The ontogeny of bumblebee flight trajectories: From naïve explorers to experienced foragers

Understanding strategies used by animals to explore their landscape is essential to predict how they exploit patchy resources, and consequently how they are likely to respond to changes in resource distribution. Social bees provide a good model for this and, whilst there are published descriptions of their behaviour on initial learning flights close to the colony, it is still unclear how bees find floral resources over hundreds of metres and how these flights become directed foraging trips. We investigated the spatial ecology of exploration by radar tracking bumblebees, and comparing the flight trajectories of bees with differing experience. The bees left the colony within a day or two of eclosion and flew in complex loops of ever-increasing size around the colony, exhibiting Lévy-flight characteristics constituting an optimal searching strategy. This mathematical pattern can be used to predict how animals exploring individually might exploit a patchy landscape. The bees’ groundspeed, maximum displacement from the nest and total distance travelled on a trip increased significantly with experience. More experienced bees flew direct paths, predominantly flying upwind on their outward trips although forage was available in all directions. The flights differed from those of naïve honeybees: they occurred at an earlier age, showed more complex looping, and resulted in earlier returns of pollen to the colony. In summary bumblebees learn to find home and food rapidly, though phases of orientation, learning and searching were not easily separable, suggesting some multi-tasking

The Effects of Landscape and Experience on the Navigation and Foraging Behaviour of Bumblebees, Bombus terrestris

Bumblebees live in an environment where the spatial distribution of foraging resources is always changing. In order to keep track of such changes, bumblebees employ a variety of different navigation and foraging strategies. Although a substantial amount of research has investigated the different navigation and foraging behaviours of bumblebees, much less is known of the effects that landscape features have on bumblebee behaviour. In this thesis, a series of experiments were conducted in order to investigate the role that landscape features have on the navigation and foraging behaviour of Bombus terrestris and whether individuals’ experience influences such behaviour. A hedgerow situated next to the colony was not found to significantly shape the flight paths or foraging choices of naïve bumblebees. Homing success was investigated and used as a proxy for foraging range in different environment types. Both the release distance and the type of environment were found to have a significant effect on the homing success of Bombus terrestris workers. Previous experience of the landscape was also found to significantly affect the time it took bumblebees to return to the colony (homing duration) as well as the likelihood of staying out overnight before returning to the colony. When focusing on the first five flights of a naïve bumblebee worker, experience was not found to significantly affect flight duration. Experience, however, significantly affected the weight of pollen foraged. The observed behaviour of bumblebee gynes provisioning their maternal colony with pollen was also investigated. The influx of pollen into the colony was found to affect this behaviour, suggesting that gynes will provision the maternal colony in response to its nutritional needs. The overall results are also discussed within the context of informing landscape management practices. The results presented in this thesis point to the critical role that factors such as the physical landscape and individual experience play in influencing bumblebee behaviour.South Devon Area of Outstanding Natural Beauty (AONB) Uni

Navigation, recruitment, foraging ecology and visual systems of the banded sugar ant, camponotus consobrinus

