The effect of climate on nest orientation in the Rufous Hornero Furnarius rufus

ABSTRACT

Capsule: Within breeding season changes in nest orientation of the Rufous Hornero Furnarius rufus may reflect responses to the local climate.

Aims: To explore the effect of climate on the orientation of closed-cup nests of the Rufous Hornero at a subtropical urban site throughout its breeding period.

Methods: The breeding season was divided into two periods: a cold period with low rainfall and a warm, humid period. For each period, the mean nest entrance orientation and distribution were estimated and compared against a random orientation model.

Results: A total of 42 nests were found during the first period of reproduction and 32 during the second period. In both cases, the mean orientation was non-random and significantly different between the two periods: nests were more likely to be orientated towards the northwest in the first period and to the east in the second period.

Conclusions: Climate variation throughout the breeding season was reflected in differences in nest entrance orientation. This could be because this species takes advantage of solar radiation to increase the temperature within the nest during the first cold months of the breeding season and reduces the humidity of the nest, generated by intense rain, as the season progresses.     

Non-random leaf orientation in Lactuca serriola L.

Abstract Leaf shapes and leaf orientation of Lactuca serriola serriola and serriola integrifolia were studied. Leaf shapes in L. serriola serriola differed greatly from those of L.serriola integrifolia, but leaf surface areas were similar. In exposed habitats, leaf orientation of cauline leaves of both forms was non-random, with leaves almost vertical and tending to orient with their lamina normal to the east and west. In the shade, cauline leaves oriented randomly. An experiment demonstrated that the orientation of leaves did not change significantly once they were fully expanded. The leaf orientation in L. serriola affected the diurnal distribution of solar irradiance intercepted by a leaf. Peak solar radiation fluxes are incident on the rosette leaves at midday, but on the cauline leaves the peak solar radiation flux occurs early in the morning and again late in the afternoon. The significance of this unusual leaf orientation is discussed in relation to water loss and carbon gain.     

Nestbox orientation: a species-specific influence on occupation and breeding success in woodland passerines

Capsule Nestbox orientation has species-specific influences on nestbox occupation and breeding success for woodland passerines.

Aims To determine if nestbox orientation had an influence upon nestbox selection or breeding success for three co-occurring woodland passerines.

Methods We analysed 15 consecutive years of breeding data (1990–2004) from 295 nestboxes in the UK using circular statistical analyses to examine the influence of orientation upon nestbox occupation and breeding success for three species, Blue Tit Cyanistes caeruleus, Great Tit Parus major and Pied Flycatcher Ficedula hypoleuca.

Results The three species used nestboxes of all orientations during the 15-year period. The frequency of nestbox occupation by Great Tits correlated with orientation (the mean number of nests in boxes oriented south-southwest was lower than the mean number of nests in boxes facing other directions). There was no such relationship for Blue Tits or Pied Flycatchers. Nestbox orientation influenced the breeding success of Pied Flycatcher (the mean number of young to fledge from boxes oriented south-southwest was lower than from boxes facing other directions). There was no such relationship for Blue or Great Tits.

Conclusion Nestbox orientation can be an important influence on occupation and breeding success, but this differed between species. Intriguingly, although the directionality reduced nestbox occupation (Great Tit) and breeding success (Pied Flycatcher) was the same (south-southwest), there was a disparity in the influence of orientation for Great Tit (orientation influenced the frequency of occupation but not success) and Pied Flycatcher (orientation did not influence occupation but did affect success). We discuss these disparities, considering the possible influences of mating strategy, breeding phenology, nestbox microclimate and offspring quality.     

Motility and gravitactic orientation of the flagellate,Euglena gracilis,impaired by artificial and solar UV-B radiation

The effects of ultraviolet radiation on the gravitactic orientation of the freshwater flagellate,Euglena gracilis, were determined by a real time image analysis system. Both artificial UV radiation and solar radiation in a temperature-controlled growth chamber were employed. Histograms of gravitaxis showed that the degree of orientation decreased with increasing exposure time; this can be quantified using the Rayleigh test and upper quadrant summation. The effects of artificial UV radiation on the orientation are considerably stronger than those of solar radiation, probably because the radiation source emits higher fluence rates below 300 nm than found in solar radiation. The effects of monochromatic ultraviolet radiation on motility have been determined, and an action spectrum has been calculated.     

