Martínez-Padilla, J., Redpath, S. M., Zeineddine, M., Mougeot, F. (2013), Insights into population ecology from long-term studies of red grouse Lagopus lagopus scoticus. Journal of Animal Ecology. doi: 10.1111/1365-2656.12098
Long-term studies have been the backbone of population ecology. The red grouse Lagopus lagopus scoticus is one species that has contributed widely to this field since the 1950s. This paper reviews the trajectory and profound impact that these studies have had.Red grouse research has combined long-term studies of marked individuals with demographic studies over wide geographical areas and replicated individual- and population-level manipulations. A main focus has been on understanding the causes of population cycles in red grouse, and in particular the relative importance of intrinsic (behaviour) and extrinsic (climate, food limitation and parasite) mechanisms.Separate studies conducted in different regions initially proposed either the nematode parasite Trichostrongylus tenuis or changes in male aggressiveness in autumn as drivers of population cycles.More recent experiments suggest that parasites are not a necessary cause for cycles and have highlighted that behavioural and parasite-mediated mechanisms are interrelated. Long-term experiments show that parasites and aggressiveness interact.Two outstanding questions remain to be tested experimentally. First, what intrinsic mechanism causes temporal variation in patterns of male aggressiveness? The current favoured mechanism is related to patterns of kin structuring although there are alternative hypotheses. Second, how do the dual, interacting mechanisms, affect population dynamics?Red grouse studies have had an important impact on the field of population ecology, in particular through highlighting: (1) the impact of parasites on populations; the role of intrinsic mechanisms in cyclic dynamics and the need to consider multiple, interacting mechanisms.Long-term studies have been the backbone of population ecology. This paper reviews the trajectory and impact of red grouse studies in this field. The authors highlight the impact of parasites on red grouse population dynamics, the role of intrinsic mechanisms in cyclic dynamics, and the need to consider multiple, interacting mechanisms.
Insights into population ecology from long-term studies of red grouse Lagopus lagopus scoticus
Paulina Artacho, Isabelle Jouanneau, and Jean-François Le Galliard
Physiological and Biochemical Zoology
Vol. 86, No. 4 (July/August 2013), pp. 458-469
Studies of the relationship of performance and behavioral traits with environmental factors have tended to neglect interindividual variation even though quantification of this variation is fundamental to understanding how phenotypic traits can evolve. In ectotherms, functional integration of locomotor performance, thermal behavior, and energy metabolism is of special interest because of the potential for coadaptation among these traits. For this reason, we analyzed interindividual variation, covariation, and repeatability of the thermal sensitivity of maximal sprint speed, preferred body temperature, thermal precision, and resting metabolic rate measured in ca. 200 common lizards (Zootoca vivipara) that varied by sex, age, and body size. We found significant interindividual variation in selected body temperatures and in the thermal performance curve of maximal sprint speed for both the intercept (expected trait value at the average temperature) and the slope (measure of thermal sensitivity). Interindividual differences in maximal sprint speed across temperatures, preferred body temperature, and thermal precision were significantly repeatable. A positive relationship existed between preferred body temperature and thermal precision, implying that individuals selecting higher temperatures were more precise. The resting metabolic rate was highly variable but was not related to thermal sensitivity of maximal sprint speed or thermal behavior. Thus, locomotor performance, thermal behavior, and energy metabolism were not directly functionally linked in the common lizard.
