Prey Choice Research Articles

Detection of prey odours underpins dietary specialization in a Neotropical top-predator: How army ants find their ant prey.

Deciphering the mechanisms that underpin dietary specialization and niche partitioning is crucial to understanding the maintenance of biodiversity. New world army ants live in species-rich assemblages throughout the Neotropics and are voracious predators of other arthropods. They are therefore an important and potentially informative group for addressing how diverse predator assemblages partition available prey resources. New World army ants are largely specialist predators of other ants, with each species specializing on different ant genera. However, the mechanisms of prey choice are unknown. In this study, we addressed whether the army ant Eciton hamatum: (a) can detect potential prey odours, (b) can distinguish between odours of prey and non-prey and (c) can differentiate between different types of odours associated with its prey. Using field experiments, we tested the response of army ants to the following four odour treatments: alarm odours, dead ants, live ants and nest material. Each treatment had a unique combination of odour sources and included some movement in two of the treatments (alarm and live ants). Odour treatments were tested for both prey and non-prey ants. These data were used to determine the degree to which E. hamatum are using specific prey stimuli to detect potential prey and direct their foraging. Army ants responded strongly to odours derived from prey ants, which triggered both increased localized recruitment and slowed advancement of the raid as they targeted the odour source. Odours from non-prey ants were largely ignored. Additionally, the army ants had the strongest response to the nest material of their preferred prey, with progressively weaker responses across the live ant, dead ant and alarm odours treatments respectively. This study reveals that the detection of prey odours, and especially the most persistent odours related to the prey's nest, provides a mechanism for dietary specialization in army ants. If ubiquitous across the Neotropical army ants, then this olfaction-based ecological specialization may facilitate patterns of resource partitioning and coexistence in these diverse predator communities.

Revisiting more or less: influence of numerosity and size on potential prey choice in the domestic cat.

Quantity discrimination is of adaptive relevance in a wide range of contexts and across a wide range of species. Trained domestic cats can discriminate between different numbers of dots, and we have shown that they also spontaneously choose between different numbers and sizes of food balls. In the present study we performed two experiments with 24 adult cats to investigate spontaneous quantity discrimination in the more naturalistic context of potential predation. In Experiment 1 we presented each cat with the simultaneous choice between a different number of live prey (1 white mouse vs. 3 white mice), and in Experiment 2 with the simultaneous choice between live prey of different size (1 white mouse vs. 1 white rat). We repeated each experiment six times across 6 weeks, testing half the cats first in Experiment 1 and then in Experiment 2, and the other half in the reverse order. In Experiment 1 the cats more often chose the larger number of small prey (3 mice), and in Experiment 2, more often the small size prey (a mouse). They also showed repeatable individual differences in the choices which they made and in the performance of associated predation-like behaviours. We conclude that domestic cats spontaneously discriminate between the number and size of potential prey in a way that can be interpreted as adaptive for a lone-hunting, obligate carnivore, and show complex levels of risk-reward analysis.

Capitalizing on an ecological process to aid coral reef ecosystem restoration: Can gastropod trophodynamics enhance coral survival?

Coral reefs in the Florida Keys have degraded in recent decades, prompting efforts to re-establish populations of staghorn coral, Acropora cervicornis, to restore structure and ecological function. However, predation on these corals by the corallivorous gastropod, Coralliophila galea, has been a substantial and chronic impediment to restoration efforts. Therefore, we conducted a series of manipulative laboratory experiments and a 2-week, in situ proof-of-concept trial to determine whether Thais deltoidea, a carnivorous gastropod that co-occurs with C. galea, can control C. galea corallivory and thus improve A. cervicornis survival. Our laboratory results showed that T. deltoidea preys upon C. galea, although it is not a preferred prey choice. Nevertheless, treatments with T. deltoidea had significantly higher percentages of live coral tissue than when T. deltoidea was absent. This occurred not only because T. deltoidea consumed C. galea, but also because the presence of T. deltoidea elicited an escape response in C. galea, significantly reducing the amount of time C. galea spent feeding on A. cervicornis colonies. This trophic relationship was also seen in our in situ proof-of-concept trial. We observed significantly fewer C. galea on A. cervicornis when T. deltoidea was present which led to a higher, if not statistically significant, percentage of live tissue on our A. cervicornis outplants. Ecological processes need to be incorporated into coral reef ecosystem restoration to achieve positive outcomes. Integrating T. deltoidea into coral restoration efforts may improve success by mitigating C. galea corallivory through the non-consumptive, risk-adverse, escape response that T. deltoidea provokes, initiating a trophic cascade that improves the long-term survival of outplanted corals. Further research is needed to determine the long-term efficacy of this approach, but the addition of gastropod trophodynamics to coral reef ecosystem restoration may prove useful.

