Search

There are many documented cases of oil spillage in the Niger Delta region, southern Nigeria (West Africa). Due to both habitat characteristics and omnivorous habits, the freshwater turtles are important vertebrates species in the trophic chain. They are therefore considered to play a significant role as ecological indicators for areas subjected to oil spillage events. The aim of this study was to evaluate the effects of oil spillage and consequent pollution on the abundance, complexity and functioning of freshwater turtle communities of the Niger Delta, by comparing the turtle fauna found in two areas with similar environmental characteristics, one unpolluted and the other polluted by a case of oil spillage in 1988. A total of 510 turtle specimens belonging to four different species (Trionyx triunguis, Pelusios castaneus, Pelusios niger, and Pelomedusa subrufa) were captured in the unpolluted area, whereas 88 specimens, from two different species (P. castaneus and P. niger) were captured in the polluted area. The dominant species was P. castaneus followed by P. niger in the unpolluted area, and P. niger in the polluted area. A marked shift in habitat use was observed in one species (P. niger) after the oil spillage event. This study revealed both direct and indirect effects of oil pollution on the complexity and habitat use of Nigerian freshwater communities of turtles. The main direct effect was a considerable reduction in the specific diversity of the turtles; 50% of species were lost after oil spillage and there was a very strong decline in the numbers of turtle specimens also for those species which were able to survive the catastrophic pollution event. The shift in habitat use after oil spillage by P. niger may have a significant effect on the long-term persistence of this species, independently of the pollution effects of the oil spillage event, because it considerably reduced habitat niche separation between this species and the closely related P. castaneus, a potential competitor. It is therefore stressed that eco-ethological modifications in populations of animals subjected to catastrophic events such as oil pollution should be taken into account when evaluating the long-term effects of these devastating phenomena

Five species of chameleons were observed in the continuous forest zone of southern Nigeria: Chamaeleo gracilis gracilis Hallowell, 1842, Chamaeleo owenii Gray, 1831, Chamaeleo cristatus Stutchbury, 1837, Chamaeleo wiedersheimi Nieden, 1910, and Rhampholeon spectrum (Bucholz 1874). Many original locality records are presented for each species. One species is apparently rare and confined to montane habitats (C. wiedersheimi), another species is relatively common and its habitat is generalist (C. gracilis), and the other three species are vulnerable and limited to specific micro-habitats. Female R. spectrum had clutch sizes of two eggs each and exhibited a prolonged reproductive season with oviposition likely occurring during the late phase of the dry season. Females of both C. cristatus (clutch sizes: 11-14 eggs) and C. owenii (clutch sizes: 15-19 eggs) have a shorter reproductive season with oviposition occurring most probably at the interphase between the end of the wet season and the onset of the dry season, and female C. gracilis (clutch sizes: 14-23 eggs) appeared to exhibit two distinct oviposition periods (one at the interphase between the end of the wet season and the onset of the dry season, and one at the peak phase of the dry season). Diets of four sympatric species of chameleons consisted almost exclusively of arthropods. There were significant inter-group differences at either intra-specific level (with the females of the two best studied species, i.e. R. spectrum and C. gracilis, having a wider food niche breadth than males) or inter-specific level (with a continuum of dietary specialization from the less generalist (C. cristatus) to the more generalist (C. gracilis). However, ‘thread-trailing’ experiments indicated that activity patterns of Nigerian chameleons were relatively similar among species. The overall abundance of chameleons (as estimated from the number of specimens observed in the time unit of field effort) was relatively similar in three contrasted habitat types, but lizards were more abundant in the mature secondary forest. When greatly altered by massive logging activity, the overall abundance of chameleons in the mature secondary forest habitat declined only slightly, whereas the species diversity declined drastically. This was an effect of (i) the simultaneous extinction of three of the four species originally present in the forest plot, and of (ii) the rapid increase in abundance of a single species (C. gracilis) as a response to habitat alteration. The conservation implications of all these data are also discussed.