Nest orientation of the Spotted Barbtail, <Emphasis Type="Italic">Premnoplex brunnescens</Emphasis>, is strongly correlated with stream flow

The placement and orientation of bird nests may strongly influence reproductive success. For many species, nest orientation is related to the cardinal directions and has to do with prevailing winds or solar exposure. Nest orientation differs among species in different environments, variously cooling or warming nests to maintain a nest microclimate optimal for successful development of eggs and young. The Spotted Barbtail (Premnoplex brunnescens) builds mossy, enclosed nests along shaded streams in Neotropical cloud forests. It shows a unique pattern of nest orientation, whereby nests are oriented in relation to the direction of water flowing below the nest entrance, rather than compass bearing. Nests face in one of three directions in relation to the stream: downstream, upstream, or perpendicular to the flow of the water. I discuss the ability of various hypotheses to explain this pattern in the context of factors affecting nest orientation in other species. While the reasons for this pattern of orientation remain unclear, orientation is likely driven by the need to create and maintain an optimal internal nest microclimate.     

Predators and nest success of Sky Larks Alauda arvensis in large arable fields in the Czech Republic

Capsule Nest failure owing to a range of predators was high, but the level and specificity of nest depredation cannot be generalised.

Aims To determine fates and predators of Sky Lark nests in conventionally managed arable fields in the Czech Republic.

Methods Sky Lark nests in large fields (mainly Maize, Sugar Beet and Opium Poppy) were monitored by means of continuous video surveillance.

Results Primary nest fates of 42 active nests were fledging (13), depredation (22), desertion (5), nestling death (1), and flooding (1). The overall nest success (Mayfield estimate) was 17% (all mortality factors considered) or 27% (only depredation). Depredation events were caused by Marsh Harrier Circus aeruginosus (11), Hooded Crow Corvus cornix (4), Stone Marten Martes foina (3), Montagu’s Harrier Circus pygargus (2), Red Fox Vulpes vulpes (2), Hedgehog Erinaceus sp. (2) and Eurasian Jackdaw Corvus monedula (1). Successful nests were only slightly more away from field edge than depredated nests; nests taken by birds tended to be closer to field edge than those depredated by mammals. The possible reasons for the absence of a clear edge effect include comparatively large field parcels (about 50 ha) and location of nests far from field edge (median = 195 m).

Conclusion Nest survival and composition of nest predators are site‐specific and contingent upon the study method and may not be simply generalised.     

Modelling the nesting-habitat of the Cinereous Vulture Aegypius monachus on a fine scale for conservation purposes

Capsule Nests of Cinereous Vultures were found to be located farther from roads, villages and the edge of large vegetation patches. They preferred large vegetation patches containing extensive Cork Oak cover on steeper slopes and with lower solar radiation. Less than 8% of the study area was predicted to be suitable for nesting.

Aims To generate a predictive habitat suitability map for the Cinereous Vulture's nesting-habitat on a fine scale for conservation applications within its breeding range.

Methods Habitat features of 43 nest-locations and random points were compared in order to identify nest-habitat selected in the region of the Hornachuelos Natural Park (Spain). A logistic regression approach was used to create habitat models.

Results Compared with random points, nests were found to be located farther from roads, villages and patch edges, and in large vegetation patches containing extensive Cork Oak cover on steeper slopes with lower solar radiation. The predictive map revealed that less than 8% of the study area had a greater probability of occupancy than 0.8.

Conclusions Most habitats in the study area are unsuitable for nesting suggesting that conservation of the best suitable areas is important. The fine-scale predictive map approach may be valuable in designating conservation priority areas.     

Predators of Spotted Flycatcher Muscicapa striata nests in southern England as determined by digital nest-cameras

Capsule Avian predators are principally responsible.

Aims To document the fate of Spotted Flycatcher nests and to identify the species responsible for nest predation.

Methods During 2005–06, purpose-built, remote, digital nest-cameras were deployed at 65 out of 141 Spotted Flycatcher nests monitored in two study areas, one in south Devon and the second on the border of Bedfordshire and Cambridgeshire.

Results Of the 141 nests monitored, 90 were successful (non-camera nests, 49 out of 76 successful, camera nests, 41 out of 65). Fate was determined for 63 of the 65 nests monitored by camera, with 20 predation events documented, all of which occurred during daylight hours. Avian predators carried out 17 of the 20 predations, with the principal nest predator identified as Eurasian Jay Garrulus glandarius. The only mammal recorded predating nests was the Domestic Cat Felis catus, the study therefore providing no evidence that Grey Squirrels Sciurus carolinensis are an important predator of Spotted Flycatcher nests. There was no evidence of differences in nest survival rates at nests with and without cameras. Nest remains following predation events gave little clue as to the identity of the predator species responsible.