Dietary study using set-nets produces bias in prey choice of fish: A case of three coastal fishes inhabiting southern Korean waters

Prey selection by marine fishes is highly dependent on whether available food resources are abundant or deficient in their feeding grounds. The influence of fishing method on prey choice was analyzed via stomach content analyses of three coastal fishes: Pennahia argentata, Sillago japonica, and Thryssa kammalensis. Fish samples were collected from northern Jinju Bay, Korea, using two types of fishing gear that covered two different fishing layers in the water column: beam-trawl (bottom layer) and set-net (surface layer). When caught via beam-trawl, all three target species were function as bottom-feeding carnivores that consumed mainly benthic crustaceans and other invertebrates. In contrast, when caught via set-net, teleosts were the most abundant prey items in the diets of the three species. Significant differences in the diet composition between beam-trawl and set-net samples were revealed using permutational multivariate analysis of variance. Although seasonal changes in diet composition were also evident, the influence of season was weaker than that of fishing gear. Consequently, in this study, stomach content analysis demonstrated that set-net made a strong effect on prey selection by the co-occurring P. argentata, S. japonica, and T. kammalensis in southern Korean waters.

Linking hunting weaponry to attack strategies in sailfish and striped marlin.

Linking morphological differences in foraging adaptations to prey choice and feeding strategies has provided major evolutionary insights across taxa. Here, we combine behavioural and morphological approaches to explore and compare the role of the rostrum (bill) and micro-teeth in the feeding behaviour of sailfish (Istiophorus platypterus) and striped marlin (Kajikia audax) when attacking schooling sardine prey. Behavioural results from high-speed videos showed that sailfish and striped marlin both regularly made rostrum contact with prey but displayed distinct strategies. Marlin used high-speed dashes, breaking schools apart, often contacting prey incidentally or tapping at isolated prey with their rostra; while sailfish used their rostra more frequently and tended to use a slower, less disruptive approach with more horizontal rostral slashes on cohesive prey schools. Capture success per attack was similar between species, but striped marlin had higher capture rates per minute. The rostra of both species are covered with micro-teeth, and micro-CT imaging showed that species did not differ in average micro-tooth length, but sailfish had a higher density of micro-teeth on the dorsal and ventral sides of their rostra and a higher amount of micro-teeth regrowth, suggesting a greater amount of rostrum use is associated with more investment in micro-teeth. Our analysis shows that the rostra of billfish are used in distinct ways and we discuss our results in the broader context of relationships between morphological and behavioural feeding adaptations across species.

Black gill increases the susceptibility of white shrimp, Penaeus setiferus (Linnaeus, 1767), to common estuarine predators

Parasites can kill hosts directly, but also indirectly, by enhancing susceptibility to environmental factors and biotic interactions. In the United States South Atlantic Bight region of the northwest Atlantic Ocean, white shrimp (Penaeus setiferus) support a substantial commercial fishery and are also valuable prey for many marine and estuarine species. Since the late 1990s, a condition known as black gill has been observed in penaeid shrimp in the South Atlantic Bight. In this region, black gill has been linked to an apostome ciliate that elicits an innate immune response in shrimp, manifested through the melanization of gill tissues, which impedes respiratory functions and hemolymph ion regulation. The objective of this study was to determine if black gill subjects shrimp to higher rates of predation by red drum (Sciaenops ocellatus), spotted seatrout (Cynoscion nebulosus), and blue crab (Callinectes sapidus). A series of simultaneous prey choice mesocosm experiments was conducted, during which single-species predators were able to consume shrimp that were both symptomatic and asymptomatic of black gill over a four-hour period. Predator species were 1.4 to 3.0 times more likely to consume symptomatic shrimp than asymptomatic shrimp. The hinderance of shrimp physiology and escape responses due to gill melanization likely increases the vulnerability of shrimp to predation. This study emphasizes that mortality from parasitic infections is not always direct and that black gill may have a significant impact on penaeid shrimp through secondary, or indirect, mortality.