Each species inhabits a unique niche. These niches can be defined by biotic or abiotic factors and animals evolve adaptations and behaviours to successfully exploit their niche. In this study I explore the niche of the Banded Sugar Ant, Camponotus consobrinus. I characterise the daily activity of this species that forages along the branches of Eucalyptus trees, a complex 3D environment. This species is crepuscular/nocturnal thus exposed to both dim and bright ambient light conditions, and appears to time outbound foraging activity to sunset throughout the year, although much less rigidly coupled compared to previously studied sympatric Myrmecia pyriformis. Activity onset occurs as a burst in outbound foragers during sunset and twilight periods, with few individuals returning to and leaving the nest during the night. Most individuals return to the nest in the morning, as sunrise approaches. I conducted temperature tolerance experiments with the aim of testing whether temperature might be an additional factor affecting the activity onset in this species. Through displacement experiments I show that both inbound and outbound foragers exclusively attend to landmark information for navigation and my experiments demonstrate for the first time a species of ant that does not rely on path integration for navigation or a celestial compass. Interestingly, however, the search patterns of displaced foragers do clearly involve path integration. Camponotus consobrinus recruits by tandem running where a recruit closely follows a leader. I characterise this behaviour and show by displacing recruits that they attend to landmark information for navigation, as well as that recruited individuals can also be experienced foragers. Further, I document dynamically changing tandem pairs, that is, apparently solitary foragers joining a tandem leader if her previous recruit has lost contact. Lastly, I examine the functional anatomy of the apposition compound eyes of C. consobrinus with the aim of identifying adaptations that allow these ants to operate at extremely varying light levels. C. consobrinus possess large diameter rhabdoms (7.32um) typical of night-active hymenoptera, but comparatively small facet lenses (20.81 - 25.56um). Light flux to the rhabdom is controlled by a variable primary pigment cell pupil that narrows the light path to less than 1um diameter at high light intensities. I further present initial findings of newly emerged ants that show an almost complete lack of screening pigment granules in both pigment and retinular cells C. consobrinus possess an unusually prominent dorsal rim area (DRA) with very large modified, non-twisting rhabdoms that are very likely to be polarization sensitive. However, I could not find evidence for the use of a polarization compass in this species. The results of experiments in which I occluded the DRA or the rest of the compound eye indicate that the DRA may mediate canopy orientation. I discuss C. consobrinus activity patterns, navigational mechanisms, compound eye adaptations and their recruitment strategy in the light of their association with foraging trees, the navigational information content of their environment and possible reasons for the particular temporal niche in which these ants are active

The Victorian Naturalist

v.116 (1999

Active sampling and decision making in Drosophila chemotaxis

The ability to respond to chemical stimuli is fundamental to the survival of motile organisms, but the strategies underlying odour tracking remain poorly understood. Here we show that chemotaxis in Drosophila melanogaster larvae is an active sampling process analogous to sniffing in vertebrates. Combining computer-vision algorithms with reconstructed olfactory environments, we establish that larvae orient in odour gradients through a sequential organization of stereotypical behaviours, including runs, stops, lateral head casts and directed turns. Negative gradients, integrated during runs, control the timing of turns. Positive gradients detected through high-amplitude head casts determine the direction of individual turns. By genetically manipulating the peripheral olfactory circuit, we examine how orientation adapts to losses and gains of function in olfactory input. Our findings suggest that larval chemotaxis represents an intermediate navigation strategy between the biased random walks of Escherichia Coli and the stereo-olfaction observed in rats and humans

Instructor field manual for Camp Highland Outdoor Science School

This project was designed to help instructors at Camp Highland Outdoor Science School in Cherry Valley, California. The camp is drsinged for fifth and sixth grade students. The manual would be a useful tool for instructors to reference information to assist in lession planning and activities. It would familiarize them with the local natual history in the area including geology, climate, plants and Native Americans