Decreasing in body size in snakes up to 20% of their initial size during periods of reduced food availability has induced to speculate whether these shrinkages are adaptive or not and whether they are not in squamate reptiles living in seasonally variable environments. It is found that shrinkage events are just apparent in snakes and are caused by measurement errors by experimenters.

The composition and structure of antelope assemblages were analyzed by using data from wild meat markets in three distinct study stations in the southern Niger Delta, Nigeria. The relative abundance of the different species coming into the markets was analyzed, and various diversity metrics were used to describe the different antelope communities. Sex ratios of these populations as well as the effect of season on the abundance of the various species in the markets were examined. It was observed that a single recently described species (Philantomba walteri) was the dominant species in the three localities, contributing about 70% of all the antelope individuals. The relatively low number of antelope carcasses observed in this study (less than the number of carcasses of small carnivores in the same sites) suggests that the ungulate fauna is already very depleted in the eastern Niger Delta region, with these mammals being hunted more intensely in the wet season. [ABSTRACT FROM AUTHOR]

Suitable habitats for anurans can be found in the ever‐growing tropical urban environments but anurans' adaptations to urban conditions, including their trophic ecology remain largely unknown. We studied the food habits of two generalist, widespread West African Sclerophrys adult toads: African common (Sclerophrys regularis) and Hallowell's toad (Sclerophrys maculata). The first was studied in Lomé (Togo), Cotonou (Benin) and Ikeja (Nigeria), and the second in Port Harcourt and Ikeja (both Nigeria); the latter city represents the only studied sympatric occurrence. Mean dietary overlap between population pairs was relatively high, and diet composition of the two species when sympatric did not differ significantly. Food niche width was significantly positively correlated with local rainfall in both species, and diet composition changed significantly between the dry and wet seasons. Diversity metrics revealed that females had a more diversified diet, with higher evenness and lower dominance index values than males. The diet of both species was not correlated to prey type availability, in both the wet and dry season. Both toad species targeted specific food items rather than opportunistically consume prey as observed in most anurans which may be a response to high anuran diversity typically found in the tropics or an adjustment to urban habitats. [ABSTRACT FROM AUTHOR]

Golden Eagles Aquila chrysaetos in Sardinia are clustered across the main mountain ranges of the island, with a preference for undisturbed and homogeneous inland habitats. To analyse habitat preferences of the Golden Eagle in Sardinia, Italy, at the landscape and home range spatial scales. Landscape scale habitat preferences were analysed using the 10 × 10 km Universal Transverse Mercator grid and the home range scale was based on the spatial distribution of breeding territories. Generalized linear models were fitted with three different sets of environmental predictors (topographic, bioclimatic and land use variables) to analyse the spatial distribution of Golden Eagles with a case–control design. Eagles showed a preference for rugged and elevated areas, characterized by a certain degree of humidity and surrounded by areas of forest. The distribution of Golden Eagles on this Mediterranean island was negatively affected by the occurrence of arable farmland and coastal areas, as well as by the effects of habitat fragmentation. The results of this study could contribute to future management strategies and conservation projects aimed to protect this species, and may be used to identify the most suitable conservation areas for this and other competing species, such as the Bonelli's Eagle Aquila fasciata, which is currently the subject of a reintroduction project in Sardinia. [ABSTRACT FROM AUTHOR]

