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The natural diet of two different common carp (Cyprinus carpio) phenotypes (mirror and scaly) was studied in earth ponds in the Czech Republic. The proportion of different items was assessed through analysis of gut contents in order to establish differences and similarities between the phenotypes. In addition, temporal changes through the growing season, the influence of fish weight on proportion of main items ingested and the relationship between gut content and natural food availability was also assessed. The results showed no difference in feeding behaviour between mirror and scaly carp, the two phenotypes displaying a diet overlap of around 0.8. A shift in food resources from benthic to planktonic organisms was observed between early and late summer, which was reflected in changes in electivity index for some taxa. Fish weight did not influence the proportion of organisms ingested. No correlation was found between natural food in the pond and that in the gut, any variation in diet probably reflecting the microhabitats in which individual carp choose to feed.
In the present study changes of some blood parameters of wild female yellowfin seabream (Acanthopagrus latus) caught from Persian Gulf were assayed during reproductive cycle. Altogether, 120 female A. latus (15 each month) were captured monthly from October 2010 to May 2011 from the Mussa Creek in the north-west of Persian Gulf. Blood samples were collected from caudal vein; plasma was separated and kept at -80 °C till analysis. Total protein, glucose, cholesterol, triglyceride, electrolytes, calcium, sodium, chloride, magnesium, potassium plus hepatic enzymes, Alanine Amino Transferase (ALT) and Aspartate Amino Transferase (AST), were assayed in plasma sample. Total protein and calcium increased parallel to ovarian development and decreased after spawning time. Cholesterol and triglyceride had a peak during vitellogenesis and decreased after spawning but glucose had a peak during spawning time. Most of the electrolytes (sodium, magnesium and potassium) did not show any significant changes during the reproductive cycle in A.Latus. AST reached a peak during final maturation of ovaries but ALT did not show any significant difference during different sampling times. Our findings showed that biochemical parameters could be used as indicators of physiological status during different maturation stage in this species.
The timing of egg laying by songbirds is known to be strongly affected by local climate, with temperature and precipitation being the most influential factors. However, most research to date relates only to the start of the breeding season: later records and the duration of the whole have not been taken into consideration. In the case of multibrooded species, productivity usually depends on the length of the breeding season. In this work we analysed climatic factors affecting breeding season length of an urban blackbird (Turdus merula) population. The study was conducted in two parks in the city of Szczecin, north-western Poland, spanning 14 breeding seasons since 1997. We found that over the study period, the breeding season became shorter as a result of colder springs and possibly because of warmer June-July temperatures. Our study revealed a positive relationship between breeding season length and the mean and mean minimum temperatures in April. Total precipitation in April-July also positively influenced breeding season length. The present survey confirms the influence of temperature and precipitation on the breeding season length of blackbird.
The widespread use of nest-boxes significantly improved our understanding of the ecology and behaviour of secondary cavity-nesting birds. Although former investigations showed that nest-box characteristics (e.g. physical dimensions, material) may determine where birds will roost or breed, biological consequences of the age of nest-boxes have been rarely investigated with field experiments. To test if age of cavities may influence roosting or breeding behaviour in cavity-nesting birds, we created a set-up of three experimental groups of wooden boxes with the same physical dimensions: old boxes that were occupied at least once for nesting during years prior to this study, old boxes that were never accepted for breeding during years prior to this study, and new boxes. Half of the old boxes were relocated within the study plot and replaced by new ones. Box age did not have an impact on occupation rates during the winter period, and therefore did not seem to influence where the birds roosted. However, breeders occupied the old previously unoccupied boxes less frequently than the other boxes. Moreover, birds bred much earlier in new boxes than in the old boxes that were previously never exploited. We discuss when and how cavity age can influence roosting or breeding in nest-box exploiters. Our results strongly suggest that maintenance procedures of plots where old boxes are replaced by new ones can influence how and where birds will breed.
Birds protect their nests against predators in various ways. In addition to active defence, they can hide their nests or use the protection of other species breeding nearby that actively defend the nests. Studies evaluating these strategies simultaneously are rare, especially from areas unaltered by humans. Nest predation risks were studied in a wetland bird community at Lake Baikal, Russia. The community contained several species actively defending their nests, although most were “passive defenders”. Such tactics as active defence, concealed nesting, neighbourhood nesting and coloniality were tested for their effects on predation risk. The main predators were birds, particularly carrion crows (Corvus corone). Analysis of 193 nests using multimodel inference based on Akaike's information criterion suggests the most successful tactic was active nest defence, although most birds applying this tactic build open (uncovered) nests. Passive defenders effectively reduced this risk by nest concealment and/or breeding near active defenders. Opposing patterns were found for active versus passive defenders near the most successful breeder but also a potential nest predator, the Mongolian gull (Larus mongolicus). Conservation implications emphasize support for large aggregations of active nest defenders, vegetation cover providing good nest shelter, and sufficient area of interior habitat reducing edge effects.