THE ECOLOGY OF FERAL CATS, FELIS CATUS, IN OPEN FOREST IN NEW SOUTH WALES: INTERACTIONS WITH FOOD RESOURCES AND FOXES

ABSTRACT Despite increasing evidence for the impact of feral cats Felis catus on native fauna in Australia, little is known of the ecology of cats, particularly factors that limit cat abundance. The ecology of the feral cat in Australia is represented by just 15 published studies on diet, only one of which has examined diet in relation to prey availability, and one study of home range behaviour. The red fox Vulpes vulpes is a significant pest to agriculture and native fauna in Australia and widespread fox removals have been proposed by the Vertebrate Biocontrol Cooperative Research Centre (VBCRC). However, there is concern that feral cats may increase compensatorily when fox populations are reduced, as has occurred in Western Australia, and therefore that predation pressure may not be alleviated on native fauna following fox control programs. This thesis is divided into two parts. First, the diet and home range size of cats is examined in relation to prey availability, and home range overlap and habitat use are determined. In the second part, several niche parameters (diet, home range and habitat use) that were potentially important resources for foxes and cats were quantified to assess the potential for competition. Avoidance and aggression between cats and foxes was examined using simultaneous radiotracking techniques and video observations. The hypothesis that foxes limit cats through interspecific competition (exploitation and interference) was then tested using a fox removal experiment. Finally, three further hypotheses were tested using a fox removal experiment to determine which factors limit feral cats at Burrendong. The four hypotheses tested were thus: i) Cats are limited independently of foxes through other factors such as food availability; ii) Foxes limit cats through interspecific competition (exploitation and/or interference); iii) Foxes limit cats through intraguild predation; iv) Cats benefit from the presence of foxes through facilitation. The diets and spatial use of feral cats were examined on agricultural land on the eastern shore of Lake Burrendong, New South Wales (32o40�S, 149o 10�E) between July 1994 and June 1997. The major land use for the area is water catchment under the agistment of sheep Ovis aries and cattle Bos taurus. The study area encompasses about 90 km2 of hilly terrain with undulating slopes that extend down to a flat foreshore area that has been extensively cleared of trees for grazing. The slopes are generally well timbered and dominated by white box Eucalyptus albens woodlands with some yellow box E. melliodora associations. Stands of cyprus pines Callitris spp. are also common. Feral cats and red foxes are established throughout the study area, and the European rabbit Oryctolagus cuniculus was abundant until the arrival of Rabbit Calicivirus Disease (RCD) in June 1996. The diet of feral cats was determined from the analysis of 499 scats. Rabbits were the staple prey of cats, with occurrence (O) in 81.6% of scats and comprising 68.4% by volume (V). Carrion (mostly eastern grey kangaroo Macropus giganteus and sheep) (O 21.5%, V 11.5%) was an important secondary food, particularly in winter and spring. Other mammalian prey included brushtail possums Trichosurus vulpecula (O 4.6%, V 2.4%), house mice Mus domesticus (O 6.2%, V 3.2%), black rats Rattus rattus (O 2.6%, V 1.4%) and a dunnart Sminthopsis sp. (probably S. murina) (O 0.2%, V 0.006%). Invertebrates (mostly Orthopterans) (O 41.5%, V 7.5%), vegetation (O 26.3%, V 3.6%), birds (O 4.2%, V 0.8%) and reptiles (O 3.4%, V 0.3%) were generally of minor importance in the diet. Few significant seasonal differences were found, although invertebrates contributed significantly less, and possums more, to the mean scat volume in winter and summer respectively. A significant dietary response was found for changes in rabbit abundance, but not for the other prey groups. Cats continued to prey heavily on rabbits after the arrival of Rabbit Calicivirus Disease, despite the relatively low numbers of rabbits. Ten months post-RCD, house mice increased in importance in the diet. However, it was not known whether this represented prey switching sensu stricto or opportunistic predation on an increased mouse population, as mouse abundance was not measured during this period. Seventy-seven cats (48 recaptures) were caught in 6762 trap nights between November 1994 and August 1996 using both cage traps and leg-hold traps. A further 18 individual cats were trapped as non-target animals by the VBCRC Fox Sterility Project and used in this study. Trapped adult cats were fitted with radio collars and their home range size, overlap and habitat use examined. Home ranges and core areas were quantified using 95% and 50% kernel utilisation distributions (KE 95 and KE 50) and minimum convex polygons (MCP 100, MCP 95, MCP 50). Four habitat types (grassland, open woodland, open forest, and mudflats) were delineated on aerial photographs and a habitat map produced using ARC/INFO. Compositional analysis was used to examine habitat preference in cats. Home range sizes of cats (n = 15, 598 fixes) in winter 1995, prior to fox removal, were similar to those reported in the only published study of cat spatial use in Australia, but larger than those recorded elsewhere. This may have reflected more dispersed food resources in Australia, although home range size was not correlated significantly