Context: Dietary analyses are essential to achieve a better understanding of animal ecology. In the case of endangered species, assessing dietary requirements is crucial to improve their management and conservation. The Bonelli's eagle (Aquila fasciata) has experienced a severe decline throughout its breeding range in Europe and, in Italy, fewer than 50 pairs remain, and only in Sicily. This species is subject to major threats, including changes in landscape composition and, consequently, prey availability, which is further aggravated by the occurrence of viral diseases in the case of rabbits. Aims: To provide current data on the diet of the Bonelli's eagle in Sicily during the breeding period and to examine dietary shifts with regard to previous studies conducted in the same study area. To discuss possible implications for conservation of the Italian population of this endangered species. Methods: We used a combination of three methods, including pellet analysis, collection of prey remains, and imagery from camera-traps installed at nests, to examine the diet of 12 breeding pairs of Bonelli's eagle from 2011 to 2017. We compared this information with data collected between 1993 and 1998 in the same study area. Key results: In number, birds were the most frequently predated items (61.6%), followed by mammals (36.88%) and reptiles (1.52%). However, in terms of biomass, mammals were the main prey (65.71%), followed by birds (34.12%) and reptiles (0.17%). There was a decrease over the course of the current decade in the consumption of European wild rabbit (Oryctolagus cuniculus), which was compensated for with an increase in both dietary diversity and breadth in bird consumption, a trend not observed in the earlier study in the same region. Conclusions: Here, we provide an updated assessment of diet composition of Bonelli's eagle during the breeding period. Interestingly, we found significant differences within the study period (2011–2017) in terms of frequency of occurrence, percentage of biomass, dietary diversity and dietary breadth in a species at risk. Furthermore, we found significant differences between the two study periods in both frequency and percentage of biomass, with significant changes in the consumption of lagomorphs and birds. Implications: Our results indicated that shifts in the diet are linked to changes in prey abundance, which may be contributing to population declines in the Bonelli's eagle population in Sicily. Overall, measures aimed at increasing main dietary prey should be promoted to favour occupation of new territories and enhance vital demographic parameters (i.e. breeding success and survival rate) of Bonelli's eagle across the species range. This would be particularly important for small isolated populations such as the Sicilian one. We analysed the diet of Bonelli's eagle (Aquila fasciata) in Sicily (Italy) during the breeding season between 2011 and 2017 and compared with data collected between 1993 and 1998 in the same study area. Birds and mammals were the most important prey in terms of frequency and biomass respectively. We found significant differences in diet composition between periods, probably owing to a generalised decrease in the availability of wild rabbits. Considering the critical status of Bonelli's eagle in Italy, measures aimed at increasing populations of its main prey should be promoted. Photograph by Pascual López-López. [ABSTRACT FROM AUTHOR]

Abstract: Illegal trade in wildlife has been identified as one of the main challenges to wildlife conservation. In 2010, an illegal trade‐ring trafficking in birds of prey was uncovered in Sicily (southern Italy). This illegal trade targeted the three most endangered species in Italy: Bonelli's eagle Aquila fasciata, Lanner falcon Falco biarmicus and Egyptian vulture Neophron percnopterus, all of them long‐lived territorial raptors threatened with extinction across their European distribution. Illegal harvest primarily involved young birds and eggs taken from nests. After the discovery of these activities, surveillance camps and camera traps connected to the mobile Global System for Mobile communications network were established in nine Bonelli's eagle breeding sites in which illegal harvest was reported. Surveillance activities resulted in a sharp reduction in illegal harvest that has contributed to the recent increase in population size and number of breeding pairs of Bonelli's eagle in the island. This population represents 95% of the entire Italian population and is catalogued as Critically Endangered in this country. Importantly, our results highlight the impact of illegal harvest on the population dynamics of endangered species as demonstrated by a population viability analysis. This is particularly important in the case of insular species for which demographic recovery due to immigration from other geographic areas is unlikely. Systematic patrols by forestry police authorities, a resolute application of Convention on International Trade in Endangered Species legislation via legal punishment, and the requirement of including all live captive specimens used for falconry in an obligatory DNA data bank would contribute to reducing the risk of extinction for small populations of endangered species of birds of prey. [ABSTRACT FROM AUTHOR]