Birds' nesting success may vary significantly between years. Ample evidence exists that this variation is caused by temporal fluctuations in rodent populations, as rodents are important components in the diets of nest predators. The alternative prey hypothesis supposes that generalist predators switch to alternative prey (bird nests) when their main prey (rodents) is lacking, thus causing increased nest predation. According to the shared predation hypothesis, by contrast, predator density is enhanced at rodent population peaks and results in simultaneous increase in main and alternative prey predation. To evaluate these hypotheses, nest predation rate dynamics were examined using artificial nests (n = 560) and rodent abundance (2240 traps) during four breeding seasons in Central European (the Czech Republic) secondary forests. Although rodent abundance increased at the population peak by almost seven times compared to the baseline and nest predation rate also showed significant inter-year variation, the data support neither the alternative prey nor shared predation hypotheses. In rich ecosystems with complex trophic levels, predators can use many resources as alternative prey. Therefore, bird nest predation risk does not increase or decrease in periods of low rodent abundance.
The species of the genus Cimex (Heteroptera: Cimicidae) are important ectoparasites of European bats. Unlike other ectoparasites, they are attached to the body of their host only when they need to feed, otherwise they stay in refugia in bat roosts. Consequently, they are often overlooked by bat specialists and in many countries they are either unknown or poorly characterized. This study reports results from thorough investigations of bat roosts of diverse bat species in a Northwest-Southeast transect across Europe: Czech and Slovak Republics, Hungary, Serbia and Bulgaria. The distribution of Cimex lectularius follows the synanthropic habitats of its principal hosts, Myotis myotis and M. emarginatus, both Mediterranean elements of the European fauna. The climate in natural roosts (i.e. caves) inhabited by these bats in southern areas appears to restrain the presence of cimicids. In central Europe, C. pipistrelli parasitizes, beside M. myotis, many crevice-dwelling bat species indigenous to the boreal zone. However, in southern Europe, it appears only in connection with Nyctalus noctula. C. lectularius was confirmed for five host bat species and newly recorded for Rhinolophusferrumequinum, C. pipistrelli was confirmed for seven bat species and newly recorded for Myotis nattereri. The first record of C.emarginatus outside of its type locality and Myotis alcathoe as a new host are reported. The host preferences of the species of the genus Cimex are discussed.
We karyotyped six species of Microtus voles collected along the southern edge of their range in northern and western Iran. Diploid and fundamental numbers were as follows: M. socialis and M. paradoxus 2n = 62, FNa = 60, M. qazvinensis 2n = 54, FNa = 54, M. transcaspicus 2n = 52, FNa = 52, and M. mystacinus (= M. rossiaemeridionalis) 2n = 54, FNa = 54. Two cytotypes were retrieved in M. irani from its type locality: 2n = 48, FNa = 46 and 2n = 64, FNa = 62. While our results confirmed an early report of 2n = 64 for this vole, the 2n = 48 cytotype remains unexplained. Karyological variability is relatively low in social voles and chromosomal data contribute little to individual species recognition. We argue that Arvicola mystacinus De Filippi, 1865, described from Lar Valley (northeast of Tehran) is the oldest available name for 2n = 54 voles with the following synonyms: M. subarvalisMeyer, Orlov & Skholl, 1969, M. epiroticus Ondrias, 1966, and M. rossiaemeridionalis Ognev, 1924.
We examined the ecological factors influencing winter abundance of mammals in the natural deciduous forest and the Japanese larch, Larix leptolepis, plantation in Mount Maehwa, Hongcheon, South Korea. We counted the tracks of five mammal species — the Korean hare, Lepus coreanus; the raccoon dog, Nyctereutes procyonoides; the Siberian weasel, Mustela sibirica; the water deer, Hydropotes inermis and the wild boar, Sus scrofa — in the snow from November 2013 to February 2014. We showed that the mean basal area, canopy cover and shrub cover were significantly higher in the Japanese larch plantation than in the natural deciduous forest. The winter abundances of Korean hares, raccoon dogs and water deer were higher in the Japanese larch plantation than in the natural deciduous forest. The results of stepwise analysis revealed that the winter abundances of four species were significantly correlated with ≥ 1 of the habitat variables. The winter abundances of Korean hares, water deer and wild boars were significantly correlated with shrub cover. The winter abundances of Korean hares, raccoon dogs and wild boars were significantly correlated with fallen logs; and the winter abundance of water deer was significantly correlated with canopy cover. For all of the investigated species, the preferred winter habitat was the Japanese larch plantation, with dense shrub cover and high number of fallen logs. Our results indicate that for planning conservation and forest management strategies for mammal species, the preferred forest habitat variables must be taken into consideration.
In Sardinia island (Central Italy) the wild boar is originally present with an endemic subspecies, Sus scrofa meridionalis. To evaluate its demographic and reproductive characteristics, we analysed data on the harvest bags of two hunting seasons (2011–2012 and 2012–2013) in the province of Olbia-Tempio (North-Eastern Sardinia). We collected data of 325 Sardinian wild boars. Sex-ratio did not differ significantly from the theoretical distribution 1:1. We examined 175 females; thirty-five percent of them were in breeding condition, with 56 pregnant and five lactating females. Gestation was more frequent in heavier females than in the lighter ones. The mean number of foetuses per litter was 4.2 ± 1.2 (range two-seven), with no differences between the hunting seasons. There was an evidence of seasonality in reproduction period; the mating season appeared to occur primarily in late autumn and in winter, whereas farrowing mainly occurred from March to May (56 % of births), with a minimum in summer (5 % of births).
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