species

Histeridae (Coleoptera) is a worldwide group of about 400 genera and 4500 species. Many family members are predators of eggs, larvae, and adults of Diptera (Insecta) species. On the other hand, rotting corpses have great precaution in forensic studies due to their feeding and colonization. The taxonomic characters used in the classification of Histeridae species are based on morphology. However, the variations in morphological characters cause difficulties in the determinations that lead to significant errors in the diagnostic process. In this study, seasonal variations of some Histeridae species used to determine the minimum time of death (PMI) in forensic investigations are evaluated with geometrical morphometry and the references given for the prevention of errors for identifying species.

Armoured bush cricket, Acanthoplus discoidalis (Walker) (Orthoptera: tettigoniidae) outbreak prediction using rainfall patterns in three zones of Botswana

Based on a quantitative understanding of the environmental factors effecting armoured bush cricket, Acanthoplus discoidalis population dynamics, a hypothesis was formulated to explain the occurrence of outbreaks in some years and locations. The principles, expressed using a rule-based or qualitative model, were that nymph and adult survival and fecundity were reduced in years with uneven rainfall and that egg survival was reduced in years with a wet late-season as this is associated with increased egg predation and/or water-logging. The implication was that large egg banks resulted either when a large number of adults were present or when neither low fecundity nor high egg mortality were constraints. Such large egg banks were however predicted only to lead to outbreaks when there was an adequate amount of food for nymph and adult survival in the following season. Model predictions were compared with observed outbreaks of A. discoidalis between 1988 to 2002 for the three climatic zones of the east, central and western parts of southern Botswana. There was significant agreement between model predictions and observed outbreaks in two of the three zones (95% confidence interval of the kappa coefficient of agreement > 0). Taking the data for all three zones together and compared to the average outbreak frequency, an outbreak was three times more likely to occur when the model predicted an outbreak and six times less likely to occur when it predicted no outbreak.

Pollen Feeding Reduces Predation of Northern Corn Rootworm Eggs (Coleoptera: Chrysomelidae, Diabrotica barberi) by a Soil-Dwelling Mite (Acari: Laelapidae: Stratiolaelapsscimitus).

Simple SummaryFlowering plants are used to enhance pest control by predators and parasitoids, but insect herbivores can also use floral resources. We documented the species of adult rootworm beetles on key plants, and found that northern corn rootworm (NCR) adults were commonly associated with sunflower inflorescences while western corn rootworm adults were most abundant in corn and on squash blossoms. Consumption of sunflower and corn pollen by NCR adults did not impact predation of their eggs by an omnivorous mite, but a predatory soil-dwelling mite ate pest eggs less frequently and took longer to feed on eggs when NCR adults had fed on sunflower pollen. While increasing plant diversity can benefit natural enemies and pest control within agroecosystems, it is important to consider how floral resources alter dietary preferences of biocontrol agents.Landscape diversification with flowering plants can benefit pollinators and natural enemies, although insect pests can also use floral resources for nutrition and chemoprotection. Corn rootworms (Coleoptera: Chrysomelidae, Diabrotica spp.) are major pests of corn (Zea mays L.), and while subterranean larvae primarily feed on corn roots, adult rootworms commonly consume floral resources from other plant species. We quantified the species, density, and sex of adult corn Diabroticite rootworm beetles on wild and cultivated sunflower, corn, and squash, quantified pollen within the bodies of adult northern corn rootworms [NCR, D. barberi (Smith & Lawrence)], and investigated how consumption of sunflower and corn pollen by NCR adults impacted predation of their eggs by two soil-dwelling mites with different feeding specialization. NCR were the most common Diabroticite species on sunflower inflorescences and western corn rootworm (WCR, D. v. virgifera LeConte) were more abundant in corn and squash blossoms. Pollen feeding by NCR adults did not impact egg predation by omnivorous Tyrophagus putrescentiae (Schrank) (Acari: Sarcoptiformes, Acaridae), but predatory Stratiolaelaps scimitus (Womersley) (Acari: Mesostigmata, Laelapidae) ate eggs less frequently and took longer to feed on eggs from NCR females that had fed on sunflower pollen. This research suggests pollen feeding by adult NCR can impact predation of their eggs. While increasing plant diversity can benefit natural enemies and pest control within agroecosystems, it is important to consider how floral resources alter dietary preferences of biocontrol agents.