Conclusions Nest-cameras can be useful tools in the identification of nest predators, and may be deployed with no subsequent effect on nest survival. The majority of predation of Spotted Flycatcher nests in this study was by avian predators, principally the Jay. There was little evidence of predation by mammalian predators. Identification of specific nest predators enhances studies of breeding productivity and predation risk.     

Herbaceous ground cover reduces nest predation in olive groves

Capsule Bare ground increases artificial nest predation in olive groves.

Aims To assess the effect of different soil management regimes on nest predation rates in olive groves.

Methods We performed nest predation experiments with artificial nests during the breeding season in 2013, in two areas of southern Spain. Each artificial nest (n?=?300) contained three quail Coturnix eggs, two of which were unmanipulated and the third one was emptied and injected with plaster. Predators were identified by marks on eggs filled with plaster.

Results Ground nests were significantly more depredated, irrespective of the presence of ground cover; tree nests were less depredated in fields with ground cover. There was a clear difference in nest predators of ground and tree nests. Rodents were the most frequent predators of tree nests.

Conclusion Lower predation rates of tree nests in orchards with ground cover are probably linked to a change in the foraging behaviour of rodents, which in these more complex habitats might be restricted by rodents' own risk of predation. This study underscores the important role of agricultural practices in preserving farmland bird communities, particularly tree-nesting species, suggesting that for this group, implementation of ground cover in olive groves might enhance breeding success by reducing nest predation rates.     

Mortality of Wood Warbler Phylloscopus sibilatrix nests in Welsh Oakwoods: predation rates and the identification of nest predators using miniature nest cameras

Capsule Predation was the main cause of nest failure, but predation rates have remained unchanged since the 1980s. Eurasian Jays Garrullus glandarius were the most common predator.

Aims To quantify, and compare, nest predation rates for 1982–84 and 2009–11, and to identify predators of Wood Warbler Phylloscopus sibilatrix nests in Welsh oakwoods.

Methods During 2009–11, 167 Wood Warbler nests were monitored and purpose-built miniature nest cameras deployed at 73 of them. Nest predation rates were compared with 67 nests monitored during 1982–84.

Results Of 167 nests monitored from 2009 to 2011, 62 failed due to predation (32/73 camera nests, 30/94 non-camera nests), giving an overall Daily Survival Rate (DSR?±?se) of 0.979?±?0.003. This was not significantly different from the rate during 1982–84 (0.967?±?0.006). In 2009–11, the DSR of nests declined temporally during the season at both the egg and chick stages. For chick stage nests, DSR varied annually and nonlinearly with age of nestlings. There was no evidence for an effect of cameras at either stage. Of 32 camera nests lost to predation, the predator was identified from 28, resulting in 30 predators being identified. There was one case of multiple predators at a single nest. The majority of nest predation was carried out by birds (28/30), predominantly Eurasian Jays (18/28), but also Common Buzzards Buteo buteo (5/28), Great Spotted Woodpeckers Dendrocopos major (3/28) and Eurasian Sparrowhawks Accipiter nisus (2/28). There was one predation by both a Eurasian Badger Meles meles and a Red Fox Vulpes vulpes. There were no records of Grey Squirrels Sciurus carolinensis depredating nests.

Conclusions Nest predation rates were similar in both periods, suggesting that increased rates of nest predation have not been driving the decline of the Wood Warbler population in Wales. Deployment of nest cameras did not affect nest survival rates and were successful in identifying nest predators, the majority of which were avian, especially Eurasian Jays. Knowledge of the identity of nest predators can aid the development of conservation measures.     

Nest-site selection and nest size influence the incubation temperature of Morelet's crocodiles

In oviparous tetrapods, the nesting-site selection by females is related to the habitat characteristics, which influences nest incubation temperature. Females can directly influence the incubation temperature by choosing certain construction materials or by building nests of different sizes. There are few studies focusing on these aspects in crocodilians that build mound nests. The aim of this study was to determine whether the nest size, its exposure to solar radiation, and the environmental temperature influence the incubation temperature of Morelet's crocodile (Crocodylus moreletii) nests. Artificial nests of two sizes (small and large) were constructed with similar characteristics to natural nests and placed in two locations differing in exposure to solar radiation (shaded and sunny). We used temperature and relative humidity data loggers to record the incubation temperature inside each nest every hour during the species' natural nesting period. Likewise, we recorded the ambient temperature every hour where the experiments were set up with temperature data loggers. We found that nest size and its exposure to solar radiation affected the incubation temperature, with smaller nests in shaded locations having lower incubation temperatures than larger nests in sunny locations. We discuss the importance of nest-site selection and maintenance behaviour of the mound nest by female crocodiles on the incubation temperature of the nest.     