Capsule:We report a significant reduction in population size and breeding success for the Lanner FalconFalco biarmicusin Sicily, its biggest stronghold in Europe, since the latest coordinated survey. Aims:To provide updated information on current population size of Lanner Falcon in Sicily and to compare breeding parameters with those obtained in previous studies. Methods:We performed an intensive coordinated field survey and literature review of breeding success parameters across the species range. Results:Overall, we monitored 126 territories throughout Sicily where the species had been reported in the last 15 years. Lanner Falcons were present only in 60 of them. Mean nest productivity (± standard deviation) was 1.09 ± 1.18 fledged young/checked pairs, flight rate was 2.22 ± 0.52 fledged young/successful pairs and breeding success was 49.0%. Conclusions:Indirect measures aimed at preventing abandonment of occupied territories should be applied, for instance by developing a network of priority areas and slowing down degradation of the pseudo-steppe habitats by agri-environmental schemes. Additionally, direct measures aimed at preventing nest robbery, including the organization of nest guarding activities, and reduction of anthropogenic disturbance and illegal shooting, must be encouraged in order to avoid territory abandonment. [ABSTRACT FROM PUBLISHER]

Knowledge of juvenile dispersal is important for understanding population dynamics and for effective conservation, particularly of geographically isolated raptor populations. Here, we report the first documented case of a long-distance movement of an Egyptian VultureNeophron percnopterusfrom the French population to Sicily. This observation opens a new perspective for the conservation of the small and endangered Sicilian population of this species, providing evidence that persistence of the Italian population may be aided by new input from other countries. [ABSTRACT FROM PUBLISHER]

Selective seed consumption by harvester ants may be affected by several seed attributes, amongst which seed size and environmental availability play a prominent role. In the present study, we considered the effects of seed size and seed availability on the coexistence and diet preference of twoMessorspecies (Messor wasmanniandMessor minor).M. wasmannicolonies collected the most abundant resource in the environment, grass seeds (Poaceae), according to their availability whilstM. minorshowed a nonselective process. In addition, the two ant species showed a different seed size preference, withM. wasmanniadopting a selective strategy andM. minora generalist strategy. However, competition for foraging resources between the two ant species (assessed by null model algorithms) seems not to affect their foraging behaviour. The lack of a competitive structure within the ant assemblage suggests, in fact, that resources are not a limiting factor for species coexistence. [ABSTRACT FROM AUTHOR]

In Amphibians, both positive and negative correlations between activity and full moon phase have been observed. In this study, we present data for two anuran species (Hyla intermedia and Rana dalmatina) studied in a hilly Mediterranean area of central Italy. We analysed, in a two-year survey, the relationships between the number of egg clutches laid each night and the moon phases by means of circular statistics. Moreover, the studied species exhibited clear oviposition site selection behaviour influenced, at least in H. intermedia, by moon phases. We observed the occurrence of an avoidance effect by amphibians for oviposition and specific egg-laying behaviour during moon phases around the full moon. This apparent lunar phobia was evident in both species when yearly data were pooled. On the other hand, while this pattern continued to be also evident in H. intermedia when single years were considered, in R. dalmatina it stood just in one year of study. Nonetheless, during cloudy nights, when moonlight arriving on the ground was low, the frogs' behaviour was similar to that observed in new moon phases. We interpreted the observed pattern as an anti-predatory strategy. Overall, comparisons between our own study and previous research suggest that there was insufficient evidence to establish any unequivocal patterns and that further research in this regard is needed. [ABSTRACT FROM AUTHOR]

African manatees (Trichechus senegalensis) and crocodiles are threatened species in parts of their range. In West Africa, crocodiles may constitute the main predators for manatees apart from humans. Here, we explore the macro-habitat selection of manatees and two species of crocodiles (West African crocodiles Crocodylus suchus and dwarf crocodile Osteolaemus tetraspis) in the Niger Delta (Nigeria), testing the hypotheses that (i) manatees may avoid crocodiles in order to minimize risks of predation, and (ii) the two crocodile species do compete. The study was carried out between 1994 and 2010 with a suite of different field techniques.We observed that the main macro-habitat types were freshwater rivers and coastal lagoons for manatees, mangroves forWest African crocodiles, and rivers and creeks for dwarf crocodiles, with (i) the three species differing significantly in terms of their macro-habitat type selection, and (ii) significant seasonal influence on habitat selection of each species. Null models for niche overlap showed a significantly lower overlap in macro-habitat type use between manatee and crocodiles, whereas the two crocodiles were relatively similar. Null model analyses did not indicate any competitive interactions between crocodiles. On the other hand, manatees avoided macro-habitats where crocodiles, and especially West African crocodiles, are abundant. [ABSTRACT FROM AUTHOR]