Primates are an important food resource for leopards (Panthera pardus) in Mahale, Tanzania

AbstractLeopard diets in the Kasoje area of the Mahale Mountains National Park, Tanzania, were analysed by inspecting prey remains in 256 scats. This area is unique as leopard density is high despite a relatively low density of medium‐sized ungulates, regarded as the most preferred prey of leopards. At least eleven prey mammal species were confirmed in the scats. Small prey mammals up to 10 kg comprised 91.4% of the relative biomass consumed; the mean prey biomass in each scat was 7.6 kg. Blue duiker (31.2%) was the most dominant prey species, followed by the red colobus (29.2%), semi‐terrestrial Cercopithecinae (the vervet monkey and yellow baboon combined) (10.5%) and the red‐tailed monkey (9.9%). At the order level, the most consumed prey taxon was Primates (53.8%), followed by Cetartiodactyla (39.6%) and Rodentia (5.8%). Among primates, the blue monkey was the most preferred prey species, followed by the red colobus and semi‐terrestrial Cercopithecinae. High consumption of primates is a unique characteristic of the leopards in Mahale. This trend exemplifies the flexibility of leopards in their choices of prey, and such flexibility may be one of the underlying reasons for leopards exhibiting the broadest global distribution among all wild felid species.

Mesolithic deer hunting – Prey choice of red deer (Cervus elaphus) based on age and sex distributions

The Mesolithic hunting on red deer (Cervus elaphus) has been examined by analysis of prey choice through the age and sex distributions based on dentition and morphometry of zooarchaeological remains from five Mesolithic settlements in Sweden dating to 9000–6000 cal BP. The results indicate a general selection of individuals aged 2–5 years at most sites, while the sex distribution was skewed toward either stags or hinds. The hunting was directed towards animals that provided high immediate and short-term returns of meat. Few observations point to hunting patterns that would have been associated to conservational perspectives of the red deer populations. A comparison indicates that local and site-specific differences in hunting practise can be discerned which probably was related to local conditions linked to environment, function of sites and hunting traditions, but no distinct correlation of hunting pattern to chronology or different regions. The study shows the potential to evaluate kill-off patterns in relation to optimal foraging perspectives restricted to one prey species.

Interactions Between the Nematode Heterorhabditis amazonensis JPM4 and the Predator Macrolophus basicornis: Two Natural Enemies of Tuta absoluta Native to South America.

Entomopathogenic nematodes (EPNs) and predatory mirids are among the most effective natural enemies for the control of Tuta absoluta, a key pest of tomato worldwide. In the case of South America, the native EPN Heterorhabditis amazonensis and the predator Macrolophus basicornis (Stal) coexist in tomato. The intraguild interactions of two ENPs, H. amazonensis JPM4 and the widely used Steinernema carpocapsae, with the predator M. basicornis, were studied in laboratory setups with the objective of evaluating the potential interactions between them. We hypothesized that the two natural enemies do not interact negatively. The first nymphal stage of the predator was not affected when exposed to tomato leaves directly sprayed with both EPNs, which we attributed to the small size of its stylet. Individuals treated with H. amazonensis JPM4 had low mortality rates in all developmental stages with a maximum of 1.3%. Mortality was higher when the predator was exposed to S. carpocapsae (28% for adults) and correlated positively with increasing developmental stages. In prey choice tests between larvae infected with H. amazonensis and uninfected larvae, M. basicornis fed indistinctively showing no clear preference. When presented with choice larvae infected with S. carpocapsae, the consumption of healthy larvae was higher. In a no-choice prey acceptance experiment, M. basicornis preyed on both healthy and infected larvae with no difference in larvae consumed. Predators that had fed from infected larvae did not exhibit signs of nematode infection and survived. Our results indicate that the South American native H. amazonensis JPM4 and M. basicornis do not show a negative interaction and are promising candidates for combined use in T. absoluta biological control.

