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[EN] Exploratory behaviour and foraging strategies in Mediterranean blue tits. Animal behaviour is potentially a mechanism of individual diet specialization. To explore this possibility we assessed exploratory behaviour (EB) and foraging data for a population of blue tits Cyanistes caeruleus. Our results suggest that: 1) foraging differs between sexes; 2) the prey type selected by females depends on the provisioning rates of their mate, and adjustment of this prey-choice differs between EB phenotypes; and 3) foraging behaviour in males shows a trend towards linkage to their EB phenotype, with faster-exploring males obtaining marginally larger caterpillars but provisioning less frequently than slower-exploring males. Lastly, environmental variables contributed substantially to the diet composition of offspring. For this reason, we cannot suggest that EB dominates, but it may contribute to a diet specialization process in our study population., [ES] Comportamiento exploratorio y estrategias de búsqueda de alimento en herrerillos Mediterráneos. El comportamiento animal tiene la capacidad de ser un mecanismo de especialización individual de la dieta. Para comprobarlo, se estudió el comportamiento exploratorio (EB por su sigla en inglés) y se obtuvieron datos sobre búsqueda de alimento en una población de herrerillo común, Cyanistes caeruleus. Los resultados muestran que 1) existen diferencias en la búsqueda de alimento entre sexos; 2) el tipo de presa elegido por las hembras depende de la frecuencia de aprovisionamiento de su pareja y este ajuste de la elección de la presa difiere entre los fenotipos de EB; y 3) existe una tendencia que relaciona el comportamiento de búsqueda de alimentos de los machos con su EB, por la que los machos con un comportamiento exploratorio más rápido obtienen orugas marginalmente más grandes, pero alimentan a sus pollos menos veces que los exploradores más lentos. Por último, las variables ambientales contribuyeron sustancialmente a la composición de la dieta de los pollos de herrerillo. Por ello, no podemos sugerir que el EB sea el principal factor determinante de los procesos de especialización de la dieta en la población estudiada, pero sí que puede contribuir a dichos procesos., The projects CGL2016–79568–C3–1–P and PID2021–12217NB–I00 (Ministerio de Ciencia e Innovación) contributed to funding this study. Additionally, ACV was financially supported by a pre–doctoral FPI grant (BES–2017–079803; Ministerio de Ciencia e Innovación–European Social Fund). We thank three anonymous reviewers that contributed to improving this paper.

Between the years 2008 and 2013, six annual research expeditions were carried out at Dyer Island (Gansbaai, South Africa) to study the surface behaviour of white sharks in the presence of two passive prey: tuna bait and a seal-shaped decoy. Sightings were performed from a commercial cage-diving boat over 247 h, 250 different white sharks, with a mean total length (TL) of 308 cm, were observed. Of these, 166 performed at least one or more interactions, for a total of 240 interactions with bait and the seal-shaped decoy. In Gansbaai, there is a population of transient white sharks consisting mainly of immature specimens throughout the year. Both mature and immature sharks preferred to prey on the seal-shaped decoy, probably due to the dietary shift that occurs in white sharks whose TL varies between 200 cm and 340 cm. As it is widely confirmed that white sharks change their diet from a predominantly piscivorous juvenile diet to a mature marine mammalian diet, it is possible that Gansbaai may be a hunting training area and that sharks show a discriminate food choice, a strategy that was adopted by the majority of specimens thanks to their ability to visualize energetically richer prey, after having been attracted by the odorous source represented by the tuna bait.

1. Network analysis is increasingly widespread in ecology, with frequent questions asking which nodes (typically species) interact with one another and how strong are the interactions. Null models are a way of addressing these questions, helping to distinguish patterns driven by neutral mechanisms or sampling effects (e.g. relative abundance of different taxa, sampling completeness) from deterministic biological mechanisms (e.g. resource selection and avoidance), but few ‘off the shelf’ tools are available. 2. We present econullnetr, an R package combining null modelling and plotting functions for networks, with data-export tools to facilitate its use alongside existing network analysis packages. It models resource choices made by individual consumers, enabling it to capture individual-level heterogeneity and generalising to a wider range of data types and scenarios than models applied directly to network matrices. The outputs can be analysed from the level of individual links to whole networks. 3. We describe the main functions and provide two short examples, along with the results of a benchmarking exercise to provide guidance about the statistical power and error rates. Our hope is that econullnetr provides a basis for more widespread use of null modelling to assist ecological network interpretation.

