Master of Science - Science / Positive affective states guide the proximate performance of the appetitive and consummatory components of behaviours, such as foraging, that ultimately increase an animal’s fitness. Accordingly, promoting foraging in captive animals can enhance their welfare, defined as a predominance of positive (e.g. pleasure) over negative (e.g. stress) affective states. In three sets of experiments, I examined social foraging in two captive baboon troops housed at the Johannesburg Zoo, South Africa. I investigated (1) whether watching a demonstrator baboon forage cued conspecific observers to also forage; (2) how two factors known to influence the social transfer of foraging information and the motivation to forage (demonstrator status and hunger/satiation respectively) affected whether an animal was cued to forage upon watching a demonstrator forage; (3) the psychological mechanism through which this change in motivation to forage occurred; and (4) how socially-cued foraging behaviour could be incorporated into environmental enrichment protocols. I recorded the frequency of foraging for individual baboons and for each troop as a whole. I also scored the incidence of aggression in both troops. Upon watching a demonstrator forage from a monopolisable food source, observers increased their foraging efforts elsewhere in the enclosure. Demonstrator identity influenced the incidence of foraging by observers, with how well the demonstrator predicted food reward, rather than its status per se, determining observer foraging frequency. The psychological mechanism mediating the increase in foraging behaviour, as well as the effect of observer hunger/satiation on foraging, were unclear. The increased frequency of foraging by observers was accompanied by only a small rise in aggression. My data indicate that the use of social cues to motivate foraging behaviour could be employed to augment standard foraging enrichment protocols aimed at improving the welfare of captive animals.

I studied flock composition, distribution and foraging ecology of wintering wading birds along the Gulf of Mexico coast. I focused on geographic variability in wintering wading bird assemblages, the processes that structured these assemblages and habitat use by wading birds. I found considerable variation among three sites, Aransas National Wildlife Refuge (ANWR), Texas; Marsh Island Wildlife Refuge (MIWR), Louisiana; and Chassahowitzka National Wildlife Refuge (CNWR), Florida. Species comprising wintering wading bird assemblages varied regionally. ANWR had the most species-rich assemblage, with eight species. MIWR had only six wading bird species. And CNWR had only three different species. Processes that structured wintering wading bird assemblages also varied regionally. In ANWR, Texas, the Random Fraction niche apportionment model (RF model) best explained the empirical abundance data for ANWR. For abundance data from MIWR a good fit was obtained with the MacArthur Fraction (MF) model and the Power Fraction (PF) models. None of the models fully explained the CNWR abundance data. I also examined patterns of habitat partitioning among wintering wading birds at three different scales at two sites, Matagorda Island National Wildlife Refuge (MINWR) and Laguna Atascosa National Wildlife Refuge (LANWR). At the macrohabitat level, wintering wading birds showed interspecific differences in macrohabitat use of both open water habitats and vegetated flats. At the mesohabitat level all species at MINWR used the category nearest the edge most often, alternatively, at LANWR wading birds were most often in the mesohabitat category of 8.1- 12 m. from the edge. In both locations wading birds partitioned habitat based on water depth. Finally, I found that Great Egrets and Snowy Egrets participated more often in flock foraging and derived more benefits from feeding in flocks than other species. Great Egrets feeding in flocks had a higher mean strike rate than those foraging alone, whereas Snowy Egrets had a higher success rate foraging in flocks than those foraging alone. In the case of the darkercolored species (e.g., Great Blue Herons, etc.) they either showed no difference in behaviors between birds foraging in flocks versus those foraging alone or they actually did worse when they foraged in flocks.

No description available.

No description available.

No description available.