Alternative prey impedes the efficacy of a natural enemy of mosquitoes

Adaptive foraging behaviour in the presence of multiple prey types may mediate stability to predator-prey relationships. For biological control agents, the presence of alternative prey may thus reduce ecological impacts towards target organisms, presenting a key challenge to the derivation of agent efficacies. Quantifications of non-target effects are especially important for generalist biocontrol agents in their regulation of pests, vectors and invasive species. We examined the predatory impact of the notonectid Anisops debilis towards larvae of the vector mosquito complex Culex pipiens in the presence of varying densities of alternative daphniid prey. Experimentally, we quantified functional responses of A. debilis towards target mosquito prey under different background daphniid compositions, and also tested for prey switching propensities by the notonectid predator. Increasing background densities of daphniids significantly reduced the predatory impact of notonectids on mosquitoes, characterised by reductions in attack rates, lengthening of handling times and lessening of maximum feeding rates. Furthermore, notonectids displayed a significant selective preference in favour of daphniid prey over mosquitoes, irrespective of prey proportions in aquatic environments. Accordingly, notonectids did not display a prey switching pattern. We thus demonstrate that the presence of alternative prey can dampen predatory impacts of notonectids towards mosquitoes, as compared to more simplistic pairwise systems with singular prey choice. Accordingly, the effects of stabilising mechanisms, such as adaptive foraging, should be further integrated in biocontrol agent assessments.

Mesocarnivores affect hispid cotton rat (Sigmodon hispidus) body mass

Predator communities are changing worldwide: large carnivores are declining while mesocarnivores (medium-sized mammalian predators) are increasing in number and ecological influence. Predator choice of prey is not random and different predators select prey with different characteristics. Changes in predator communities can change predation patterns experienced by prey. Little is known about how mesocarnivore communities influence prey morphology. We used 14 years of mark-recapture data to investigate how mesocarnivore exclusion affected body mass of hispid cotton rats (Sigmodon hispidus). Finding adult male cotton rats were 9% heavier with mesocarnivore exclusion, we developed hypotheses to explain this observation. Greater adult male body mass in exclosures resulted from: (1) a non-significant trend of increased survival of large males, (2) faster juvenile male growth during the fall and a similar non-significant trend among adult males, and (3) spatial partitioning by size among males. Taxa-specific predation rates (i.e., rates of predation by snakes, raptors, or mesocarnivores) did not differ among male body mass classes. Mesocarnivores disproportionately preyed on large females while raptors targeted small females, but female body mass was not influenced by mesocarnivore exclusion. Changes in predator communities can result in multiple small effects that collectively result in large differences in prey morphology.

Evaluating population impacts of predation by owls on storm petrels in relation to proposed island mouse eradication

AbstractWe quantify the expected demographic benefit to a seabird of conservation concern, the ashy storm‐petrel Oceanodroma homochroa, from the proposed eradication of introduced house mice Mus musculus on the South Farallon Islands, California. A key objective of the eradication is to reduce storm petrel predation by burrowing owls Athene cunicularia, which stopover on the island during their fall migration. Mouse trapping and field surveys of both owls and depredated storm petrel carcasses conducted during 2000–2012 reveal a strongly seasonal, inter‐related pattern among the three species: When owls arrive during the fall, mice are super‐abundant and the overwhelming choice of prey for those owls that remain. In the winter, the mouse population crashes just as storm petrels begin to arrive in large numbers; owls that remain on the island switch to preying upon storm petrels until May, when they depart to breed. Capture–recapture analyses of storm petrels showed (1) annual adult survival was inversely related to owl abundance, especially during January–April, and (2) storm petrels demonstrated a declining trend in abundance 2006–2012. The latter was associated with low rates of adult survival, high abundance of overwintering burrowing owls, and high incidence of depredated storm petrels. To evaluate projected impacts to storm petrels of a change in owl predation, we developed a Leslie matrix model, incorporating environmental stochasticity. We modeled future storm petrel population trajectories, allowing for different levels of owl‐mediated predation. Our results suggest that a reduction in owl abundance, a projected consequence of the elimination of mice, has the potential to substantially reduce overall storm petrel mortality, thereby reducing storm petrel declines and increasing the likelihood of stable trends in the future. While long‐term benefits to storm petrels of mouse eradication are apparent, the risk of increased predation due to prey‐switching by owls also needs to be addressed. This study highlights uncertainty of outcomes, which must be considered in evaluating management impacts. This study demonstrates the value of concurrent, continuous, long‐term datasets in providing a quantitative basis for management to aid the conservation of species of concern.