Terrestrial wildlife is being hunted for consumption by humans in the tropics at an unprecedented rate, and the often unsustainable nature of this harvest has profound implications not only for biodiversity and ecosystem function, but also for human livelihoods. Whilst the nature and impacts of this practice have been studied in numerous contexts and localities, a comprehensive treatment of the social, economic, and environmental determinants of both hunter decision-making and hunting outcomes has been lacking. In this review we discuss influences of hunting methods and effort on the types of animals caught, the efficiency of harvest, and the implications of these factors for sustainability. We highlight gaps in current understanding, and identify the most important data requirements. Our approach provides a framework for the design of future studies into wild meat hunting and its impacts, promoting the efficient targeting of priority areas of research.

This article describes a software tool called “Pursuit” that is intended to be used for both research and teaching on the topic of optimal foraging theory. The tool provides a dynamic graphical and auditory interface in which users encounter different prey animals and then must decide whether to pursue or ignore the encountered prey. Based on the characteristics of the prey in the foraging environment and the decisions of the player, each user harvests a set of prey per round and achieves a corresponding foraging return rate. Administrators of Pursuit specify the environmental parameters that determine what prey users will encounter. All environmental parameters and user decisions are tracked and logged for analysis. We created this tool for laboratory experiments, but we believe Pursuit could also be an engaging and effective teaching tool, whereby students adopt the role of forager, and through such play, experience a simulated foraging context and learn about foraging theory. Pursuit is freely available and can run on any platform that supports Java, including Mac OS, Windows, and Linux.

The use of carrion to feed spiderlings has never previously been observed in spiders. Here we show that the theridiid Theridion evexum Keyserling 1884 stored dead insectan prey for up to one week prior to the emergence of spiderlings from the egg sac, and continued to feed spiderlings dead prey for six weeks until spiderlings molted to the fourth instar. Spiderlings survived and molted on an experimental diet of exclusively rotten insects. UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biología

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:45:29Z No. of bitstreams: 1 S0074-02762001000600023.pdf: 51995 bytes, checksum: e46416e54e824eb865750c18c3c8987c (MD5) Made available in DSpace on 2013-08-22T18:45:29Z (GMT). No. of bitstreams: 1 S0074-02762001000600023.pdf: 51995 bytes, checksum: e46416e54e824eb865750c18c3c8987c (MD5) Previous issue date: 2001-08-01 Made available in DSpace on 2013-09-30T19:34:33Z (GMT). No. of bitstreams: 2 S0074-02762001000600023.pdf: 51995 bytes, checksum: e46416e54e824eb865750c18c3c8987c (MD5) S0074-02762001000600023.pdf.txt: 18705 bytes, checksum: c6d4ff356bbc186d45bef9d6c23cbc55 (MD5) Previous issue date: 2001-08-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:52:51Z No. of bitstreams: 2 S0074-02762001000600023.pdf: 51995 bytes, checksum: e46416e54e824eb865750c18c3c8987c (MD5) S0074-02762001000600023.pdf.txt: 18705 bytes, checksum: c6d4ff356bbc186d45bef9d6c23cbc55 (MD5) Made available in DSpace on 2014-05-20T13:52:51Z (GMT). No. of bitstreams: 2 S0074-02762001000600023.pdf: 51995 bytes, checksum: e46416e54e824eb865750c18c3c8987c (MD5) S0074-02762001000600023.pdf.txt: 18705 bytes, checksum: c6d4ff356bbc186d45bef9d6c23cbc55 (MD5) Previous issue date: 2001-08-01 In this study we investigated predation rates on third instar larvae of Chrysomya putoria and C. megacephala by third instar larvae of C. albiceps in a two-choice situation. The highest predation rate occurred on C. putoria larvae and this result is compared to previous experiments, in which C. macellaria larvae were present. Our results suggest that, when C. macellaria is absent C. albiceps larvae attack more C. putoria than C. megacephala larvae. Prey choice decisions and its implications for introduced and native blowflies are discussed. Universidade Estadual Paulista IB Departamento de Parasitologia Universidade Estadual Paulista IB Departamento de Parasitologia

