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In the North Atlantic, the waters surrounding the Cape Verde Islands are a "potential hot spot" for cookiecutter shark Isistius spp. interactions with cetaceans. These occurrences were recently identified by the improved efforts of researchers to document cetacean strandings in the Cape Verde archipelago, as well as by the photo identification efforts of live whales and dolphins. The documentation of individual and mass stranding events confirmed that cookiecutter shark interactions with cetaceans in Cape Verde seas are remarkably common.
The African shieldbug genus Afrius Stål, 1870 is revised. Cantheconidea migratoria Distant, 1913 and A. williamsi Miller, 1952 are proposed as junior synonyms of A. (Subafrius) flavirostrum (Signoret, 1861) whereas Canthecona marmorata Dallas, 1851, Canthecona annulipes Dallas, 1851 and A. rubromarginatus Bergroth, 1903 are proposed as junior synonyms of A. (Afrius) purpureus (Westwood, 1837) based on the general morphology and genitalia of the species. The three valid species, viz. A. (Subafrius) flavirostrum, A. (Afrius) kolleri Schouteden, 1911 and A. (Afrius) purpureus, are redescribed with details of male and female genitalia morphology, and a lectotype is designated for A. (Afrius) kolleri. A key to identify the species as well as an update of the geographical distribution for each species are provided, including new records for A. (Afrius) purpureus.
The interactions between the lacewing Ceraeochrysa claveri (Navás) (Neuroptera: Chrysopidae) larva and the coconut mealybug Nipaecoccus nipae (Maskell) (Hemiptera: Pseudococcidae) were recorded. The third-instar lacewing larva constructed a dorsal packet using mealybug wax from both male pupal cases and the bodies of adult females. Surprisingly, live nymphs were also frequently placed into the dorsal packet. Prey mealybugs were discarded and not incorporated into the packet after consumption. When disturbed, adult female mealybugs reflex bled from their dorsal ostioles, contacting the mouthparts of the lacewing. The lacewing quickly retreated to clean the mouthparts on the substrate, providing further evidence that ostiolar fluids act as a defense mechanism for mealybugs. Despite repeatedly contacting the ostiolar fluid, the lacewing pupated and eclosed successfully. Macro video footage of dorsal packet construction and ostiolar reflex bleeding is included. This is the first report of C. claveri preying on N. nipae, the first evidence of C. claveri using mealybug wax to construct the dorsal packet, and the first account of reflex bleeding via the dorsal ostioles to deter predators in N. nipae.
ZooBank registration. urn:lsid:zoobank.org:pub:CCEE7B47-B6E9-4D36-8860-A7F4DE5E717B
The success of invading species can be restricted by interspecific interactions such as competition and predation (i.e. biotic resistance) from resident species, which may be natives or previous invaders. Whilst there are myriad examples of resident species preying on invaders, simply showing that such an interaction exists does not demonstrate that predation limits invader establishment, abundance or spread. Support for this conclusion requires evidence of negative associations between invaders and resident predators in the field and, further, that the predator-prey interaction is likely to strongly regulate or potentially de-stabilise the introduced prey population. Moreover, it must be considered that different resident predator species may have different abilities to restrict invaders. In this study, we show from analysis of field data that two European predatory freshwater amphipods, Gammarus pulex and G. duebeni celticus, have strong negative field associations with their prey, the invasive North American amphipod Crangonyx pseudogracilis. This negative field association is significantly stronger with G. pulex, a previous and now resident invader in the study sites, than with the native G. d. celticus. These field patterns were consistent with our experimental findings that both resident predators display potentially population de-stabilising Type II functional responses towards the invasive prey, with a significantly greater magnitude of response exhibited by G. pulex than by G. d. celticus. Further, these Type II functional responses were consistent across homo- and heterogeneous environments, contrary to the expectation that heterogeneity facilitates more stabilising Type III functional responses through the provision of prey refugia. Our experimental approach confirms correlative field surveys and thus supports the hypothesis that resident predatory invertebrates are differentially limiting the distribution and abundance of an introduced invertebrate. We discuss how the comparative functional response approach not only enhances understanding of the success or failure of invasions in the face of various resident predators, but potentially also allows prediction of population- and communitylevel outcomes of species introductions.
Auch in den arktischen Brutgebieten sind Wildgänse und ihre Brut durch Fressfeinde wie den Eisfuchs (Alopex lagopus) oder die Eismöwe (Larus hyperboreus) gefährdet. In diesem Bericht wird am Beispiel von Weißwangengänsen (Branta leucopsis) das Verhalten der Vermeidung von Prädation auf Svalbard mit dem der auf Kolguyev brütenden Artgenossen untersucht. Die Unterschiede und Gemeinsamkeiten werden diskutiert.
