Protecting the Privilege of Burning Sugarcane at Harvest

The South African sugar industry burns 90% of the crop at harvest while 10% is harvested green. The trend to burn cane at harvest has increased over the past twenty years, despite growing pressure from the public and environmental legislation. This paper explores the influence that public pressure and legislation are having on the practise of burning and examines the actions that the industry has implemented in order to protect the privilege of burning sugarcane at harvest. A communication model and case studies are used to illustrate the interaction between the sugar industry, government and public role players over cane burning. Communication has proved to be a key management tool that has had to be dynamic and on going in order to engage the various role players effectively. It is presumed that the advantages of burning outweigh those of trashing and it is for the nuisance rather than the health factor that the public want cane burning banned on farms adjacent to residential or tourist areas. The government, however, regards agricultural burning as a contributory factor to high air pollution levels during the winter months and expects these levels to be reduced. Will the public be able to force change to the current practice of burning cane at harvest in the South African sugar industry or will the steps taken by the industry provide adequate protection? Although favourable outcomes have been achieved, cane burning remains under pressure from the public and government.cane burning, communication, environment, legislation, Farm Management,

UBV photometry of close visual double stars using an area scanner

A computer-controlled area scanner designed for use on close visual double stars is described. Techniques used in making observations and in subsequent reduction of the data are given. Problems encountered are discussed. Magnitude differences and magnitudes and colours of components are given for 153 bright southern close visual doubles. Separations are given for some of the stars. Absolute magnitudes are calculated for the primaries by several methods. Individual stars are discussed where appropriate. The accuracy of the results is discussed. No significant systematic errors are evident in the results, but systematic errors are present in the results of other authors. Suggestions are made for the future use of conventional photometers, scanners and other techniques in the field of visual double star photometry and astrometry

Effects of landmark distance and stability on accuracy of reward relocation

This work was supported by the University of St Andrews, the University of Lethbridge and the Natural Sciences and Engineering Council of Canada.Although small-scale navigation is well studied in a wide range of species, much of what is known about landmark use by vertebrates is based on laboratory experiments. To investigate how vertebrates in the wild use landmarks, we trained wild male rufous hummingbirds to feed from a flower that was placed in a constant spatial relationship with two artificial landmarks. In the first experiment, the landmarks and flower were 0.25, 0.5 or 1 m apart and we always moved them 3–4 m after each visit by the bird. In the second experiment, the landmarks and flower were always 0.25 m apart and we moved them either 1 or 0.25 m between trials. In tests, in which we removed the flower, the hummingbirds stopped closer to the predicted flower location when the landmarks had been closer to the flower during training. However, while the distance that the birds stopped from the landmarks and predicted flower location was unaffected by the distance that the landmarks moved between trials, the birds directed their search nearer to the predicted direction of the flower, relative to the landmarks, when the landmarks and flower were more stable in the environment. In the field, then, landmarks alone were sufficient for the birds to determine the distance of a reward but not its direction.PostprintPostprintPeer reviewe

Discovery of magnetic fields in three He variable Bp stars with He and Si spots

It is essential for the understanding of stellar structure models of high mass stars to explain why constant stars, non-pulsating chemically peculiar hot Bp stars and pulsating stars co-exist in the slowly pulsating B stars and beta Cephei instability strips. We have conducted a search for magnetic fields in the four Bp stars HD55522, HD105382, HD131120, and HD138769 which previously have been wrongly identified as slowly pulsating B stars. A recent study of these stars using the Doppler Imaging technique revealed that the elements He and Si are inhomogeneously distributed on the stellar surface, causing the periodic variability. Using FORS1 in spectropolarimetric mode at the VLT, we have acquired circular polarisation spectra to test the presence of a magnetic field in these stars. A variable magnetic field is clearly detected in HD55522 and HD105382, but no evidence for the existence of a magnetic field was found in HD131120. The presence of a magnetic field in HD138769 is suggested by one measurement at 3 sigma level. We discuss the occurence of magnetic B stars among the confirmed pulsating B stars and find strong magnetic fields of order kG and oscillations to be mutually exclusive.Comment: 5 pages, 3 figures, 2 tables, accepted for publication in A

From a sequential pattern, temporal adjustments emerge in hummingbird traplining

Animals that feed from resources that are constant in space and that refill may benefit from repeating the order in which they visit locations. This is a behavior known as traplining, a spatial phenomenon. Hummingbirds, like other central‐place foragers, use short traplines when moving between several rewarding sites. Here we investigated whether traplining hummingbirds also use relevant temporal information when choosing which flowers to visit. Wild rufous hummingbirds that were allowed to visit 3 artificial flower patches in which flowers were refilled 20 min after they had been depleted repeated the order in which they visited the 3 patches. Although they tended to visit the first 2 patches sooner than 20 min, they visited the third patch at approximately 20‐min intervals. The time between visits to the patches increased across the experiment, suggesting that the birds learned to wait longer before visiting a patch. The birds appeared to couple the sequential pattern of a trapline with temporal regularity, to some degree. This suggests that there is a temporal component to the repeated spatial movements flown by foraging wild hummingbirds.PostprintPeer reviewe

The blue stragglers formed via mass transfer in old open clusters

In this paper, we present the simulations for the primordial blue stragglers in the old open cluster M67 based on detailed modelling of the evolutionary processes. The principal aim is to discuss the contribution of mass transfer between the components of close binaries to the blue straggler population in M67. First, we followed the evolution of a binary of 1.4M$_\odot$+0.9M$_\odot$. The synthetic evolutionary track of the binary system revealed that a primordial blue straggler had a long lifetime in the observed blue straggler region of color-magnitude diagram. Second, a grid of models for close binary systems experiencing mass exchange were computed from 1Gyr to 6Gyr in order to account for primordial blue-straggler formation in a time sequence. Based on such a grid, Monte-Carlo simulations were applied for the old open cluster M67. Adopting appropriate orbital parameters, 4 primordial blue stragglers were predicted by our simulations. This was consistent with the observational fact that only a few blue stragglers in M67 were binaries with short orbital periods. An upper boundary of the primordial blue stragglers in the color-magnitude diagram (CMD) was defined and could be used to distinguish blue stragglers that were not formed via mass exchange. Using the grid of binary models, the orbital periods of the primordial BSs could be predicted. Compared with the observations, it is clear that the mechanism discussed in this work alone cannot fully predict the blue straggler population in M67. There must be several other processes also involved in the formation of the observed blue stragglers in M67.Comment: 11 pages, 6 figures, A&A accepte

Wild rufous hummingbirds use local landmarks to return to rewarded locations

This work was supported by the University of St Andrews, the University of Lethbridge and the Natural Sciences and Engineering Council of Canada.Animals may remember an important location with reference to one or more visual landmarks. In the laboratory, birds and mammals often preferentially use landmarks near a goal (“local landmarks”) to return to that location at a later date. Although we know very little about how animals in the wild use landmarks to remember locations, mammals in the wild appear to prefer to use distant landmarks to return to rewarded locations. To examine what cues wild birds use when returning to a goal, we trained free-living hummingbirds to search for a reward at a location that was specified by three nearby visual landmarks. Following training we expanded the landmark array to test the extent that the birds relied on the local landmarks to return to the reward. During the test the hummingbirds' search was best explained by the birds having used the experimental landmarks to remember the reward location. How the birds used the landmarks was not clear and seemed to change over the course of each test. These wild hummingbirds, then, can learn locations in reference to nearby visual landmarks.PostprintPeer reviewe

Diel and Monthly Movement Rates by Migratory and Resident Female Pronghorn

Animal movement patterns are variable, with certain species primarily being diurnal and others nocturnal. Pronghorn (Antilocapra americana) are regarded as diurnal animals moving predominately during daylight hours. Anecdotal accounts, however, suggest that pronghorn move during the night but the extent, frequency, and importance of these nocturnal movement behaviors are unknown. To evaluate movements, we combined global positioning system relocation data from collared female pronghorn in the Northern Sagebrush Steppe between 2003 and 2007 with sunrise/sunset data within a geographical information system platform. We assessed whether mean and maximum movement rates were influenced by diel period (dawn, day, dusk, and night), month (January through December), movement strategy (migrant or resident), and year individuals were captured (2003, 2005, or 2006). Diel period and month greatly influenced mean and mean maximum movement rates. Pronghorn were indeed primarily diurnal in activity but significant movement did occur at night. Our results indicate pronghorn primarily move during the daytime, a period when humans also are most active on the landscape. This movement cycle has important implications for management and conservation of pronghorn at the northern periphery of its range

Why study cognition in the wild (and how to test it)?

An animal's behavior is affected by its cognitive abilities, which are, in turn, a consequence of the environment in which an animal has evolved and developed. Although behavioral ecologists have been studying animals in their natural environment for several decades, over much the same period animal cognition has been studied almost exclusively in the laboratory. Traditionally, the study of animal cognition has been based on well-established paradigms used to investigate well-defined cognitive processes. This allows identification of what animals can do, but may not, however, always reflect what animals actually do in the wild. As both ecologists and some psychologists increasingly try to explain behaviors observable only in wild animals, we review the different motivations and methodologies used to study cognition in the wild and identify some of the challenges that accompany the combination of a naturalistic approach together with typical psychological testing paradigms. We think that studying animal cognition in the wild is likely to be most productive when the questions addressed correspond to the species’ ecology and when laboratory cognitive tests are appropriately adapted for use in the field. Furthermore, recent methodological and technological advances will likely allow significant expansion of the species and questions that can be addressed in the wild.PostprintPostprintPeer reviewe

Numerical ordinality in a wild nectarivore

This work was supported by the Association for the Study of Animal Behaviour (S.D.H.), the University of Lethbridge, and the Natural Sciences and Engineering Research Council of Canada (RGPIN 121496-2003; T.A.H.)Ordinality is a numerical property that nectarivores may use to remember the specific order in which to visit a sequence of flowers, a foraging strategy also known as traplining. In this experiment, we tested whether wild, free-living rufous hummingbirds (Selasphorus rufus) could use ordinality to visit a rewarded flower. Birds were presented with a series of linear arrays of 10 artificial flowers; only one flower in each array was rewarded with sucrose solution. During training, birds learned to locate the correct flower independent of absolute spatial location. The birds' accuracy was independent of the rewarded ordinal position (1st, 2nd, 3rd or 4th), which suggests that they used an object-indexing mechanism of numerical processing, rather than a magnitude-based system. When distance cues between flowers were made irrelevant during test trials, birds could still locate the correct flower. The distribution of errors during both training and testing indicates that the birds may have used a so-called working up strategy to locate the correct ordinal position. These results provide the first demonstration of numerical ordinal abilities in a wild vertebrate and suggest that such abilities could be used during foraging in the wild.PostprintPeer reviewe