Insectivorous birds rely on a short period of food abundance to feed their young; they must time their reproduction to match the timing of Lepidoptera larvae, their main prey. Apart from the net result (i.e. birds are timed or mistimed with respect to the food’s peak), an important aspect is the possible influence of other factors, such as the seasonality of the environment or the abundance and diversity of species contributing to the caterpillar peak, on birds’ phenology and their ability to cope well with unpredictable food supplies. In a 2-year study, we explored the seasonal variation of nestling diet in Mediterranean blue tits Cyanistes caeruleus and how reproductive parameters (nestling condition, provisioning rates) are affected by the phenology and composition of food. We also examined the influence of the synchrony between offspring needs and caterpillar peak in shaping the composition of the nestlings’ diet. We found that the effect of synchrony on nestling condition varied between years which may be partially due to differences in food peak attributes. The adequacy of birds’ timing in relation to prey phenology affected foraging decisions; those birds that were not able to correctly adjust their timing were forced to rely on less preferred prey (tortricids). In this sense, we found that relative contribution of tortricids (smaller caterpillars but easier to get) and noctuids (preferred prey but more difficult to find) to the diet influenced nestling condition and parental provisioning effort; parents performed fewer feeding events and reared heavier nestlings as the contribution of noctuids to the diet increased. The relationship between the proportion of caterpillars and nestling mass was curvilinear, whereas that parameter was negatively affected by the percentage of pupae. Our results show how changes in diet composition may contribute to explain the effect of mismatching on birds’ breeding performance.

Eurasian Oystercatchers Haematopus ostralegus ostralegus are a classic example of individual feeding specialization. Feeding specialization causes morphological differentiation in Oystercatchers’ bill shapes due to varying degrees of abrasion associated with specific handling techniques for each prey species. Consequently, the Oystercatcher’s bill shape has been used as a proxy for diet specialization, as it provides a quick and easy way to assess the diet choice of this marine top-predator. However, bill shapes of Oystercatchers are categorized visually in distinct types, while it has been argued that the relevant variation is continuous. Also, it is unclear how comparable the bill-shape classification is among studies and between the sexes and how universal bill shape–diet relationships are. Here we investigate the usefulness of bill-shape types as a proxy for diet choice in Oystercatchers, using four new and two published datasets. We show that quantitative bill-morphometrics provide no evidence that bill-shape types are discrete entities. Additionally, the dimensions of the same bill-shape type differ across studies. This difference is unlikely to be caused by methodology and might reflect subtle additional feeding specialization among birds with the same bill-shape type. Moreover, we show that the tip of the bill of males is typically 7% higher than that of females with the same bill-shape type. A higher – and probably stronger – bill tip in males may explain why males had more shellfish in their diet than females with the same bill-shape type. Finally, a literature-review shows that the exact bill shape–diet relationship differs between studies and the sexes. We conclude that the interpretation of bill-shape type as a proxy for diet choice in Oystercatchers is context dependent. We propose that quantitative bill dimensions are a better proxy for feeding specialization than bill-shape types.

Illegal hunting of wildlife is a major issue in today's society, particularly in tropical ecosystems. In this study, a total of 114 local residents from eight villages located in four wards adjacent to the northern Gonarezhou National Park, south-eastern Zimbabwe were interviewed in 2009, using semi-structured questionnaires. The study aimed to answer the following questions: (i) what is the prevalence of illegal hunting and what are commonly used hunting methods? (ii) Which wild animal species are commonly hunted illegally? (iii) What are the main reasons for illegal hunting? (iv) What strategies or mechanisms are currently in place to minimize illegal hunting? Overall, 59% of the respondents reported that they saw bushmeat, meat derived from wild animals, and/or wild animal products being sold at least once every six months, whereas 41% of the respondents reported that they had never seen bushmeat and/or wild animal products being sold in their villages and/or wards. About 18% of the respondents perceived that illegal hunting had increased between 2000 and 2008, whereas 62% of the respondents perceived that illegal hunting had declined, and 20% perceived that it remained the same. Snaring (79%) and hunting with dogs (53%) were reportedly the most common hunting methods. A total of 24 wild animal species were reportedly hunted, with African buffalo ( Syncerus caffer) (18%), Burchell's zebra ( Equus quagga) (21%), kudu ( Tragelaphus strepsiceros) (25%) and impala ( Aepyceros melampus) (27%) amongst the most targeted and preferred animal species. In addition, large carnivores, including spotted hyena ( Crocuta crocuta) (11%), leopard ( Panthera pardus) (10%) and African lion ( Panthera leo) (8%), were reportedly hunted illegally. The need for bushmeat, for household consumption (68%), and raising money through selling of wild animal products (55%) were reported as being the main reasons for illegal hunting. Strengthening law enforcement, increasing awareness and environmental education, and developing mechanisms to reduce human-wildlife conflicts will assist in further minimizing illegal hunting activities in the Gonarezhou ecosystem.