Cache and carry: hoarding behavior of arctic fox

Food-hoarding animals are expected to preferentially cache items with lower perishability and/or higher consumption time. We observed arctic foxes (Alopex lagopus) foraging in a greater snow goose (Anser caerulescens atlanticus) colony where the main prey of foxes consisted of goose eggs, goslings, and lemmings (Lemmus and Dicrostonyx spp.). We recorded the number of prey consumed and cached and the time that foxes invested in these activities. Foxes took more time to consume a goose egg than a lemming or gosling but cached a greater proportion of eggs than the other prey type. This may be caused by the eggshell, which presumably decreases the perishability and/or pilfering risk of cached eggs, but also increases egg consumption time. Arctic foxes usually recached goose eggs but rarely recached goslings or lemmings. We tested whether the rapid-sequestering hypothesis could explain this recaching behavior. According to this hypothesis, arctic foxes may adopt a two-stage strategy allowing both to maximize egg acquisition rate in an undefended nest and subsequently secure eggs in potentially safer sites. Foxes spent more time carrying an egg and traveled greater distances when establishing a secondary than a primary cache. To gain further information on the location and subsequent fate of cached eggs, we used dummy eggs containing radio transmitters. Lifespan of primary caches increased with distance from the goose nest. Secondary caches were generally located farther from the nest and had a longer lifespan than primary caches. Behavioral observations and the radio-tagged egg technique both gave results supporting the rapid-sequestering hypothesis.     

Filtering effect of wind flow turbulence on atmospheric pollutant dispersion

This paper presents a model for coupling the statistics of wind velocity distribution and atmospheric pollutant dispersion. The effect of wind velocity distribution is modeled as a three-dimensional finite-impulse response (3D-FIR) filter. A phase space representation of the 3D-FIR filter window is discussed. The resulting pollutant dispersion is the multiplication in the phase space of the 3-D Fourier transform of the pollutant concentration and the volume described by the filter window coefficients. The shape of the filter window in the phase space enables representing such effects as vortex shedding thermal currents, etc. The impact of spatial distribution of the sensors on the resulting pollutant spatial distribution and the 3-D FIR filter model employed also discuss. The case of a neutrally buoyant plume emitted from an elevated point source in a turbulent boundary layer considers. The results show that wind turbulence is an important factor in the pollutant dispersion and introduces expected random fluctuations in pollutant distribution and leads to spreading the distribution due to wind mixing.     

Assessment of heavy metals in the particulate matter of two Brazilian metropolitan areas by using <Emphasis Type="BoldItalic">Tillandsia usneoides</Emphasis> as atmospheric biomonitor

Purpose  

The aims of this paper were to quantify the heavy metals (HM) in the air of different sites in Rio de Janeiro (RJ) and Salvador (SA) using Tillandsia usneoides (Bromeliaceae) as a biomonitor, and to study the morphology and elemental composition of the air particulate matter (PM) retained on the Tillandsia surface.     

Dynamic Games in the Economics and Management of Pollution

The paper provides a survey of the literature which utilizes dynamic state-space games to formulate and analyze intertemporal, many decision-maker problems in the economics and management of pollution.     

Pesticide cocktails can interact synergistically on aquatic crustaceans

Background, aim and scope  

The ergosterol biosynthesis-inhibiting (EBI) fungicide prochloraz can enhance the effect of other pesticides in a range of animal species. Approximately 50% of the fungicides used in Denmark are EBI fungicides. Hence, if they all have synergising potential, a risk assessment of pesticide mixtures based on additivity might not suffice. This study investigates the synergising potential of six different EBI fungicides representing the imidazoles (prochloraz), the triazoles (epoxiconazole, propiconazole and tebuconazole), the piperidines (fenpropidin) and the morpholines (fenpropimorph) together with the pyrethroid insecticide alpha-cypermethrin.     