Foraging patterns and diet composition of breeding Pied avocets (Recurvirostra avosetta) in the German Wadden Sea

Pied avocets (Recurvirostra avosetta) breeding in the Wadden Sea typically forage in shallow water, using their characteristic upward-curved bill to feed on macrozooplankton in the water column and prey items in the uppermost centimetre of the sediment. Former studies on prey choice based on droppings and visual observations of feeding behaviour suggested that ragworms were the main prey items of avocets. The present study combined different methods to assess the foraging ecology of breeding avocets in the eastern Wadden Sea. Important foraging grounds were identified using GPS telemetry. Diet was analysed from droppings and stable isotope signatures of whole blood samples from breeding avocets at two different colonies in April–June 2014 and 2015. Analysis of droppings confirmed the former results, but stable isotope analysis suggested that marine fish comprised the highest proportion of the avocet diet by mass. Telemetry data indicated that intertidal channels close to the breeding areas were used as the main foraging grounds. Avocets performed short foraging trips (maximum distance: 0.3–5.9 km) mainly during the daytime. Logger data and diet analysis thus implied the existence of high fish densities in intertidal channels, underlining the importance of this saltmarsh habitat as foraging areas for breeding avocets.

Eat your heart out: choice and handling of novel toxic prey by predatory water rats

We investigated predator–prey interactions between cane toads (Rhinella marina) and native water rats (Hydromys chrysogaster), where toads are novel prey. We show that wild water rats preferentially targeted larger toads, and consumed specific non-toxic organs only. Rats either rapidly learned these behaviours, or adapted them from hunting native frogs.

Dietary spectrum in Himalayan wolves: comparative analysis of prey choice in conspecifics across high‐elevation rangelands of Asia

AbstractThe Himalayan wolf is one of the most basal among wolf lineages in the world today. It inhabits mostly the high elevations, northwards from the Himalayas (1500–5000 m) in the Asian region. We conducted a meta‐analysis to understand the dietary habits of Himalayan wolves and wolves of the high rangelands of Asia from seven countries (n = 22). We found 39 different prey items reported across the distribution of the Himalayan wolf from a total of 2331 scats (average of 105.95 ± 20.10 scats per study). Comparison of the relative frequency of occurrence of different prey species shows that domestic prey consumption (48.21 ± 5.61%) across the zones or continent was similar to wild prey consumption (42.94 ± 5.25%). Small wild prey species constituted approximately (24.53 ± 3.77%) of the total wolf diet. Wolves of the Asian Highlands consumed relatively more large prey (40.01 ± 5.42%) than small prey (25.19 ± 3.85%) or medium‐sized prey (23.17 ± 3.78%). Wolves consumed a larger proportion of domestic (54.92 ± 5.94%) than wild prey (36.13 ± 6.12%) in areas that had regular livestock grazing and vice versa. East, west and central Himalayan and Central Asian wolves consumed mostly large wild and domestic prey. On the contrary, wolves in the Qinghai–Tibetan Plateau, Inner Mongolia and the Karakoram consumed a relatively higher proportion of smaller‐sized prey and livestock. Overall, wolves utilized mostly domestic livestock and marmots (Ivlev’s index, 0.22–0.77). High localized utilization of Przewalski’s horse (Equus ferus przewalkskii, 0.94) was recorded, whereas Goral (N. goral) and Pika (Ochotona spp) were particularly underutilized (−0.99 and −0.92) in wolf diet. A landscape or trans‐boundary approach is advocated to restore natural large wild prey, for such a relic lineage species and reduce human‐wolf conflicts.