Selective Blubber Fatty Acid Mobilization in Lactating Gray Seals (Halichoerus grypus)
Aline Arriola, Martin Biuw, Mike Walton, Simon Moss, and Patrick Pomeroy
Physiological and Biochemical Zoology
Vol. 86, No. 4 (July/August 2013), pp. 441-450
During negative energy balance periods, fatty acids (FAs) are mobilized to cover the metabolic demands of the body. FAs from adipose tissue are selectively mobilized according to their carbon length (CL) and number of double bonds (DBs); however, studies in vivo have focused only on fasting and nonlactating animals. During lactation, UK gray seals fast for 18 d, mobilizing a large amount of lipid from blubber to sustain their own metabolic demands and the nutritional requirements of pups. We investigated FA mobilization in individual gray seal mothers from two UK colonies sampled in 2005 and 2006. Linear mixed-effects models were used to examine to what extent the mobilization observed from FAs in blubber can be explained as a function of FAs’ CL and number of DBs. FAs were mobilized according to their structure, such that for a given CL, mobilization increased with the number of DBs, and for a given number of DBs, mobilization decreased as CL increased. This pattern of selective mobilization was very similar between colonies, although the relative amounts of component FAs in blubber at early lactation were different between them. FAs, which are considered crucial to pup development, were mobilized more than predicted by the model. This suggests that selective mobilization of FAs is not related solely to the physicochemical characteristics of the FAs but also to the needs of a growing pup.
STARR, C. and NEKARIS, K.A.I. (2013), Obligate Exudativory Characterizes the Diet of the Pygmy Slow Loris Nycticebus pygmaeus. Am. J. Primatol.. doi: 10.1002/ajp.22171
Few primate species are known to excavate plant sources to procure exudates and other foods via active gouging. It is now apparent that slow lorises belong to this rare guild of obligate exudativorous primates. We investigate the diet of the pygmy loris (Nycticebus pygmaeus) in a mixed deciduous forest in the Seima Protection Forest, Eastern Cambodia, and attempted to determine the importance of this resource in their diet. Feeding behaviors of six females and seven males were observed using radio-tracking to facilitate follows, and nine fecal samples were collected in February–May and January–March in 2008 and 2009 respectively. We observed 168 feeding bouts, during which the animals ate exudates (76); fruits (33); arthropods (27); flower parts (21); fungi ; parts of bamboo culms ; and reptiles (1). We filmed 19 bouts of exudativory, and observed animals consuming exudates in an orthograde posture, or standing quadrupedally over the exudate source. Pygmy lorises also gouged bamboo to collect lichen and fungi, or broke open dead culms to access invertebrates. Feeding occurred on terminal tree branches (24), tree trunks (21), bamboo (13), the middle of branches , and the undergrowth (1). The fecal samples contained plant parts, small-sized arthropods (primarily Coleoptera and Lepidoptera), reptile scales, animal bones, and animal hairs. Pygmy slow lorises are morphologically specialized for processing and digesting exudates, displaying small body sizes, specialized dentitions, elongated, and narrow tongues, large caecums, short duodenums, expanded volar pads, and modified hindlimbs. These features, combined with the prevalence of exudates in their diet across seasons, and ill health when exudates are missing from their diet in captivity, points to this species being an obligate exudativore.
First Report on Circulation of Echinococcus ortleppi in the one Humped Camel (Camelus dromedaries), Sudan
Ahmed ME, Eltom KH, Musa NO, Ali IA, Elamin FM, Grobusch MP, Aradaib IE
BMC Veterinary Research 2013, 9:127 (25 June 2013)
Echinococcus granulosus (EG) complex, the cause of cystic echinococcosis (CE), infects humans and several other animal species worldwide and hence the disease is of public health importance. Ten genetic variants, or genotypes designated as (G1-G10), are distributed worldwide based on genetic diversity. The objective of this study was to provide some sequence data and phylogeny of EG isolates recovered from the Sudanese one-humped camel (Camelus dromedaries). Fifty samples of hydatid cysts were collected from the one- humped camels (Camelus dromedaries) at Taboul slaughter house, central Sudan. DNAs were extracted from protoscolices and/or associated germinal layers of hydatid cysts using a commercial kit. The mitochondrial NADH dehydrogenase subunit 1 (NADH1) gene and the cytochrome oxidase subunit 1 (cox1) gene were used as targets for polymerase chain reaction (PCR) amplification. The PCR products were purified and partial sequences were generated. Sequences were further examined by sequence analysis and subsequent phylogeny to compare these sequences to those from known strains of EG circulating globally.