The interactive-versus-isolationist hypothesis predicts that parasite communities should be depauperated and weakly structured by interspecific competition in amphibians. A parasitological survey was carried out to test this hypothesis using three anuran species from Nigeria, tropical Africa (one Bufonidae; two Ranidae). High values of parasite infection parameters were found in all three species, which were infected by nematodes, cestodes and trematodes. Nonetheless, the parasite communities of the three anurans were very depauperated in terms of number of species (4 to 6). Interspecific competition was irrelevant in all species, as revealed by null models and Monte Carlo permutations. Cluster analyses revealed that, in terms of parasite community composition, the two Ranidae were similar, whereas the Bufonidae was more different. However, when prevalence, intensity, and abundance of parasites are combined into a multivariate analysis, each anuran species was clearly spaced apart from the others, thus revealing considerable species-specific differences in terms of their parasite communities. All anurans were generalists and probably opportunistic in terms of dietary habits, and showed no evidence of interspecific competition for food. Overall, our data are widely consistent with expectations driven from the interactive-versus-isolationist parasite communities hypothesis. [ABSTRACT FROM AUTHOR]

The article discusses a study which investigated the decline of snake populations in several countries, including Great Britain, France, Italy, Nigeria and Australia. Data from studies of geographically widespread snake populations were used by the researchers. Among the snake species studied were Coronella austriaca, Natrix natrix, and Vipera aspis. It was found that the snake population decline was caused by habitat quality deterioration, prey availability and climatic changes.

The ecological correlates of dorsal colour pattern polymorphism were studied along the transition zone between two supposed subspecies ( = colour pattern types in this article) of the common wall lizard, Podarcis muralis, in a hilly area of Latium, Central Italy. In this area two supposed subspecies, i.e. P. m. brueggemanni and P. m. nigriventris, are known to occur. Lizards were studied along 500 m long transects within three different habitat types, i.e. wood, wall, and bushy pasture. A total of 279 adult lizards (154 males, 125 females) were examined. Three colour morphs were observed at each site, i.e. brueggemanni type (brown-green upper parts), nigriventris type (black-green upper parts), and a colour morph intermediate between the two. The distribution and abundance of brueggemanni and nigriventris colour morphs was clearly non-random across habitat types: brueggemanni was abundant in walls and bushy pastures, and nigriventris in wood. To explain the observed pattern we tested the hypothesis of a differential predation exposure by the various colour morphs in different habitats by analysing the differences between colour morph frequencies of lizards with intact tail and with broken/regenerated tail in the various habitats of the study area. Our analysis would not support the differential predation-risk hypothesis, because the frequency of individuals with broken tails was very similar in the three colour morphs among different habitats. [ABSTRACT FROM AUTHOR]

Urban areas are primary causes of species' range fragmentation and reduction. However, relatively few studies have attempted to describe the habitat variables influencing the diversity and conservation of amphibians and reptiles, particularly in Mediterranean Europe and in large metropolitan areas. We explored this broad conservation ecology problem by studying the richness and diversity patterns in relation to a suite of six independent habitat variables in Rome, one of the most ancient cities of the world. We considered all the green remnant areas ( n=62) of Rome, ranging 1 to >1000 ha in size, which are interspersed within a sea of urbanized matrix. A total of 10 amphibian and 15 reptile species were studied. Their presence/absence patterns were assessed and the effects of the various habitat variables on each species were predicted by a logistic regression model. A total of 1261 presence records (404 amphibians and 857 reptiles) were analysed. Fragment size and wood size within each fragment did correlate significantly with the species richness of both amphibians and reptiles, and there was a clear threshold effect after 50 ha of wooded surface. The presence of water bodies positively affected the species distribution. One amphibian and three reptiles inhabited exclusively fragments >50 ha. The distance from the centre did not affect fragment species richness. The presence of most species of both amphibians and reptiles was positively influenced by the irregular versus circular shape of the wooded area. The legal protection of a given area did not influence the observed patterns but the total number of sheltered species. Overall, our study suggests that, in order to maintain the current diversity and population viability, it is necessary, in addition to water bodies' maintenance, to (1) preserve the wooded landscapes over 50 ha; (2) promote irregularly shaped increases in the wood surface; (3) maintain ecotonal boundaries. [ABSTRACT FROM AUTHOR]