Effect of nest-site microclimatic conditions on nesting success in the Lesser Kestrel Falco naumanni

Capsule: Microclimatic conditions in the nests of the Lesser Kestrel Falco naumanni, particularly the percentage of time of extremely low humidity, affect breeding success.

Aim: To study the effect of within-nest temperature and humidity on nest productivity, and the correlation between nest productivity and the order of dates on which nests were occupied by the parents. To compare microclimatic conditions in the nest, breeding success and order of occupation between nests under tile roofs and in artificial nest boxes.

Methods: Three different Lesser Kestrel colonies were monitored in Israel – one rural, one urban and one in an open country habitat. Data loggers were placed in 39 nests for the entire breeding period to measure temperature and humidity. The number of fledglings was recorded for each nest, as well as the date of occupation.

Results: Full microclimatic data from 35 nests suggest that percentage of time of extremely low humidity is the major predictor of nest productivity – low humidity is negatively correlated with nest productivity. Sites of more successful nests were occupied earlier. Considering only successful nests, the urban colony had the lowest breeding success of the three colonies. There was no significant difference in mean productivity between nests in roofs and nest boxes, but nests in roofs were occupied earlier.

Conclusion: Nest microclimate, particularly low humidity, affects nesting success in addition to colony location.     

The study of nest-site preferences in Eleonora’s falcon Falco eleonorae through digital terrain models on a western Mediterranean island

This study addresses nesting-site preferences in Eleonora’s falcon Falco eleonorae by means of geographic information systems and high-quality high-resolution digital terrain models (DTMs). A small western Mediterranean archipelago (Columbretes Islands) with a colony of 34 pairs was chosen as a case study. Overall, 21 grid variables obtained from DTM were considered of which 12 showed a significant effect. Four of them were topographic (i.e. elevation, X-axis aspect, slope and curvature), four climatic (i.e. wind exposure, solar insolation, solar radiation and radiation index), three anthropogne (visibility of lighthouse beam, visibility of antropic zones and distance to antropic zones) and one biotic (vegetation cover). Falcon nests were placed on pixel cells with lower average insolation and radiation than cells without nests, but had higher values of wind exposure. Nests were built on concave sites mainly with an easterly facing aspect and steep slopes. Falcons were shown to respond to human presence as all antropic variables considered had a significant effect. The results have a number of management and conservation implications, because the knowledge of nesting preferences of the species allows the proper design of sanctuaries and an appropriate human use of these areas.     

Nest survival of Woodpigeons (Columba palumbus) in North African forests

Capsule The nesting success of the Woodpigeon Columba palumbus in oak forests in Morocco is affected by human disturbance and nest-site characteristics.

Aims To determine factors affecting the nesting success of Woodpigeons subject to two levels of disturbance in a holm oak Middle Atlas forest.

Methods Woodpigeon nests were monitored in highly disturbed (n?=?30) and less-disturbed sites (n?=?60) over two years (2010–11). Logistic-exposure models were used to estimate daily nest-survival rate and evaluate mechanisms (altitude, temporal factors, nest location, nest-site habitat and degree of human influence) affecting nest survival.

Results Daily nest-survival rate was higher in less-disturbed sites (0.987; 95% CL: 0.980–0.991) than in high-disturbance sites (0.967; 95% CL: 0.949–0.978). Increasing density of trees surrounding nest sites and distance from the nest tree to the closest track increased daily nest-survival rate.

Conclusions Less-disturbed sites confer better nesting conditions than highly disturbed ones. Management measures should control the access of vehicles, especially trucks, in the forest of the Middle Atlas and introduce a grazing regime that will allow the forest regeneration, which would improve Woodpigeon nesting success by increasing the density of holm oak trees.     

Radiation exposure in supersonic transport by solar flares

Summary The following discourse presents the result of a theoretical analysis of the radiation exposure for solar proton beams and their secondaries in the altitude region of SST (supersonic transport) and pole regions. A statistical analysis of forms and intensities of measured solar flares has been made. The radiation dosage is calculated as a function of atmospheric depth for several characteristic flares. The dosage in rems from secondary neutrons exceeds the dosage in rems from protons in the altitude region of SST for flare events with low characteristic slopeparameterG, In general the radiation is — without some rare extreme events — beyond of dangerous limits and the rare extreme exposure values will be of some hundred mrem/h.     