with rabbit abundance. Male ranges (MCP 95 = 284 ha, n = 11) tended to be larger than females ( = 151ha, n = 4), but no differences were detected between young (1-3 years, = 271ha, n = 7) and old (>3 years, = 221ha, n = 8) cats. Cats were active both by day and night with no temporal differences being detected in range size. Both adult male and female cats tended to be solitary, although home ranges overlapped extensively. Kin groups were indicated (but not confirmed) as most inter-sexual overlap occurred between young and old cats. Habitat composition of home ranges generally reflected the availability of habitats at the study site, although cats significantly avoided mudflats. Home ranges comprised mostly open woodland and open forest habitats with smaller areas of grassland and mudflats. However, within individual home ranges, cats used grassland and open woodland habitats most often where rabbits were more abundant. Inter-individual (sex, age) or temporal (day/night) differences in habitat use were not detected. Comparison of resource use between cats and foxes indicated a large overlap in diet, home ranges and habitat use. Dietary breadths and overlaps between cats and foxes increased when rabbit availability declined in autumn and post-RCD. Dietary overlap was high overall (75%), although some resource partitioning was detected. Rabbits were more important in the diet of cats than foxes, particularly in summer, when foxes ate more grasshoppers. Carrion, invertebrates and vegetation were more important for foxes than for cats overall. Home ranges of both cats and foxes comprised mostly open woodland habitats followed by grassland, open forest and mudflats, which largely reflected their relative availabilities. However, within individual home ranges, cats showed a preference for grassland habitats. In addition, cats tended to deposit scats more often than foxes at rabbit warrens and at hollow log entrances, while foxes deposited scats more often than cats on sand plots, tracks and at dams. The large overlap in resource use between cats and foxes indicated a high potential for exploitation competition. Foxes may attempt to lessen competition by killing cats (interference competition). Three radiocollared cats were killed by foxes and aggression was observed toward cats. Home ranges overlapped extensively, but avoidance was indicated from the simultaneous radiotracking of both predators, as greater separations and lower overlaps in home ranges and core areas were recorded between species than within species. In addition, video observations suggested avoidance of carcasses by cats in the presence of foxes. The hypothesis that foxes limit feral cats through interspecific competition was then tested using a fox removal experiment. Foxes were reduced at two of the four sites from October 1995 using �1080� baiting and spotlight shooting by the VBCRC Predator-Prey project. Resource use and abundance of cats were compared before and after fox removal and between treated and untreated sites. Although no increase in cat abundance followed the removal of foxes, significant behavioural changes by cats strongly suggested interspecific competition operating via exploitation and interference. Exploitation competition was supported by the increased consumption of carrion by cats at the treated sites after fox removal, while support for interference competition came from the increased use of grassland habitats at night after fox removal. The direction of the resource shifts to more prey-rich habitats indicated asymmetry in the relationship between the two predator species. Although the null hypothesis of no limitation of cats by foxes could not be rejected, as no increase in cat abundance was recorded after fox removal, interspecific competition was considered to be the most likely mechanism limiting feral cats at Burrendong. Intraguild predation was not indicated as no cat remains were found in any of the 343 fox scats or 255 fox stomachs that were examined. In addition, minimal evidence was found for facilitation between cats and foxes, or for food limitation. The potential for foxes to limit cats, as shown in this study, indicates that cats need to be considered in future fox control operations. Integrated pest management, where foxes, cats and rabbits are controlled together, is strongly proposed if the objective is to safeguard native fauna in Australia. Further research is required to improve the effectiveness of current techniques for censusing cat populations, particularly in forested areas. This is essential for monitoring the effectiveness of control campaigns and quantifying factors that limit cat populations, and ultimately for effective protection of susceptible native fauna

Mariner IV Mission to Mars. Part I

This technical report is a series of individual papers documenting the Mariner-Mars project from its beginning in 1962 following the successful Mariner-Venus mission. Part I is pre-encounter data. It includes papers on the design, development, and testing of Mariner IV, as well as papers detailing methods of maintaining communication with and obtaining data from the spacecraft during flight, and expected results during encounter with Mars. Part 11, post-encounter data, to be published later, will consist of documentation of the events taking place during Mariner IV's encounter with Mars and thereafter. The Mariner-Mars mission, the culmination of an era of spacecraft development, has contributed much new technology to be used in future projects