The identity of the PCR products were confirmed as NADH1 and Cox1 nucleotide sequences using the Basic Local Alignment Search Tool (BLAST) of NCBI (National Center for Biotechnology Information, Bethesda, MD). The phylogenetic analysis showed that 98% (n = 49) of the isolates clustered with Echinococcus canadensis genotype 6 (G6), whereas only one isolate (2%) clustered with Echinococcus ortleppi (G5).
This investigation expands on the existing sequence data generated from EG isolates recovered from camel in the Sudan. The circulation of the cattle genotype (G5) in the one-humped camel is reported here for the first time.
Shine, R. (2013), A review of ecological interactions between native frogs and invasive cane toads in Australia. Austral Ecology. doi: 10.1111/aec.12066
Translocated from their native range in the Americas in 1935, cane toads (Rhinella marina, Bufonidae) have now spread through much of tropical and subtropical Australia. The toad’s invasion and impact have attracted detailed study. In this paper, I review information on ecological interactions between cane toads and Australian anurans. The phylogenetic relatedness and ecological similarity between frogs and toads creates opportunities for diverse interactions, ranging from predation to competition to parasite transfer, plus a host of indirect effects mediated via impacts of toads on other species, and by people’s attempts to control toads. The most clear-cut effect of toads on frogs is a positive one: reducing predator pressure by fatally poisoning anuran-eating varanid lizards. However, toads also have a wide range of other effects on frogs, some positive (e.g. taking up parasites that would otherwise infect native frogs) and others negative (e.g. eating frogs, poisoning frogs, competing with tadpoles). Although information on such mechanisms predicts intense interactions between toads and frogs, field surveys show that cane toad invasion has negligible overall impacts on frog abundance. That counter-intuitive result is because of a broad balancing of negative and positive impacts, coupled with stochastic (weather-induced) fluctuations in anuran abundance that overwhelm any impacts of toads. Also, the impacts of toads on frogs differ among frog species and life-history stages, and depend upon local environmental conditions. The impacts of native frogs on cane toads have attracted much less study, but may well be important: frogs may impose biotic resistance to cane toad colonization, especially via competition in the larval phase. Overall, the interactions between native frogs and invasive toads illustrate the diverse ways in which an invader’s arrival can perturb the native fauna by both direct and indirect mechanisms, and by which the native species can curtail an invader’s success. These studies also offer a cautionary tale about the difficulty of predicting the impact of an invasive species, even with a clear understanding of mechanisms of direct interaction.
van der Meer, E., Rasmussen, G. S.A., Muvengwi, J. and Fritz, H. (2013), Foraging costs, hunting success and its implications for African wild dog (Lycaon pictus) conservation inside and outside a protected area. African Journal of Ecology. doi: 10.1111/aje.12092
When selecting a habitat, animals utilize habitat in which they yield the highest rate of energy. Differences in foraging costs and hunting success are therefore likely to affect habitat choice. In a previous study, we showed that African wild dog (Lycaon pictus) packs with territories inside Hwange National Park (HNP), over the course of several years, moved their territories into the buffer zone outside HNP, where reproductive success was higher but anthropogenic mortality exceeded natality. In this study, based on long-term radio-telemetry data from 22 African wild dog packs, we analysed whether differences in foraging costs and hunting success could have contributed to this territorial drift. Taking seasonality and pack size into account, we determined foraging costs (foraging distance and chase distance) and hunting success (successful or failed chase) inside and outside HNP. Although we observed no difference in foraging costs, hunting success was higher outside HNP, which is likely to have contributed to the territorial drift into the buffer zone outside the protected area. This study shows the importance of taking factors affecting hunting success into account in the conservation strategy of African wild dogs.
Wan Xinrong, Xinjie Zhang, Yingjun Huo, Guiming Wang, Weather entrainment and multispectral diel activity rhythm of desert hamsters, Behavioural Processes, Available online 25 June 2013, ISSN 0376-6357, http://dx.doi.org/10.1016/j.beproc.2013.06.011.