The food niche partitioning of four species of house snakes (Lamprophis fuliginosus, L. olivaceus, L. lineatus, and L. virgatus) was studied in suburban areas of south-eastern Nigeria, West Africa. Snakes were captured in the field, and their stomach contents were obtained by forced-squeezing of the ingested bolus. Pseudo-community analysis and Monte Carlo simulations, by two different algorithms, were used to investigate whether the community under study was randomly assembled along the trophic niche axis. Four hundred and thirty snake individuals were captured: 52 out of 133 L. fuliginosus (32.1%), 31 of 126 (24.6%) L. lineatus, 30 of 108 (27.8%) L. virgatus, and 20 of 63 (31.7%) L. olivaceus had identifiable food contents in the stomach. Lamprophis fuliginosus appeared as the more generalist species, L. lineatus showed some preference for lizards and frogs, L. virgatus for small mammals (rodents and shrews), and L. olivaceus for nestling birds and small mammals. However, null models showed that the community organization was random along the food niche axis by both the randomization algorithms used in this paper. Thus, we concluded that these four snake species do not partition either the quality or the number of the available resources. [ABSTRACT FROM AUTHOR]

Dog attacks on adders; a comment on Worthington-Hill & Gill (2019) When one of us (TM) used plasticine models to investigate predation on juvenile grass snakes, the models were frequently nibbled by small rodents (Madsen, [2]). Using plasticine models, in our view, constitutes an adequate way to investigate predation caused by visually hunting snake predators, but not of predation caused by predators primarily relying on olfactory cues. [Extracted from the article]

The Hermann's tortoise ( Testudo hermanni ) is increasingly threatened in Western Europe and in Italy because of habitat loss, pollution, and illegal removal of free‐ranging individuals for the pet trade. Hence, the conservation and appropriate management of the various populations is mandatory, and the few remnant, isolated populations inhabiting urban parks and heavily altered landscapes may be particularly important. An urban population of Hermann's tortoises was studied by capture–mark–recapture procedures in an ‘urban green area’ in Rome (‘Insugherata’ Natural Reserve), between March 2001 and October 2005. A spatial modelling approach (logistic regression, with forward stepwise addition model) was developed to investigate which proximate landscape factors influenced the presence/absence of the tortoises. Eight different variables were considered for this model. We found that a single variable (SHRUBS, i.e. Mediterranean dry macchia‐like vegetation) was positively correlated to the presence of tortoises, and one to their absence (ECOTONE, i.e. ecotone area constituted by different types of shrubs growing on a relatively wet substratum). The tortoise activity deviated significantly from the null hypothesis of an equal activity throughout the year, with the higher peaks of activity in May, June, and August, and reduced activity in March and April. The conservation implications of our study were also discussed. [ABSTRACT FROM AUTHOR]