New insights into predation through imaging

ABSTRACT The role of generalist predators has long been considered an important component of mortality for many agricultural pests but can be difficult to quantify. We present the use of digital imaging as a means of both identifying key stink bug egg predators and measuring their relative impact on egg survivorship. Brown marmorated stink bug (BMSB), Halyomorpha halys and bagrada bug, Bagrada hilaris, two exotic stink bugs new to California, are now widely distributed throughout the state. A survey was conducted to identify resident natural enemies of their eggs. A field camera aided in the identification of arthropods attacking these eggs and their relative impact. Predation of BMSB eggs, which are naturally oviposited onto plant foliage, was less than for eggs of bagrada bug, which oviposit onto and into soil. The top ranked predators of BMSB eggs were the carabid Laemostenus complanatus (Coleoptera) the European earwig Forficula auricularia and ring-legged earwig Euborellia annulipes (Dermaptera), the oriental cockroach Blatta orientalis (Orthoptera), and the spider Trachelas spp. (Araneae). The two most common and important predators of bagrada bug were two ant species (Formicidae), Solenopsis xyloni and Monomorium ergatogyna, and species of Collembola (Entomobryidae). A Predation Index was developed to compare the relative importance of BMSB egg predators. Lastly, two striking, unanticipated results are reported: an apparent synergistic interaction between the spider Trachelas spp. and native ant M. ergatogyna in causing damage to sentinel eggs of BMSB, and the predaceous role for Collembola on bagrada bug sentinel eggs.

Novel observations of capelin (Mallotus villosus) spawning directly on a brown algae species (Desmarestia viridis) in coastal Newfoundland, Canada

Capelin (<em>Mallotus villosus</em>) is a key forage fish species within its circumpolar range. This species’ importance lies in its role in the typical marine ‘wasp-waist’ food web, where capelin acts as a conduit for energy flow from lower to higher trophic levels. Herein we describe a novel observation of capelin spawning subtidally on an annual brown algae species, <em>Desmarestia viridis</em>, during July–August 2019 in Placentia Bay, Newfoundland, Canada. Based on extensive video surveys of the seabed along with shoreline surveys and sediment sampling, we did not find other nearby sites with typical capelin subtidal and intertidal spawning habitat (i.e. medium sand to pebble gravel). Findings suggest that capelin spawned directly on this brown algae species, <em>D. viridis</em>. Eggs adhered to <em>D. viridis</em> developed normally and hatched successfully. As temperatures of intertidal areas are predicted to increase above temperatures suitable for capelin egg rearing (2–12°C) with climate change, <em>D. viridis</em> may become a high-quality subtidal spawning habitat for capelin and other fish species. In support, this algal species is adapted to colonize high disturbance areas, allowing protection from egg predators in a high flow environment while also being resistant to urchin grazing.

Nest predator identity and nest predation rates of three songbirds in the Central Andes of south temperate Argentina

Nest predation is the primary cause of nest failure in passerines. In order to contribute to our understanding of how nest predators shape avian nesting ecology and life history traits, we report nest predator identity and nest predation rates for 3 species of passerines in the Central Andes of south temperate Argentina. We used video cameras and opportunistic observations with photographic documentation to identify nest predators of Grass Wrens (Cistothorus platensis) breeding in a riparian grassland, as well as House Wrens (Troglodytes aedon) and House Sparrows (Passer domesticus) breeding in nest boxes in a tree plantation. From 13 nest predation events we were able to identify 3 nest predator species: mousehole snake (Philodryas trilineata), South American gray fox (Lycalopex griseus), and American Kestrel (Falco sparverius). Field observations also suggested fire ants (genera Solenopsis) as a possible nest predator. Mousehole snakes were identified at both grassland and forest plantation, representing 76.9% of the identified predation events. House Sparrows had the highest nest predation rate (43.1%), followed by Grass Wrens (30.8%) and House Wrens (29.3%). Egg predation was more frequent for House Wrens (64.2%) and House Sparrows (50.0%) than for Grass Wrens (22.1%). In contrast, nestling predation was considerably higher for Grass Wrens (77.9%) than for House Wrens and House Sparrows (34.7% and 50.0%, respectively). Knowledge of the nest predator community and information of nest predation rates of different species in temperate South America will contribute to understand nest predation effects on patterns and processes of nesting success, life history traits, and future management decisions in this region.