Invasive alien American bullfrog populations are commonly identified as a pernicious influence on the survival of native species due to their adaptability, proliferation and consequent ecological impacts through competition and predation. However, it has been difficult to determine conclusively their destructive influence due to the fragmentary and geographically dispersed nature of the historical database. An expanding meta-population of invasive American bullfrogs, Rana catesbeiana (= Lithobates catesbeianus), became established on southern Vancouver Island, British Columbia, Canada in the mid- to late 1980s. An on-going bullfrog control program begun in 2006 offered a unique opportunity to examine the stomach contents removed from 5,075 adult and juvenile bullfrogs collected from 60 sites throughout the active season (April to October). Of 15 classes of organisms identified in the diet, insects were numerically dominant, particularly social wasps and odonates (damselflies and dragonflies). Seasonality and site-specific habitat characteristics influenced prey occurrence and abundance. Native vertebrates in the diet included fish, frogs, salamanders, snakes, lizards, turtles, birds, and mammals, including some of conservation concern. Certain predators of bullfrog tadpoles and juveniles are commonly preyed upon by adult bullfrogs, thereby suppressing their effectiveness as biological checks to bullfrog population growth. Prey species with antipredator defences, such as wasps and sticklebacks, were sometimes eaten in abundance. Many prey species have some type of anti-predator defence, such as wasp stingers or stickleback spines, but there was no indication of conditioned avoidance to any of these. Results from this study reinforce the conclusion that, as an invasive alien, the American bullfrog is an opportunistic and seemingly unspecialized predator that has a uniquely large and complex ecological footprint both above and below the water surface.
Established populations of non-natives may collapse without a clear causal mechanism. Hypothetically, fluctuations in habitat structural complexity may influence dynamics of invaders and the biotic resistance offered by predators. Herein I report observations of the collapse of a reproducing population of the nonnative African jewelfish (Hemichromis letourneuxi) in a Florida lake concurrent with an unusual low-water period. I test the hypothesis that predation may have played a key role in the collapse using a combination of field surveys of habitat and fish abundance and predator-prey experiments. Habitat complexity was high before and after the low water period but virtually nonexistent during low water. The abundance of African jewelfish and native juvenile bluegill (Lepomis macrochirus) and eastern mosquitofish (Gambusia holbrooki) declined concurrently with decreasing complexity but the native species rebounded when lake levels increased. Large-bodied natives such as largemouth bass (Micropterus salmoides) and adult bluegill showed no pattern of fluctuation related to habitat complexity. African jewelfish survival was 1.6 times greater at high versus low complexity and over 7 times higher versus no complexity in the presence of largemouth bass. Conversely, eastern mosquitofish, a species that exerts strong effects on small-bodied fishes in structurally complex habitats had no effect on African jewelfish survival. Predation effects on susceptible non-natives should be considered as a potential control action. Population collapse is understudied but may provide insights into long-term dynamics of invaders and information useful for management of problematic species.
The ability of wild animals to navigate and survive in complex and dynamic environments depends on their ability to store relevant information and place it in a spatial context. Despite the centrality of spatial memory, and given our increasing ability to observe animal movements in the wild, it is perhaps surprising how difficult it is to demonstrate spatial memory empirically. We present a cognitive analysis of movements of several wolves (Canis lupus) in Finland during a summer period of intensive hunting and den-centered pup-rearing. We tracked several wolves in the field by visiting nearly all GPS locations outside the den, allowing us to identify the species, location and timing of nearly all prey killed. We then developed a model that assigns a spatially explicit value based on memory of predation success and territorial marking. The framework allows for estimation of multiple cognitive parameters, including temporal and spatial scales of memory. For most wolves, fitted memory-based models outperformed null models by 20 to 50% at predicting locations where wolves chose to forage. However, there was a high amount of individual variability among wolves in strength and even direction of responses to experiences. Some wolves tended to return to locations with recent predation success—following a strategy of foraging site fidelity—while others appeared to prefer a site switching strategy. These differences are possibly explained by variability in pack sizes, numbers of pups, and features of the territories. Our analysis points toward concrete strategies for incorporating spatial memory in the study of animal movements while providing nuanced insights into the behavioral strategies of individual predators.
In the published article, there was an error regarding the affiliation for Diana Abondano Almeida. As well as having affiliation 2, they should also have Department of Wildlife-/Zoo-Animal-Biology and Systematics, Faculty of Biological Sciences, Goethe Universität, Frankfurt, Germany.
The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated.