Trends in closed nest entrance orientation of the Rufous Hornero Furnarius rufus along an altitudinal gradient in South America

ABSTRACT

The orientation of the nest entrances of 464 nests of the Rufous Hornero Furnarius rufus were explored in relation to vegetation cover along an altitudinal gradient in Argentina. There was no correlation between altitude and orientation for covered nests, since they were well protected from direct solar radiation, however, uncovered nests were orientated more towards the north with increasing altitude, probably to take advantage of warming solar radiation at colder, higher altitudes.     

The effect of nest size on stone-gathering behaviour in the chinstrap penguin

Stone-collecting behaviour was studied in a colony of chinstrap penguins (Pygoscelis antarctica), to explore the likely importance of nest size. We randomly categorised nests as control or experimental. All nests were weighed at the beginning of the incubation period. In the experimental nests we removed stones constituting 50% of their initial weight, while in the control nests all the stones were returned after weighing. All nests were weighed again either prior to or just after hatching to determine likely changes in their weight. The mean weight increase of experimental nests was significantly higher than the mean weight increase of control nests. Size represents a property of the nest which individuals continuously monitor throughout the incubation/brooding period, reacting to changes in it by appropriate changes in stone-collecting rate. Accepted: 8 February 1999     

The effect of human observers on the intensity of nest predation

Disused nests containing eggs from aviary birds were used to determine the effect of human observers on the intensity of nest predation. Nest predation was significantly higher for nests visited daily than for nests visited only at the end of a typical incubation period. Care should be taken by nest observers to minimise the number of visits to nests of ground-nesting birds. The average distance of nests from the edge of the supporting plant was greater for unsuccessful than successful nests, implying that the position of nests is an important factor affecting their survival. Predation rates on active nests of White-fronted Chats Ephthianura albifrons visited daily over the same period were similar to those of experimental nests, suggesting that 'artificial' nests may be a useful tool for studying nest predation.     

Collective control of nest climate parameters in bumblebee colonies

We examined two aspects of the social control of nest climate in bumblebee colonies: which parameters of nest climate bumblebees actively down-regulate by fanning and the dynamics of the colony response as colony size increased. Colonies of Bombus terrestris were exposed to an increase in carbon dioxide, temperature or relative humidity. We performed 70 temperature trials (six colonies), 58 CO₂ trials (four colonies) and four humidity trials (two colonies). An increase in CO₂ concentration and temperature elicited a fanning response whereas an increase in relative humidity did not. This is the first report of fanning in bumblebee colonies to control respiratory gases. The number of fanning bees increased with stimulus intensity. The colony response to a CO₂ concentration of 3.2% was comparable to the colony response to a temperature of 30°C. A marked fanning response occurred at 1.6% CO₂, a concentration never exceeded in a large field nest during a pilot measurement of 10 days. We investigated the colony response over a wide range of colony sizes (between 10 and 119 workers). The proportion of the total workforce invested by colonies in nest ventilation did not change significantly; thus, the number of fanning workers increased with colony size. Furthermore, as colony size increased, the dynamics of the colony response changed: colonies responded faster to perturbations of their environment when they were large (60 or more individuals) than when they were small. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Use of Vocal Fingerprinting for Specific Discrimination of Gray (Microcebus murinus) and Rufous Mouse Lemurs (Microcebus rufus)

Advertisement calls are often important noninvasive tools for discriminating cryptic species and for assessing specific diversity and speciation patterns in nature. We investigated the contribution of these calls to uncover specific diversity in nocturnal Malagasy lemurs. We compared sexual advertisement and predator advertisement calls of two mouse lemur species, western gray and eastern rufous mouse lemurs (Microcebus murinus and M. rufus, respectively) living in two contrasting habitats (dry deciduous vs. rain forest), and analyzed them statistically. Both species emitted several highly variable whistle calls in the context of predator-avoidance. Intrapopulation variation was high and overlapped interspecific variation. Sexual advertisement calls, given in the mating context, displayed a totally distinct, species-specific acoustic structure. Whereas gray mouse lemurs produced rapidly multifrequency modulated, long trill calls, rufous mouse lemurs gave slowly frequency-modulated short chirp calls. Our results suggest specific status for gray and rufous mouse lemurs and indicate the importance of predation and social needs in shaping vocal communication.     

The effect of biota on global climate

A model consisting of two blocks (equations) was proposed for the analytical study of the biosphere-climate system over great periods of time. The first equation describes the balance of carbon dioxide in the atmosphere and represents the biological block of the model. The second equation is the equation of the energy balance or the physical block of the system. The model is based on the most general conceptions of living matter and the evolution process. A possible interpretation of some events and phenomena in the earth history in terms of the model is given.     

The effect of temperature on the orientation of the translocation quadrivalent in barley

The effect of three temperatures on the orientation of the translocation quadrivalent was studied on four different translocation heterozygotes of barley. The alternate orientation decreased while temperature increased, and especially the frequency of discordant (elliptic) orientation increased. The proportion of alternate orientation was extremely low, in these four translocations, at high temperature. The four translocation heterozygotes differed significantly from one another at low and medium temperature. The proportion of configurations with alternate orientation was significantly lower in late MI in comparison with early MI. It is proposed that the change in the proportion of the translocation configuration with different orientations during MI is due to some relationship between the number of active centromeres and the number of the relevant chiasmata which oppose the force exerted by the poles. Accordingly, rings with concordant adjacent orientation will separate earlier than alternate, and elliptic quadrivalents with only two active centromeres will be the last to separate.     

The effect of nest aggregation on the reproductive behaviour of the peacock blenny Salaria pavo

The effect of nest aggregation in courtship behaviour was tested experimentally in an ecologically constrained, sex-role reversed population of the peacock blenny Salaria pavo . Mixed sex groups of eight males and eight females were tested in experimental tanks, containing eight potential nests either aggregated or dispersed. In the aggregated treatment, males spent more time inside their nests and monopolized other potential nests, causing a female-biased operational sex ratio (OSR). In the aggregated treatment, females also expressed more courtship behaviour. The results in general support the prediction that the aggregation of nests promotes male monopolization of potential nests, resulting in fewer nest-holding males and therefore a female-biased OSR that leads to the reversal of sex roles.     

The effect of ectoparasite nest load on the breeding biology of the Penduline Tit Remiz pendulinus

In this study we investigated the importance of ectoparasite load in the nest on the breed-ing system of the Penduline Tit Remiz pendulinus, examining the effect of mite abundance in the nest on mate choice, reproductive success and parental effort. The two most common ectoparasites were the Northern Fowl Mite Dermanyssus hirundinis and the Northern Feather Mite Ornithonyssus sylviarum. The results show that mite load is important in mate choice but has no adverse effect on reproductive success. The results also indicate that infestation level is related to the quality of the male (mask-width). Parental feeding rate was negatively related to mite load. This relationship indicated that Penduline Tits did not compensate for higher parasite loads by increasing feeding but rather reflected the con dition of the parent and its investment in self-maintenance behaviour.     

The effect of carbonic anhydrase inhibitors on secretion by the parotid and mandibular glands of red kangaroos Macropus rufus

Summary The effects of carbonic anhydrase inhibitors on secretion by macropodine parotid and mandibular glands were investigated using anaesthetized red kangaroos. In the parotid gland, acetazolamide (500 mol·l^-1) reduced a stable acetylcholine-evoked, half-maximal flow rate of 2.02±0.034 to 0.27±0.023 ml·min^-1 (87% reduction). Concurrently, salivary bicarbonate concentration and secretion fell (129.4±1.46 to 80.9±1.63 mmol·l^-1 and 264.8±7.96 to 22.3±2.30 mol·min^-1, respectively), phosphate and chloride concentrations rose (14.0±0.79 to 27.6±0.85 mmol·l^-1 and 5.6±0.25 to 27.5±1.32 mmol·l^-1, respectively), sodium concentration and osmolality were unaltered, and potassium concentration fell (8.8±0.33 to 6.4±0.29 mmol·l^-1). High-rate cholinergic stimulation during acetazolamide blockade was unable to increase salivary flow beyond 11±0.9% of that for equivalent unblocked control stimulation. However, superimposition of isoprenaline infusion on the acetylcholine stimulation caused a three-fold increase in the blocked flow rate. These treatments were accompanied by small increases in salivary phosphate and chloride concentrations but not bicarbonate concentration. Methazolamide infusion caused similar changes in parotid secretion. In the mandibular gland, acetazolamide infusion had no effect on salivary flow rate during either low- or high-level acetylcholine stimulation. Acetazolamide caused no alterrations in salivary electrolyte secretion at low flow rates, but curtailed the rise in bicarbonate concentration associated with high-level acetylcholine stimulation. Acetazolamide administration did not affect the increase in salivary flow rate associated with isoprenaline infusion, but did block the concomitant increase in bicarbonate concentration and secretion substantially. It was concluded that neither cholinergic nor adrenergic stimulation of mandibular fluid secretion depends on secretion of bicarbonate derived from catalysed hydration of CO₂, but a substantial proportion of the increase in bicarbonate secretion during isoprenaline administration, which is probably ductal in origin, is so dependent. In contrast to other salivary glands, including the ovine parotid, fluid secretion by the kangaroo parotid gland during cholinergic stimulation is largely dependent (about 90%) on secretion of bicarbonate derived from hydration of CO₂ catalysed by glandular carbonic anhydrase. Fluid secretion during adrenergic stimulation is not bicarbonate dependent.Abbreviations b.w. body weight - PAH p-aminohippurate - PCO₂ partial pressure carbon dioxide - PCO₂ partial pressure of oxygen     

The ability of climate envelope models to predict the effect of climate change on species distributions

Climate envelope models (CEMs) have been used to predict the distribution of species under current, past, and future climatic conditions by inferring a species' environmental requirements from localities where it is currently known to occur. CEMs can be evaluated for their ability to predict current species distributions but it is unclear whether models that are successful in predicting current distributions are equally successful in predicting distributions under different climates (i.e. different regions or time periods). We evaluated the ability of CEMs to predict species distributions under different climates by comparing their predictions with those obtained with a mechanistic model (MM). In an MM the distribution of a species is modeled based on knowledge of a species' physiology. The potential distributions of 100 plant species were modeled with an MM for current conditions, a past climate reconstruction (21 000 years before present) and a future climate projection (double preindustrial CO₂ conditions). Point localities extracted from the currently suitable area according to the MM were used to predict current, future, and past distributions with four CEMs covering a broad range of statistical approaches: Bioclim (percentile distributions), Domain (distance metric), GAM (general additive modeling), and Maxent (maximum entropy). Domain performed very poorly, strongly underestimating range sizes for past or future conditions. Maxent and GAM performed as well under current climates as under past and future climates. Bioclim slightly underestimated range sizes but the predicted ranges overlapped more with the ranges predicted with the MM than those predicted with GAM did. Ranges predicted with Maxent overlapped most with those produced with the MMs, but compared with the ranges predicted with GAM they were more variable and sometimes much too large. Our results suggest that some CEMs can indeed be used to predict species distributions under climate change, but individual modeling approaches should be validated for this purpose, and model choice could be made dependent on the purpose of a particular study.     

Seroprevalence of antibodies to Toxoplasma gondii in the Pennsylvania bobcat (Lynx rufus rufus)

From 2000 to 2002 bobcat blood samples were collected, in association with the Pennsylvania Game Commission, during the recently reactivated bobcat hunting and trapping season. Sex, age, and county/township data were recorded for each animal. Blood was tested for antibodies to Toxoplasma gondii using the modified agglutination test. In the 2-yr study, 131 bobcat samples were collected in 14 Pennsylvania counties and 109 (83%) of these had antibodies to T. gondii (titer>or=25). A two-way Chi-Square test (95% confidence interval) yielded no significance differences in antibody prevalence between males (83%) and females (88%) or adults (83%) and juveniles (77%). All 14 counties had at least one bobcat with antibodies to T. gondii.     

The effect of nest ectoparasites on parental provisioning in a north-African population of the Blue Tit Parus caeruleus

Bird nests are often heavily infested with several haematophagous ectoparasite species that drain energy and other essential resources needed for the development of the rapidly growing chicks. The nutritional requirements of altricial chicks can only be satisfied by the parents frequently bringing prey to the nest. In a 3-year study, we tested experimentally whether a parasite-induced change in the nutritional budgets of the chicks in an Algerian population of the Blue Tit, could be compensated by a response in parental food provisioning behaviour. We found that nestling body mass and size did not differ between heat-treated 'parasite-free' nests and heavily infested control nests. However, after controlling for potential confounding variables (laydate, clutch size, chick age, year), we found that broods of heavily infested control nests were more frequently visited and fed than broods that received antiparasite treatment. The results are discussed in the framework of theory related to behavioural responses of hosts to parasites.