Group intrusions by a brood parasitic fish are not cooperative

Abstract Brood parasites relegate all parental duties to unrelated hosts. Host resistance against brood parasitism is most effective during egg laying and is best countered by surreptitious oviposition. This may be aided through distraction of host attention by the male partner or a larger cooperative group. Cuckoo catfish (Synodontis multipunctatus) parasitize the broods of mouthbrooding cichlids, which collect their eggs immediately after oviposition. Cuckoo catfish must time their intrusion precisely, as the temporal window for parasitism lasts only a few seconds. As the cuckoo catfish typically intrude host spawning as a group, we tested whether groups of catfish distract spawning cichlid pairs more successfully than a single catfish pair. We found that larger catfish groups were not more effective in parasitism, as parasitism success by groups of three catfish pairs increased only proportionally to single catfish pairs. The number of cichlid eggs in host clutches decreased at high catfish abundance, apparently due to elevated cuckoo catfish predation on the eggs. Hence, group intrusions do not represent cooperative actions, but incur an increased cost to the host cichlid from greater egg predation by cuckoo catfish.

Combination of generalist predators, Nesidiocoris tenuis and Macrolophus pygmaeus, with a companion plant, Sesamum indicum: What benefit for biological control of Tuta absoluta?

Tuta absoluta is one of the most damaging pests of tomato crops worldwide. Damage due to larvae may cause up to 100% loss of tomato production. Use of natural enemies to control the pest, notably predatory mirids such as Nesidiocoris tenuis and Macrolophus pygmaeus, is increasingly being promoted. However, considering the potential damage caused to tomatoes by these omnivorous predators in the absence of T. absoluta, an alternative solution could be required to reduce tomato damage and improve the predators’ performance. The use of companion plants can be an innovative solution to cope with these issues. The present study aimed to determine the influence of companion plants and alternative preys on the predators’ performance in controlling T. absoluta and protecting tomato plants. We evaluated the effect of predators (alone or combined) and a companion plant (sesame (Sesamum indicum)) on T. absoluta egg predation and crop damage caused by N. tenuis. The influence of an alternative prey (Ephestia kuehniella eggs) on the spatial distribution of predators was also evaluated by caging them in the prey presence or absence, either on tomato or sesame plants or on both. We found that the presence of sesame did not reduce the efficacy of N. tenuis or M. pygmaeus in consuming T. absoluta eggs; hatched egg proportion decreased when N. tenuis, M. pygmaeus, or both predators were present. More specifically, this proportion was more strongly reduced when both predators were combined. Sesame presence also reduced necrotic rings caused by N. tenuis on tomato plants. Nesidiocoris tenuis preferred sesame over tomato plants (except when food was provided only on the tomato plant) and the upper part of the plants, whereas M. pygmaeus preferred tomato to sesame plants (except when food was provided only on the sesame plant) and had no preference for a plant part. Combination of predators N. tenuis and M. pygmaeus allows for better coverage of cultivated plants in terms of occupation of different plant parts and better regulation of T. absoluta populations. Sesamum indicum is a potential companion plant that can be used to significantly reduce N. tenuis damage to tomatoes.

Location probing by males complicates sexual dynamics and successful mate‐guarding in squid groups

Reproductive fitness is defined by the successful passing of an individual's genes to the next generation. Cephalopods that mate in groups, in particular coastal squid and cuttlefish species, have evolved complex sexual tactics in order to maximize reproductive success (Morse and Huffard 2019). Through dynamic skin patterning accompanied by typical body postures, individuals send visual signals in the form of displays to potential mates and rival competitors, often engaging in escalating conflicts (Moynihan and Rodaniche 1982, Mather 2016).