The circadian rhythm of animals is an adaptation to predictable variation in environmental conditions. Multiple internal oscillators may allow animals to cope with environmental oscillations in different frequencies. Heat stress and dramatic differences between night and day temperatures are the main selective pressures of the diel activity of desert mammals, particularly small-sized rodents. We tested the hypotheses that the diel activities of desert hamsters (Phodopus roborovskii) would be entrained by ambient humidity and temperature. We predicted that increases in night temperature and humidity would improve the propensity to perform activities of the hamster. We observed hourly activities of desert hamsters under semi natural conditions for 24 consecutive hours, with seven replicates in 7 different days. We fit generalized linear mixed models to observed proportions of active hamsters, temperatures, and relative humidity. Observed diel activities of desert hamsters consisted of three harmonic oscillations in the periodicities of 24 hours, 12 hours, and 6 hours, respectively. Furthermore, probabilities to perform activities were positively related to night temperature and humidity. Therefore, the diel activities of desert hamsters are synchronized by atmospheric humidity, temperatures, and environmental cues of ultradian fluctuations.
Remy Manuel, Jeroen Boerrigter, Jonathan Roques, Jan van der Heul, Ruud van den Bos, Gert Flik, Hans van de Vis
Stress in African catfish (Clarias gariepinus) following overland transportation
Fish Physiology and Biochemistry June 2013
Of the many stressors in aquaculture, transportation of fish has remained poorly studied. The objective of this study was therefore to assess the effects of a (simulated) commercial transportation on stress physiology of market-size African catfish (Clarias gariepinus). Catfish weighing approximately 1.25 kg were returned to the farm after 3 h of truck-transportation, and stress-related parameters were measured for up to 72 h following return. Recovery from transportation was assessed through blood samples measuring plasma cortisol, glucose and non-esterified fatty acids (NEFA) and gill histology. Also, the number of skin lesions was compared before and after transport. Pre-transport handling and sorting elevated plasma cortisol levels compared to unhandled animals (before fasting). Plasma cortisol levels were further increased due to transportation. In control fish, plasma cortisol levels returned to baseline values within 6 h, whereas it took 48 h to reach baseline values in transported catfish. Plasma glucose and NEFA levels remained stable and were similar across all groups. Transported catfish did not, on average, have more skin lesions than the handling group, but the number of skin lesions had increased compared to unhandled animals. The macroscopic condition of the gills was similar in control, transported and unhandled catfish; however, light microscopy and immunohistochemistry revealed atypical morphology and chloride cell migration normally associated with adverse water conditions. From our data, we conclude that transportation may be considered a strong stressor to catfish that may add to other stressors and thus inflict upon the welfare of the fish.
Zootaxa 3682 (2): 277–304 (27 Jun. 2013)
Two new species of Proceratophrys Miranda-Ribeiro, 1920 (Anura; Odontophrynidae) from the Atlantic forest, with taxonomic remarks on the genus
PEDRO HENRIQUE DOS SANTOS DIAS, RENATA CECÍLIA AMARO, ANA MARIA PAULINO TELLES DE CARVALHO-E-SILVA & MIGUEL TREFAUT RODRIGUES
We describe two new species of Proceratophrys allied to the P. appendiculata species complex by the presence of single and long palpebral appendages and a triangular rostral appendage. Proceratophrys izecksohni sp. nov. is characterized by having small to medium size (SVL 32.1–54.2 mm in males), elongated hindlimbs (thigh length plus tibia length corresponding to more than 90% of snout-vent length), a broad head (head width corresponding to 55% of the snout-vent length), and by the light brown gular region and a cream colored ventral surface with scattered brown dots. Proceratophrys
belzebul sp.nov. is characterized by its medium size (SVL 40.5–51.3 mm in males), by the absence of contact between the nasals bones and between the nasals and frontoparietals, by a very reduced iliac projection, by having frontoparietal bones very depressed and broad rostrally, by the smooth surface of the squamosal and nasal, by shallow, inconspicuous ventral pits on the maxillae, and by the females presenting the gular region dark brown. The two new species were previously confused with P. appendiculata for which we provide a new diagnosis. A molecular analysis based on mitochondrial and
nuclear genes recovers a monophyletic Proceratophrys with high support, and the two new species in a clade with P. appendiculata and P. tupinamba. The data also reinforce the idea that the species groups presently admitted to the genus are not monophyletic.