Assessing of Environmental Quality in Six Areas in India,Sri Lanka and Bangladesh

Environmental quality for environmental health has been examined visually by describing general conditions and drinking water supply, sanitation and solid waste treatment conditions and practices in six South-East Asian villages with a dense population. The environmental review was supplemented by discussions with local people and political and administrative decision makers. Some drinking water analyses were done in order to show the water quality to the local people. The quality of the general conditions and the conditions and practices of drinking water supply, excreta disposal and solid waste treatment practices have been graded with the grading system presented below. The grading could be done in 1 or 2 days in each area by two persons, of which one was an environmental scientist and the other a social scientist, who also knew the local culture and worked as a translator.     

Digit ratios (2D:4D), secondary sexual characters and cell-mediated immunity in house sparrows <Emphasis Type="Italic">Passer domesticus</Emphasis>

Homeobox genes regulate development of digits, and it has been suggested that the ratio of length of second to length of fourth digit reflects such genetic effects in a sex-specific manner. We show that digit ratios in the sexually dichromatic house sparrow Passer domesticus differ between sexes, with males having higher ratios than females, and that individuals produce consistent ratios on the two feet. If Homeobox or other genes had pleiotropic effects on development of digits, behavior, and physiology of males and females, we would expect secondary sexual characters and immunity to be related to digit ratio in a sex-specific manner. The size of the visible part of the black badge in February (a secondary sexual character), but not total badge size, was positively correlated with digit ratios, suggesting that males with more male-like digit ratios had larger visible badges. Because of sex-specific effects of development on secondary sexual characters and immunity, we predicted sex-specific differences in immune response to be related to digit ratio. House sparrows with large digit ratios had weaker T cell-mediated immune response than individuals with small digit ratios, particularly in females, implying that females with more male-like digit ratios had weak immune responses. These findings are consistent with the hypothesis that early development, as reflected by digit ratios, and genetics affect the expression of adult characters that are supposedly strongly contributing to fitness.     

Orientation and navigation in bats: known unknowns or unknown unknowns?

Bats have been extensively studied with regard to their ability to orient, navigate and hunt prey by means of echolocation, but almost nothing is known about how they orient and navigate in situations such as migration and homing outside the range of their echolocation system. As volant animals, bats face many of the same problems and challenges as birds. Migrating bats must relocate summer and winter home ranges over distances as far as 2,000 km. Foraging bats must be able to relocate their home roost if they range beyond a familiar area, and indeed circumstantial evidence suggests that these animals can home from more than 600 km. However, an extensive research program on homing and navigation in bats halted in the early 1970s. The field of bird navigation has advanced greatly since that time and many of the mechanisms that birds are known to use for navigation were not known or widely accepted at this time. In this paper I discuss what is known about orientation and navigation in bats and use bird navigation as a model for future research in bat navigation. Technology is advancing such that previous difficulties in studying orientation in bats in the field can be overcome and so that the mechanisms of navigation in this highly mobile animal can finally be elucidated.     

Ephemeral spawning aggregations in the Mediterranean sardine, <Emphasis Type="Italic">Sardina pilchardus</Emphasis>: a comparison with other multiple-spawning clupeoids

Using previously published histological data on multiple, monthly samples of Sardina pilchardus collected in the central Aegean and Ionian Seas (September 1999–August 2000, and November 2000–February 2001), the Mediterranean sardine was treated as a case study to investigate the biological characteristics of ephemeral spawning aggregations in multiple-spawning clupeoids. Actively spawning (Day₀) females in the Mediterranean sardine, i.e., the daily class of spawners caught a few hours prior, during, or after the spawning act, were shown to separate spatially from late (Day₁₊) spawners and non-spawning females, taking with them a large proportion of conspecific males which were also in advanced spawning condition and in better somatic condition compared to the remaining population. In addition, information from 28 stocks of multiple-spawning clupeoids from a wide range of geographic locations, belonging to 14 species and 2 families (Engraulidae and Clupeidae), was reviewed and analyzed pertinent to the formation of ephemeral spawning aggregations. Results from the latter analysis indicated similar patterns of spatial segregation of Day₀ spawners in the reviewed clupeoid stocks as in the Mediterranean Sardine, which strongly suggested that the formation of ephemeral spawning aggregations is a common behavioral trait among multiple-spawning clupeoids. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.