Breeding Biology of Chakoor partridge (Alectoris chukar) in Bajaur, Khyber-Pakhtunkhwa, Pakistan: Critically affected by eggs collection and predation

Breeding Biology of Chakoor partridge (Alectoris chukar) in Bajaur, Khyber-Pakhtunkhwa, Pakistan: Critically affected by eggs collection and predation

The Evolution of Social Behaviour

The Evolution of Social Behaviour

Oophagy in the Smooth snake Coronella austriaca – first photographic record of bird egg predation

Oophagy in the Smooth snake Coronella austriaca – first photographic record of bird egg predation

Cowards or clever guys: an alternative nest defence strategy employed by shrikes against magpies.

Red-backed shrikes (Lanius collurio) show a substantial variability in their nest defence behaviour, which usually follows the rules of optimal parental behaviour, vigorously attacking egg and chick predators and only passively guarding against harmless animals. Nevertheless, shrikes hesitate to attack the Eurasian magpie (Pica pica), which specializes in plundering passerine nests. Our previous studies have suggested that this behaviour may be the result of an alternative defence strategy, relying on nest crypsis. To test this hypothesis, at the shrike nests, we presented a magpie dummy associated with playbacks drawing the predators' attention to the presence of the nest. We predicted that the presentation of a magpie dummy associated with shrike alarm calls moves the parents to action, causing them to chase the magpie away from the nest. We showed that the presence of a magpie dummy associated with shrike alarm calls elicits a significantly more active response in shrike parents compared to a magpie dummy associated with neutral song. Parents actively moved around the dummy and produced alarm calls; nevertheless, most of the tested pairs hesitated to attack the dummy. We may conclude that the low nest defence activity of shrike parents towards magpie dummy was partly the result of an alternative strategy, which may be cancelled out by alerting the predator to the location of the nest; nevertheless, shrikes seem to be afraid of the magpie and hesitate to attack it physically.

Experimental diversionary feeding of red kites Milvus milvus reduces chick predation and enhances breeding productivity of northern lapwings Vanellus vanellus

For ground-nesting and colonial bird species, predation of eggs and chicks can exert a strong negative effect on population growth and recovery. For declining populations of waders breeding on lowland wet grassland predation management tools are available to reduce the impacts of mammalian predators (e.g. lethal control, exclusion) but potential solutions are limited when raptors, which are often themselves protected by law and not easily excluded, are responsible for predation. Diversionary feeding (DF), where predators are provided with alternative food to replace the target prey species in their diet, has been tested successfully by providing food close to nesting raptor pairs to target specific individuals. Where many individuals are involved in predation at a single prey colony, or where locating or accessing nests is difficult, provisioning DF close to the focal prey colony may be a more practical solution. Here, we test the efficacy of providing DF in this way to reduce predation by red kites, a reintroduced and increasingly abundant protected raptor in the UK, on the chicks of northern lapwing, an internationally declining wader species. We conducted a five-year field experiment, comparing kite predation rates and breeding productivity of lapwings in years before, during and after DF. Rates of kite predation on lapwing chicks were substantially and significantly reduced in DF years due to the successful elimination of a May-June peak in kite predation by DF which coincided with the kite chick provisioning and lapwing chick rearing periods. These annual reductions in kite predatory strike rates were concurrent with marked increases in overall annual lapwing productivity, which more than doubled on average in DF years and were on a scale sufficient to facilitate lapwing population recovery. DF attracted other potential predators of lapwing eggs and chicks, and more kites were attracted to feeding stations than were initially targeted by DF, but neither had any measurable impact on lapwing breeding success during DF years or after its cessation. With increasing populations of many raptor species, predator-prey conservation conflicts are expected to increase. DF proved to be a highly effective predation management tool for a high-density wader colony on lowland wet grassland where intensive kite predation limited breeding success. Although evaluation of the effects of using DF continuously over several years is needed, targeting multiple predator individuals close to the focal prey of conservation concern may be an important predation management tool where accessing individual raptors at nest sites is impractical.