Bishop, A. L. and Bishop, R. P. (2013), Resistance of wild African ungulates to foraging by red-billed oxpeckers (Buphagus erythrorhynchus): evidence that this behaviour modulates a potentially parasitic interaction. African Journal of Ecology. doi: 10.1111/aje.12093
Field observations of the interactions between red-billed oxpeckers (Buphagus erythrorhynchus) and wild ungulates in Nakuru National Park, Kenya, revealed that specific hosts frequently attempted to manipulate oxpecker foraging. This involved a repertoire of behaviour collectively referred to as resistance behaviour, and often resulted in the oxpeckers either changing their position on the host’s body or departing. Cape buffalo (Syncerus caffer), the most frequently used host, performed little resistance behaviour. Waterbuck (Kobus ellipsiprymnus) were also popular oxpecker hosts, but frequently exhibited vigorous resistance behaviour. Impala (Aepyceros melampus), the third most widely used host species, also utilized resistance behaviours, but allowed a greater proportion of oxpeckers to forage without disturbance. The suite of resistance behaviours employed by waterbuck, impala and also the consequences for oxpecker foraging, differed significantly. Our data suggest that the oxpecker–ungulate interactions in the field are more complex than previously realized with resistance behaviour regularly employed by selected mammalian host species.
Cornejo, J., Dierenfeld, E.S., Bailey, C.A. and Brightsmith, D.J. (2013), Nutritional and physical characteristics of commercial hand-feeding formulas for parrots. Zoo Biol.. doi: 10.1002/zoo.21079
Hand-rearing is a common practice for the propagation of captive psittacines, however, research on their nutrition is limited and the requirements of growing chicks are not well understood. The nutrition of 15 commercially available parrot hand-feeding formulas was compared with the average content of the crops of free living Scarlet Macaw (Ara macao) chicks, as well as with the requirements of 6- to 12-week-old leghorn chickens. When the formulas were prepared for a 1-week-old chick, all except three maintained >90% of solids in suspension after 15 min and >60 after 30 min. On average the formulas had a similar metabolizable energy density as wild macaw crop samples. The concentration of crude protein in the formulas was higher than that of the crop sample average, while the crude fat was lower than the average crop samples. More than 50% of the formulas had concentrations of K, Mg, and Mn less than the crop sample average, and Ca and Na concentrations below the requirements established for 6- to 12-week-old leghorn chickens. For >45% of the formulas the concentrations of arginine, leucine, and methionine + cystine were below the requirements of 6- to 12-week leghorns. When commercial formulas were prepared according to the manufacturer’s instructions, the different dilutions greatly magnified the nutritional differences among them. Overall, the inconsistency in the nutrient concentrations among the formulas suggests that there is no consensus among manufacturers of the correct nutrition for growing psittacines and the industry could benefit from continued research in this area.
Zachary W. Culumber, Christian E. Bautista-Hernández, Scott Monks
Physiological stress and the maintenance of adaptive genetic variation in a livebearing fish
Evolutionary Ecology June 2013
The importance of genetic variation in evolution is well established. Yet, the mechanisms by which genetic variation—particularly variation in traits under selection—is maintained in natural populations has long been an evolutionary puzzle. Understanding individual variables driving selection and their functional mechanisms is increasingly important in the context of global change and its potential consequences for biodiversity. Here we examined intra-population performance among allelic variants of a pleiotropic locus in response to thermal stress in the variable platyfish, Xiphophorus variatus. The wild-type tailspot allele exhibited significantly lower heat tolerance than all three pattern alleles found in the population, conforming to predictions based on previously observed correlations between temperature and pattern frequencies in the wild. Furthermore, differences between tailspot pattern frequencies in adults and juveniles were broadly consistent with this trend. Thus, it appears that physiological stress and reduced performance of the wild-type allele at higher relative temperatures is a mechanism balancing its frequency in natural populations. Temperature variation and not dissolved oxygen alone, as previously reported, is likely a important abiotic variable contributing to the maintenance of adaptive polymorphism. Furthermore, our findings underscore the potential implications of rising temperatures and physiological stress for levels of genetic variation in natural populations.