Nest site selection by a neotropical swarm-founding wasp: seasonal alternation of nest orientation

Nest orientation in social insects has been intensively studied in warmer and cooler climates, particularly in the northern hemisphere. Previous studies have consistently shown that species subjected to these climatic conditions prefer to select mostly southern locations where the nests can gain direct sunlight. However, very little is known on nest orientation in tropical and subtropical social insects. We studied nest orientations initiated by swarms throughout a year in a Brazilian swarm-founding wasp, Polybia paulista von Ihering (Hymenoptera: Polistinae). Swarms selected various orientations as nest sites, but there was a particular trend in that swarms in the winter period (May–August) preferred to build northward-facing nests. This preference is opposite from that of social wasps observed in the northern hemisphere. Colonies of this species can potentially last for many years with continuous nesting, but nesting activities of colonies during the winter are severely limited due to cool temperature and a shortened day length. Northward-facing nests are warmer through the gain of direct solar heat during the winter period; consequently, choosing northward-facing sites may be advantageous for swarms in terms of a shortened brood development and shortened time needed to increase metabolic rates during warm-up for flight.     

Nest orientation and hatching success in the tree pipit Anthus trivialis

Many open-nesting bird species orient their nests relative to surrounding vegetation to avoid adverse environmental conditions. In eastern England, tree pipit Anthus trivialis nests predominantly faced east, an orientation that provided shelter from prevailing WSW winds, allowed warming by the morning sun and which, together with relatively high field layer cover, shaded nest contents from the midday sun. Mean orientation moved from south to north through the breeding season as temperatures increased, suggesting that solar radiation was a key influence on nest placement for tree pipits in the study area. Tree pipit nests with eastward orientations experienced better hatching success than those in less-preferred orientations and it is suggested that this was due to their thermal advantages. In contrast, nest orientation had no influence on nestling survival.     

Effects of Solar Radiation on Photoorientation,Motility and Pigmentation in a Freshwater Cryptomonas

The effects of solar radiation on motility, photoorientation and pigmentation have been studied in a freshwater Cryptomonas species. The diaphototactic orientation performed by the cells is impaired within about 90 min of solar radiation. Likewise, the percentage of motile cells within the population and the average velocity of the swimming cells decreases within about the same exposure time. This effect is not due to a thermal stress but rather seems to be caused by the solar UV-B component, since decreasing short wavelength UV radiation by means of an artificial ozone filter or UV cut-off filters increased the tolerated exposure time. Solar radiation also bleached the photosynthetic pigments of the cells as shown by absorption difference spectra.     

Different nest predator guild associated with egg size in the Patagonian temperate forest

Capsule: Studies of nest predation using artificial nests need to consider the effect of egg size on the types of predator that are detected.

Aims: To estimate the nest predation rate in the Patagonian temperate forest and evaluate the influence of egg size on predator guild.

Methods: On different plant species, we placed 108 nests each containing eggs of either Atlantic Canary Serinus canaria or Common Quail Coturnix coturnix, and a model clay egg of equal size to the real egg. Nest predators were identified from the marks left on the clay eggs or by videos recorded using camera traps.

Results: 86% of the nests were predated. Birds, mainly Chimango Caracara Milvago chimango, were the main nest predators. A marsupial, the Monito del Monte Dromiciops gliroides, and rodents also contributed to nest predation. Nest predation rates were similar for both egg sizes but the nest predator guild was different. Birds and rodents preyed on both eggs but the Monito del Monte consumed mainly small eggs.

Conclusion: Egg size did not influence the rate of nest predation but, instead, affected the nest predator guild. Consequently, in order to avoid underestimating the impacts of small predators, egg size should be considered in studies of nest predation.     

Growth rate and basal area response curves of four Eucalyptus species on Mt. Wellington,Tasmania

Abstract. The heights, diameters and regrowth basal areas of 22-yr old fire-initiated regeneration of Eucalyptus delegatensis ssp. tasmaniensis, E. urnigera, E. coccifera and E. johnstonii were measured over altitudinal, solar radiation and drainage gradients on Mt. Wellington, Tasmania. The growth rate responses to the altitude gradient-complex vary from linear to curved depending on the performance measure, the species and the gradient. Much of the variation in growth rate appears to be a direct response to the physical environment. However, disparities between trends in growth rate and trends in re-growth basal area are consistent with the hypothesis that competition (sensu Grime 1979) is more important in productive environments and less important in stressful environments. A glasshouse trial with Eucalyptus seedlings indicated that potential growth rates decline with increasing altitude of seed source.