Predation by white-fronted capuchin monkeys, Cebus albifrons on eggs of three species of freshwater turtles in Brazilian Amazonia: solitary nests are also depredated

ABSTRACT Although freshwater turtles are well-known for group nesting, most species are solitary nesters, often deploying nest concealment to reduce egg predation risk. Records of predation on such taxa are much less common than on synchronously nesting species, most likely due to the scattered distribution and inconspicuousness of such nests. Here, we report depredation in Jaú National Park, Amazonas, Brazil, by a diurnal generalist Neotropical primate (White-fronted capuchin, Cebus albifrons), on nests of three freshwater turtle species (Kinosternon scorpioides, Peltocephalus dumerilianus, both obligate solitary nesters, and Podocnemis erythrocephala, which does so facultatively). The species involved were identified by distinct characteristics of the eggs and nests (turtles), and impressions of the hands and feet (primates). While the current report shows that nests are subject to predation by generalist species such as white-fronted capuchins, the extent to which this impacts local turtle populations remains unclear. Further studies should address whether or not this is a general phenomenon or the result of a local foraging strategy by the primate concerned. Field-based, preferably long-term, studies are recommended to answer such questions.

All day-long: Sticklebacks effectively forage on whitefish eggs during all light conditions.

The three-spined stickleback Gasterosteus aculeatus invaded Lake Contance in the 1940s and expanded in large numbers from an exclusively shoreline habitat into the pelagic zone in 2012. Stickleback abundance is very high in the pelagic zone in winter near the spawning time of pelagic whitefish Coregonus wartmanni, and it is hypothesized that this is triggered by the opportunity to consume whitefish eggs. Field sampling has qualitatively confirmed predation of whitefish eggs by stickleback, but quantification has proven difficult due to stormy conditions that limit sampling. One fundamental unknown is if freshwater stickleback, known as visual feeders, can successfully find and eat whitefish eggs during twilight and night when whitefish spawn. It is also unknown how long eggs can be identified in stomachs following ingestion, which could limit efforts to quantify egg predation through stomach content analysis. To answer these questions, 144 individuals were given the opportunity to feed on whitefish roe under daylight, twilight, and darkness in controlled conditions. The results showed that stickleback can ingest as many as 100 whitefish eggs under any light conditions, and some individuals even consumed maximum numbers in complete darkness. Furthermore, eggs could be unambiguously identified in the stomach 24 hours after consumption. Whitefish eggs have 28% more energy content than the main diet of sticklebacks (zooplankton) based on bomb-calorimetric measurements, underlining the potential benefits of consuming eggs. Based on experimental results and estimates of stickleback abundance and total egg production, stickleback could potentially consume substantial proportions of the total eggs produced even if relatively few sticklebacks consume eggs. Given the evidence that stickleback can feed on eggs during nighttime spawning and may thereby hamper recruitment, future studies aimed at quantifying actual egg predation and resulting effects on the whitefish population are urgently needed.

Macroecology of North European Wet Grassland Landscapes: Habitat Quality, Waders, Avian Predators and Nest Predation

Wet grassland degradation is a global issue that involves both altered land cover patterns and ecological processes, which affect the distribution and abundance of species. The sharp decline in European wader bird (Charadrii) populations is a good example. The aim of this study is to test the hypothesis that the anthropogenic developmental stage of wet grassland habitats and landscapes drives avian nest predator abundance, and thus the predation pressure on nests, which is a major cause of wader bird declines. Using a macroecological approach we selected six wet grassland landscapes representing a gradient in both grassland habitat development and breeding wader population status in four European countries (Belarus, Iceland, Lithuania and Sweden). We (1) mapped wader and avian predator assemblages in multiple wet grassland patches in each landscape, (2) used artificial nests to estimate the relative rate of egg predation, and (3) analyzed relationships between nest predation pressure, corvid nest predators versus raptors, nest loss and the stage of wet grassland habitat and landscape development. We found (1) inverse relationships between the abundance of corvids and waders, as well as between wet grassland developmental stage and waders, and (2) a positive correlation between the probability of nest loss and the density of corvid birds. In conclusion, we found a clear macroecological pattern linking habitat quality, wader populations, nest predators and nest predation. These linkages stress the importance of including nest predation as a factor limiting wader bird populations, and that corvid control or management may be useful management tools.