Frédéric Burton, Daniel Boisclair, Prediction of the consumption rates for juvenile Atlantic salmon (Salmo salar L.) on the scale of habitat patches: Development of empirical models based on stomach contents, Limnologica – Ecology and Management of Inland Waters, Available online 27 June 2013, ISSN 0075-9511, http://dx.doi.org/10.1016/j.limno.2013.05.006.
Rivers and streams are unstable environments in which estimation of energetic costs and benefits of habitat utilization are the daunting exercise. Empirical models of food consumption may be used to estimate energetic benefits based on abiotic and biotic conditions in patches of habitat. We performed thirty daily surveys of fish stomach contents to estimate the consumption rates for juvenile Atlantic salmon (Salmo salar) in a river. The data were used to assess whether variations of daily consumption rates existed within the river, and to develop empirical models that could predict fish consumption rates using abiotic and biotic conditions as independent variables. Daily consumption rates based on stomach content surveys in the field (range: 0.15–1.49g dry/(100g wet day)) varied significantly depending on habitat patch (500–1000m2), summer period, and sampling year. Variables such as water temperature, numerical density of salmon, water depth and moon phase explained 83–93% of the variations in daily food consumption rates. Daily consumption rates tended to increase with water temperature and depth, and were also higher near a full moon. However, they tended to decrease with the numerical density of salmon. Our work suggests that empirical models based on independent variables that are relatively simple to estimate in the field may be developed to predict fish consumption rates in different habitat patches in a river.
Walker, A. M., Godard, M. J. and Davison, P. (2013), The home range and behaviour of yellow-stage European eel Anguilla anguilla in an estuarine environment. Aquatic Conserv: Mar. Freshw. Ecosyst.. doi: 10.1002/aqc.2380
The behaviour patterns of yellow-stage European eels Anguilla anguilla within the tidal waters of the rivers Frome and Piddle, and the neighbouring Poole Harbour estuary (Dorset, England) were examined from July to December using acoustic transmitters and a fixed hydrophone array.Point-to-point measures of range varied between 630 m and 4150 m, with no relationship between eel size and range. Eight eels displayed repeated circuits, travelling distances of 440 m to 5060 m over a few hours.Activity was generally, but not exclusively, nocturnal, with the start and end times closely associated with sunset and sunrise, respectively.Neither direction of travel nor average ground speed was influenced by tidal flow direction, and seasonal declines in water temperature did not appear to influence behaviours.These results on distance travelled during regular, nocturnal movements provide valuable insights into the spatial and temporal distribution of yellow eels in an estuarine environment, which can aid the design of survey programmes in terms of the range over which to deploy fishing gears and the number of nights they should be fished. These survey programmes are urgently required to estimate eel production from saline environments for national Eel Management Plans, and the subsequent implementation of effective conservation measures.The strong influence of light regime on the behaviour patterns of eels points towards control of artificial illumination (light pollution) being an important eel conservation measure in this environment, at least.