Home range and nesting habitat were studied in two sympatric pelomedusid terrapins (Pelusios niger and Pelusios castaneus) from two study areas in the Niger Delta (Nigeria, West Africa), one with pristine habitat conditions and one which was polluted by a oil spill event some years before. Seventy-seven individuals (38 P. niger and 39 P. castaneus) were radiotracked, each for more than 60 days, and their home range was calculated by the minimum convex polygon method, with 95% of the point locations per individual. The mean home range size of females was significantly larger in the polluted area than in the pristine area in both P. niger and P. castaneus, and the mean home range size of female P. niger was significantly larger than that of female P. castaneus in the polluted area, but not in the pristine area. The mean home range size of males was significantly larger in the polluted area than in the pristine area in P. niger but not in P. castaneus, and the mean home range size of male P. niger was significantly larger than that of male P. castaneus in the polluted area but not in the pristine area. Radiotracked females of both species showed a clear preference for nesting sites situated along ponds and not along the banks of the river, on sandy soil, often with abundant vegetation around. Some females of both species deposited their eggs at greater distances from water bodies in the polluted area than in the pristine area. The comparative evidence of these patterns indicates consistent responses of the two species to the altered habitat, which further supports the general hypothesis that habitat pollution has seriously affected the ecological strategies of these terrapin species. [ABSTRACT FROM AUTHOR]

The theoretical and empirical causes and consequences of rarity are of central importance for both ecological theory and conservation. It is not surprising that studies of the biology of rarity have grown tremendously during the past two decades, with particular emphasis on patterns observed in insects, birds, mammals, and plants. I analyse the patterns of the biology of rarity by using a novel model system: snake communities worldwide. I also test some of the main hypotheses that have been proposed to explain and predict rarity in species. I use two operational definitions for rarity in snakes: Rare species (RAR) are those that accounted for 1% to 2% of the total number of individuals captured within a given community; Very rare species (VER) account for ≤ 1% of individuals captured. I analyse each community by sample size, species richness, continent, climatic region, habitat and ecological characteristics of the RAR and VER species. Positive correlations between total species number and the fraction of RAR and VER species and between sample size and rare species in general were found. As shown in previous insect studies, there is a clear trend for the percentage of RAR and VER snake species to increase in species-rich, tropical African and South American communities. This study also shows that rare species are particularly common in the tropics, although habitat type did not influence the frequency of RAR and VER species. This analysis also confirms the commonly accepted ecological hypothesis that body size and rarity are clearly and widely correlated in natural animal communities. However, in snake communities there is often an association between large and small species among the rare species, and a tendency for ophiophagous species to be rare. In addition, there was no support for the hypothesis that rare species should be typically phylogenetically primitive. The hypothesis that species with narrower realized ecological niches are more likely to be rare or very rare is supported by the evidence presented here on snake communities. In general, this study shows that snakes may make "model organisms" for studies on the biology of rarity. [ABSTRACT FROM AUTHOR]

Presents ecological data on the Goldie's tree cobra , Pseudohaje goldii in southern Nigeria. Frequency of rainy days per month and mean monthly relative humidity at a locality of southern Nigeria, where tree cobras were captured; Local distribution of the tree cobras; Habitat and body size characteristics.

The feeding relationships of four sympatric, ecologically nearly unknown, tree frogs of southern Nigeria (Hyperolius sylvaticus, H. guttulatus, H. fusciventris burtoni, and H. concolor) were studied during both the dry and the rainy seasons. Stomach contents were obtained by stomach flushing. The largest species were H. guttulatus and H. concolor, whereas the other two species were of smaller average size. A statistically significant sexual size dimorphism was observed in H. guttulatus, H. concolor, and H. sylvaticus (in all species the females were larger), but not in H. fusciventris. In all four species, the frequency of animals with empty stomachs was significantly lower during the rainy season than during the dry season. The four frog species were mainly arthropodeating: Araneidae and Blattoidea were preyed upon mainly by the two largest species, Acarina and Lepidoptera were taken mainly by the two smaller species, and Diptera and Formicoidea were eaten frequently by all species. The diet composition was similar between seasons in three of the four species, and H. guttulatus was the only species showing considerable diet variation between seasons. We concluded that 1) the intensity of interspecific competition should be particularly high between the two larger species on the one hand, and between the two smaller species on the other hand; and 2) the intensity of the interspecific competition should be relatively constant throughout the year. [ABSTRACT FROM AUTHOR]

Deals with the aspects of the ecology of a population of Causus maculatus from southern Nigeria. Examination of the population structure, food habits and reproductive ecology of a free-living population from a swamp rainforest-plantation mosaic area; Food items found in the stomach of the viperids; Prefered prey of Causus maculatus.