Effects of information load on response times in frogs and bats: mate choice vs. prey choice

Decisions tend to become more challenging as the number of available options increases and choice sets become more complex. Choosing between multiple options may require additional information processing time and effort. Here, we asked if response time increases with stimulus number and attractiveness by female frogs (Physalaemus pustulosus) and their predators, frog-eating bats (Trachops cirrhosus), when comparing the mating calls of male tungara frogs. We found that frogs’ response time is significantly longer when presented with two calls, compared with one. Bats also take longer to respond when presented with two calls but only when they were complex calls. Although the frogs and bats behave somewhat similarly in this experiment, the decisions that these animals are making are occurring in different domains (mating vs. foraging) and have different fitness consequences. Given these differences, we find it especially interesting that for both frogs and bats, we see similar temporal patterns in response times as a function of information load. SIGNIFICANCE STATEMENT: Animals are often faced with several options simultaneously. One cost of decision-making is the time involved in choosing the best option within a choice set. Here, we asked whether female frogs and frog-eating bats take longer to respond when presented multiple frog mating calls simultaneously. We also asked whether the attractiveness of those frog calls influences the time it takes frogs and bats to respond to them. We found that the time to respond was influenced by both the number and attractiveness of frog calls for both bats and frogs; however, frog response time seemed to be more greatly influenced by the number of frog calls, while bat response time seemed to be more influenced by the attractiveness of frog calls. In general, our results suggest that there may be similar mechanisms involved in decision-making for both animals.

Prey Choice by Declining Atlantic Flyway Semipalmated Sandpipers (Calidris pusilla) at a Major Wintering Area in Brazil

Eastern populations of Semipalmated Sandpipers (Calidris pusilla) have declined severely in recent decades, particularly at wintering grounds in northern South America, where about 80% of the population was lost since the 1980s. This study investigates prey choice of Semipalmated Sandpipers at two sites in major wintering grounds on the coast of Maranhao, northeast Brazil. Prey availability estimated from intertidal sediment samples was compared with bird diet reconstructed from prey remains in droppings. Birds (flocks of 80-90 birds) fed almost exclusively on the polychaete Laeonereis culveri (present in all droppings at both sites; ≥ 97% of total setae found in droppings), the most abundant invertebrate in the intertidal sediments overall, but they avoided the smallest sizes despite abundance in sediments and avoided numerous other species. Setae from two other polychaetes were found in droppings (Glycindes multidens, 53% of droppings; Hermondura tricuspis, 47% of droppings), but these represented < 2% in average of all setae in droppings. The disproportional prevalence of a single prey species in the diet of sandpipers in this study is comparable to well-studied stopover areas. High dependence on a single staple prey at different sites in the migration route can make Semipalmated Sandpipers vulnerable to changes in prey abundance, which may partly explain declines observed at the flyway level.

Modelling distribution of common scoter (Melanitta nigra) by its predominant prey, the American razor clam (Ensis leei) and hydrodynamic parameters

The non-breeding distribution of common scoter (Melanitta nigra), which occur in high densities offshore from the eastern Wadden Sea, has been well documented in recent decades, but factors influencing these patterns remain poorly known. We investigated the prey choice of 88 common scoter using stomach contents of beached birds collected over a period of 12 years. We then used benthos data and hydrodynamic parameters to model the June–September distribution patterns during the flightless period of common scoter based on transect count data off the north-eastern German Wadden Sea.Benthic fauna biomass in areas used by common scoter was higher than in areas where the species was absent. American razor clam (Ensis leei) invaded the Wadden Sea during the end of the 1970s and was the most common prey, both in benthos samples from below feeding common scoter and in stomach samples. The relatively high flesh to shell ratio of the American razor clam makes it the most attractive available prey item for common scoter.The abundance of American razor clams explained the distribution of scoter to a high degree, although the best model fit included negative effects of water depth and positive effects of bed shear stress intensity on scoter abundance. Our data show that the neobiotic American razor clams have become an important part of the diet of these sea ducks, whereas the cut trough shell (Spisula subtruncata) was of substantially lesser importance than expected from historical data. Our study shows the ability of a top avian predator to respond to novel developments in bivalve prey availability over periods of a few decades.