Robin M. Bernstein, Heather Drought, Jane E. Phillips-Conroy, Clifford J. Jolly
Hormonal Correlates of Divergent Growth Trajectories in Wild Male Anubis (Papio anubis) and Hamadryas (P. hamadryas) Baboons in the Awash River Valley, Ethiopia
International Journal of Primatology June 2013
Comparative investigations of hormone concentration and pattern during ontogeny can offer insight regarding the evolution of growth trajectories. Anubis (Papio anubis) and hamadryas (P. hamadryas) baboons exemplify primate populations at a crucial stage of phylogenetic divergence. Though not reproductively isolated, the species are distinguished by consistent morphological, behavioral, and physiological differences, including trajectories of growth and maturation associated with divergent male reproductive strategies. As a step toward understanding the proximate causes of these differences, we tested several hypotheses regarding the relationship of growth-regulatory hormones and binding proteins (insulin-like growth factor-I, insulin-like growth factor binding protein-3 [IGFBP-3], growth hormone binding protein, and testosterone) to growth in several measurements. We collected samples (N = 559) across 13 field seasons, from 7 different social groups. Samples came from 398 different individuals. We sampled 285 once; 76, twice; 29, three times; 5, four times; and 3, five times. Although ages at peak hormone concentrations were not significantly different, concentrations of all hormones and binding proteins measured, except testosterone, were higher in hamadryas than in anubis. All factors measured correlated positively with growth in both species, and IGFBP-3 and testosterone in particular correlated significantly with growth in all measurements. Overall, our findings suggest a role for the growth hormone/insulin-like growth factor axis in producing distinctive patterns of growth in these species.
Miha Krofel, Klemen Jerina, Franc Kljun, Ivan Kos, Hubert Potočnik, Nina Ražen, Petra Zor, Anamarija Žagar
European Journal of Wildlife Research June 2013
Comparing patterns of human harvest and predation by Eurasian lynx Lynx lynx on European roe deer Capreolus capreolus in a temperate forest
Human harvest is the most important mortality factor for wild ungulates in Europe and can affect several aspects of ungulate biology. There is a growing concern about possible negative side effects of human harvest. To better understand the differences between human and natural mortality, we compared the extent, age and sex structure, nutritional condition, spatial and temporal distribution of human harvest, and natural predation by the Eurasian lynx Lynx lynx on the European roe deer Capreolus capreolus, the most abundant wild ungulate in Europe. Compared to the human harvest, lynx were less likely to kill fawns and yearlings than adults, and among adult deer, lynx were more likely to kill females. The proportion of roe deer with fat-depleted bone marrow was higher among lynx prey than among harvested animals. Average lynx kill rate was estimated to 47.8 roe deer per year, and lynx predation was considerably lower than the human harvest in the same area. While human harvest increased with higher roe deer density, lynx predation was similar across the gradient of roe deer densities. Comparison with other countries indicated that differences between human harvest and natural mortality of ungulates vary considerably in different parts of Europe. Variation in hunting practices and, even more importantly, carnivore predation may have an important role in buffering unwanted side effects of harvest of wild ungulates.
MOHAMMAD, Y., IPINJOLU, J., HASSAN, W., ALEGBELEYE, W.. Survival and growth of Clarias gariepinus (burchel 1822) fry on cultured freshwater zooplankton and decapsulated Artemia. Scientific Journal of Zoology, North America, 2, jun. 2013.
Artemia and dried zooplankton were fed to four day-old C. gariepinus fry at 3% and 5% feeding rates each as first feed. Dietary treatments were in triplicate, in a completely randomized design. Composition of mix-cultured zooplankton showed Rotifera (53.12%) to be dominant. Spawning with ovaprim at 0.5% ml/kg recorded 76% fertilization and 79% hatchability at temperature range of 28 to 300C. The best percentage survival (70.00 ±12.77) was obtained for larvae fed zooplankton at 3% feeding rate. Fry fed Artemia at 5% feeding rate, recorded specific growth rate of 12.68 ±0.64, which was significantly (P <0.05) higher than other three treatments. The condition factors ranged from 3.32 ± 0.09 to 1.73 ± 0.71 and were not significantly different (P > 0.05). Feed conversion ratio was best (0.31 ±0.09) in fry fed zooplankton at 3% feeding rate, and no significant (P >0.05) difference between the treatments. Water temperature ranged from 26.850C to 29.050C pH 7.71 to 7.83. Fry fed dried mixed-freshwater zooplankton diet had highest survival rate and the best growth rate obtained for fry fed Artemia. It was therefore concluded that Clarias gariepinus fry can be fed dried mixed-cultured freshwater zooplankton in event of scarcity and un-affordability of decapsulated Artemia.