Search results for "ck"

The "Tracked Roaming Transect" and distance sampling methods increase the efficiency of underwater visual censuses.

2018

Underwater visual census (UVC) is the most common approach for estimating diversity, abundance and size of reef fishes in shallow and clear waters. Abundance estimation through UVC is particularly problematic in species occurring at low densities and/or highly aggregated because of their high variability at both spatial and temporal scales. The statistical power of experiments involving UVC techniques may be increased by augmenting the number of replicates or the area surveyed. In this work we present and test the efficiency of an UVC method based on diver towed GPS, the Tracked Roaming Transect (TRT), designed to maximize transect length (and thus the surveyed area) with respect to diving …

New national and regional bryophyte records, 67

2021

Bulgaria. Samokov Region, Rila Mountains, Rila National Park, N slopes of peak Deno, on granite slabs and scree, collected with occasional sporophytes, 42.19709°N, 23.60322°E, 2780 m a.s.l, 17 September 2019, leg./det. R. Natcheva s.n. (SOM 9811-B). This arctic-alpine species has a north Holarctic circumpolar distribution and this is the first report of Andreaea blyttii for SE Europe. It is its southernmost locality and extends its range further south in Europe. The Rila Mountains are the highest in the Balkan peninsula and A. blyttii was found near the highest summit (Mussala, 2925 m a.s.l.). In Bulgaria the genus Andreaea is also represented by A. alpestris (Thed.) Schimp. and A. rupestri…

Weak effects of geolocators on small birds: A meta-analysis controlled for phylogeny and publication bias

2020

Abstract Currently, the deployment of tracking devices is one of the most frequently used approaches to study movement ecology of birds. Recent miniaturization of light‐level geolocators enabled studying small bird species whose migratory patterns were widely unknown. However, geolocators may reduce vital rates in tagged birds and may bias obtained movement data. There is a need for a thorough assessment of the potential tag effects on small birds, as previous meta‐analyses did not evaluate unpublished data and impact of multiple life‐history traits, focused mainly on large species and the number of published studies tagging small birds has increased substantially. We quantitatively reviewe…

Territoriality versus flocking in the Zenaida dove (Zenaida aurita): resource polymorphism revisited using morphological and genetic analyses.

2011

11 pages; International audience; The term “resource polymorphism” refers to the existence of alternative phenotypes in relation to resource use, as a result of disruptive selection. Evidence for resource polymorphism is widespread in fish but remains scarce in birds. Although Zenaida Doves (Zenaida aurita) usually defend year-round territories, doves on Barbados can also be observed foraging at seed-storage sites in large flocks with little, if any, inter-individual aggression. On the basis of morphological variation, it has been suggested (Sol et al. 2005) that this represents a case of resource polymorphism, primarily driven by competition for territories. Using new data, we revisited th…

Sexing birds using discriminant function analysis: a critical appraisal.

2011

9 pages; International audience; Discriminant function analysis (DFA) based on morphological measurements is a quick, inexpensive, and efficient method for sex determination in field studies on cryptically monomorphic bird species. However, behind the apparent standardization and relative simplicity of DFA lie subtle differences and pitfalls that have been neglected in some studies. Most of these concerns directly affect assessment of the discriminant performance, a parameter of crucial importance in practice because it provides a measure of the quality of an equation that may be used in later field studies. Using results from 141 published studies and simulations based on a large data set …

2-methylthiazolidine and 4-ethylguaiacol, male sex pheromone components of the cockroach Nauphoeta cinerea (Dictyoptera, Bladeridae) : A reinvestigat…

1992

49 ref.; International audience; In Nauphoeta cinerea, male calling behavior is associated with sex pheromone release by the sternal glands. The male pheromone that attracts females from a distance is a mixture of 2-methylthiazolidine and 4-ethylguaiacol. It is active at very low concentrations, 0.05 and 0.01 ng, respectively. Two other compounds, 3-hydroxy-2-butanone and 2-methyl-2thiazoline, act at close range, keeping the female in the vicinity of the male. The function of the volatile pheromone and those of previously described contact pheromones are discussed in regard to their possible involvement in the establishment of male dominant-subordinate relationships.

Study of the growth of herbicide-resistant black-grass populations

1991

International audience

Key carabid species drive spring weed seed predation of Viola arvensis

2020

Estimating the abundance of burrow-nesting species through the statistical analysis of combined playback and visual surveys

2016

Cadmium-induced oxidative damage and protective action of fractioned red beet (Beta vulgaris) root juice in chickens

2018

Article Cadmium (Cd) is one of the most dangerous environmental bioaccumulative pollutants that affects many organs in humans and animals. Present investigation was conducted to evaluate the protective effect of fractioned red beetroot juice on Cd - induced oxidative stress in chickens. The named red beetroot juice fraction (BJF) was received by juice ultrafiltration. Per oral administration of BJF for 10 days followed by dietar y Cd exposure (50 mg kg - 1 of diet) was evaluated in the in vivo experiments in chickens. The prominent increase of Cd concentration in blood plasma, liver and kidney provoked the rise of oxidative processes activity in organs. BJF treatment attenuated the Cd - ind…