Early Upper Paleolithic subsistence in the Levant: Zooarchaeology of the Ahmarian–Aurignacian sequence at Manot Cave, Israel

The Early Upper Paleolithic period in the Levant is essential in the studies of the establishment of modern human communities outside Africa, and corresponding archaeological evidence may be used to shed light on human ecology, economy and demography. Specifically, cultural differences between two Early Upper Paleolithic entities, the Early Ahmarian and the Levantine Aurignacian, raise the question of differing adaptations. In this article we use archaeofaunal remains from the Early Upper Paleolithic sequence at Manot Cave (Western Galilee, Israel), to track human hunting patterns, carcass transport and processing within the Early Ahmarian (46–42 ka) and Levantine Aurignacian (38–34 ka) phases. We test two hypotheses: 1) the Ahmarian and Aurignacian represent adaptations to different environments; and 2) the two entities differ in mobility patterns and site use.Our multivariate taphonomic analysis showed subtle differences in depositional processes between the two phases and demonstrated a primarily anthropogenic complex. In both phases, human subsistence was based on two ungulate species, mountain gazelle (Gazella gazella) and Mesopotamian fallow deer (Dama mesopotamica), with some contribution from birds, tortoises and small mammals. Among the gazelles, it appears that female herds were targeted, and that hunting took place close to the cave. The results of the research show great similarity in environmental exploitation between the Ahmarian and Aurignacian phases concerning prey spectrum and choice, carcass transport and processing. These patterns occupy a middle position between the Middle Paleolithic and the late Epipaleolithic of the region. Despite this, there are also several significant differences between the phases such as increased exploitation of small game (especially birds) and faster accumulation and higher densities of material in the Aurignacian. This may indicate greater occupation intensity during the Aurignacian compared to the Ahmarian, and thus could explain the outstanding character of this entity in the Levant.

Reproductive success in the European shag is linked to annual variation in diet and foraging trip metrics

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 619:137-147 (2019) - DOI: https://doi.org/10.3354/meps12949 Reproductive success in the European shag is linked to annual variation in diet and foraging trip metrics Svein-Håkon Lorentsen1,*, Jenny Mattisson1, Signe Christensen-Dalsgaard1,2 1Norwegian Institute for Nature Research, 7485 Trondheim, Norway 2Department of Biology, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway *Corresponding author: shl@nina.no ABSTRACT: Seabird populations have declined worldwide, and several of the potential threats are of anthropogenic origin. To understand how changes in seabird populations relate to environmental conditions it is important to know the functional relationships between prey availability and foraging behaviour, prey choice and breeding performance over several years. This was studied by linking breeding success of European shag Phalacrocorax aristotelis to variation in diet composition, and investigating the underlaying mechanism driving this variation, primarily based on behavioural costs associated with foraging, such as foraging range and diving effort. We obtained demographic data and foraging trip metrics (using GPS-loggers and time-depth recorders) from a shag colony at Sklinna, Central Norway, during the 2011-2016 breeding seasons. Breeding population size was closely and positively correlated with breeding success, which in turn was positively correlated with the proportion of saithe Pollachius virens in the diet. When the dietary proportion of uncommon prey species increased, breeding success decreased. Breeding success was negatively influenced by increasing distance travelled and accumulated dive depths on an annual basis. Summed dive depths were greatest when prey species other than saithe dominated the diet. We found that in years with low availability of saithe fewer shags bred, and those that did had lower breeding success. This indicates that in years with poor feeding conditions, there might not be sufficient resources in the foraging area to support the whole breeding population of shags. KEY WORDS: Phalacrocorax aristotelis · Seabird diet · Saithe · Pollachius virens · Foraging range · Trip length · Dive depth Full text in pdf format Supplementary material PreviousNextCite this article as: Lorentsen SH, Mattisson J, Christensen-Dalsgaard S (2019) Reproductive success in the European shag is linked to annual variation in diet and foraging trip metrics. Mar Ecol Prog Ser 619:137-147. https://doi.org/10.3354/meps12949 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 619. Online publication date: June 04, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.