Focuses on a study which investigated the reproductive strategies, growth rates, survival and the life-history traits of Savi's pine vole (Microtus savii). Materials and methods; Characteristics of the study population; Pattern of reproductive cycle of the species; Results and discussion.

Abstract: Twenty-eight fish muscle specimens from the main water bodies of the Campania Region were analyzed in our laboratory. On average, results showed a low contamination by PCDDs+PCDFs and a relatively more important presence of DL-PCBs. All specimens were compliant with EU regulatory maximum levels. Cumulative PCDD+PCDF+DL-PCB concentrations (TEQTOT) were comprised in the range 0.223–11.4 pgWHO97–TEQg−1 fresh weight (fw). DL-PCB contribution to TEQTOT was on average greater than 86% (range, 50.2–97.1%). The cumulative concentrations of 30 non-dioxin-like PCB congeners (Σ30(NDL-PCBs)) and of the six indicators (Σ6(NDL-PCBs)) were respectively in the ranges 3.30–515 and 1.30–195ngg−1 fw. The hybrid clustering approach adopted to analyze the sample-specific congener profiles indentified the main analytical patterns present in the database and, in particular, two main diverse exposure macro-areas that seem to exist north and south of the city of Naples. The distribution of PCDD and PCDF congeners among different species showed significant variations from chub (Leuciscus cephalus), characterized by a higher proportion of low-chlorinated congeners (e.g. 2,3,7,8-T4CDD), to eel (Anguilla anguilla), whose contamination consisted mainly of highly chlorinated congeners (e.g. O8CDD). To have a more complete perspective in relation to the contaminants present in the environment, the study suggestion is to use benthic as well as pelagic species to obtain an integrated characterization of fish tissue contamination. [Copyright &y& Elsevier]

Abstract: Food habits and daily activity patterns were studied in sympatric populations of the lizards Psammodromus algirus and Acanthodactylus erythrurus (Lacertidae) from the Parc National d’El Kala, north-eastern Algeria. In this area, these two species inhabited nearly the same microhabitats and were similar in terms of body length and weight. Both species were insectivorous, and fed primarily upon Coleoptera, Formicidae, and Diptera. The interspecific diet overlap was very high in terms of both the total number of prey items and the per cent of lizards containing a given food type. Null model analysis by Monte Carlo simulations (using the RA2 and RA3 algorithms) revealed that the high diet overlap values were not produced by chance. Daily activity patterns differed intraspecifically depending on the season, and interspecifically during both spring and summer. It is possible that the interspecific differences in daily activity patterns may help facilitating coexistence of the two study species. The high diet overlap may depend on the convergent eco-physiological needs of these two species in the arid environment, which forces them to apply a similar foraging strategy, i.e. preying on a few abundant and easily found prey sources. [Copyright &y& Elsevier]

The ecological patterns of anthropogenic mortality of snakes in the Niger Delta (southeastern Nigeria), as well as factors that attract or force snakes into human settlements, are investigated in this paper. The snake species richness in suburban environments of the Niger Delta is remarkable, and includes about 36% of the species presently known from the area as a whole. The proportion of dangerous species is low. Anthropogenic mortality rates stood at a conservative mean estimate of 0.110 snakes/effort hour, while the mortality frequency peak occurred in the rainy month of June (0.559 snakes/effort hour). This mortality peak coincided with the onset of the inundation period of the swamps. The flooding of their forest habitat, and the presence of abundant food supply and shelters seem to be the main factors favoring the establishment of snake populations in urban environments. About 50% of snakes were killed intentionally by people, but vehicles and trapping with snares (set for mammals) were also important causes of mortality. The ecological correlates of the seasonal variations in mortality rates are also discussed. [ABSTRACT FROM AUTHOR]