The aim of this study was to investigate the effects of changes in various environmental parameters on the underwater foraging behaviour of the American mink, Mustela vison. The study was conducted in an indoor pool. The effects of changes in the following parameters were investigated: (i) Water Depth. This was altered from 0.3 m to 1.65 m. (ii) Current Flow. Presence of either a deep or a surface current was compared to no current flowing. (iii) Prey Density. Four prey densities were used, 25%, 50%, 75% and 100%. (iv) Habitat Complexity. Hides were arranged in a regular, random or clumped pattern. The effects of habitat complexity were investigated in conjunction with prey density. Results are presented for gross changes in foraging behaviour, i.e. dive rate (number of dives per min), successful dive rate, hide visit dive rate, proportion of dives visiting a hide, proportion of successful dives and proportion of successful hide visits, and for finer changes within each dive, i.e. dive duration, time on bottom, number of hides visited per dive, mean time in hide, proportion of time on bottom spent hide searching, distance travelled underwater, proportion of direct to indirect dives, mean number of turns per dive, directionality of dives and revisiting of hides. The results showed that as depth increased, animals made fewer dives, but the dives were of longer duration. The extra time on bottom appeared to be used for locating hideswhich could no longer be located aerially before diving. Deep current was found to be not strong enough to seriously affect foraging behaviour. However, the surface disruption caused by the surface current, led to an increased dive rate, possibly in an attempt to locate hides that could no longer be located aerially, although other parameters such as proportion of dives visiting hides, dive duration etc., were generally unaffected by current flow. The conclusion was that mink were well able to continue foraging with current speeds of up to 0.86 m s(^-1). It was found that as prey density increased, animals, generally, made fewer dives of shorter duration, more of which were successful, although there was considerable individual variation. For habitat complexity, animals, generally, behaved similarly if hides were arranged randomly or in clumps, but when hides were regularly distributed, fewer hide visit dives were performed. However, mean time on bottom tended to be longer, resulting in little difference in foraging efficiency between the three conditions. A brief review of individual strategies revealed that there were considerable individual differences in foraging strategy. These were not related to sex, thus, some individuals consistently used a strategy of many short duration dives, generally visiting only one hide per dive. Others opted for fewer, longer duration, dives, generally involving more than one hide visit. Further, mean dive duration was not related to body weight. An investigation into the maximum underwater swimming speed achieved by mink showed that animals could reach speeds of over 1 m s(^-1). However, comparison with swimming speeds of fish species preyed on by mink, revealed that the fish swam faster. A review of the habits of the fish eaten, however, revealed that most were sedentary, bottom dwellers. The implications from this are that commercially important fish, e.g. salmon and trout, may well be taken mainly as diseased or spent individuals. The overall conclusion reached was that mink are highly versatile mustelids, and have 'specialised' in the ability to utilize both terrestrial and aquatic habitats.

No description available.

Slugs are important pests in many agricultural crops and potential biological control agents are being studied as an alternative to molluscicide application. The role of the carabids Pterostichus madidus (Fabricius) and Nebria brevicollis (Fabricius) as predators of the slug Deroceras reticulatum (MUller) was examined in the laboratory. These generalist beetle species were only capable of killing small, healthy slugs (<0.1 ig) as they were unable to overcome the defence mucus production of larger slugs. Dead slugs were scavenged in preference to killing healthy slugs. The relatively high proportion of positive serological results from field caught carabids may reflect a high scavenging rate rather than actual predation on live slugs. Slugs are difficult prey items for generalist beetles to overcome due to their defence mucus production. Results suggest that few slugs will be consumed in the presence of alternative prey which are less difficult for beetles to overcome. Slugs which could no longer produce defence mucus were readily attacked by both beetle species. Although beetles killed few healthy slugs the presence of beetles influenced slug behaviour with slugs of all sizes foraging for shorter periods of time. Any reduction in slug activity on the soil surface would in turn lead to a reduction in seedling damage. The results suggest that the role of potential predators in pest control can only be evaluated fully with a detailed understanding of their behaviour.

Here I examine five non-migratory sympatric bat species that are similar in their morphology and general ecology: Eptesicus fuscus, three myotid bats, Myotis leibii, M. lucifugus, Myotis septentrionalis, and Pipistrellus (= Perimyotis) subflavus. By examining echolocation call structure, wing and jaw morphology and diet, I defined finer niche differences between species. M. lucifugus and M. septentrionalis differ in the relative abundance of moths in their diet. My results on skull morphology suggest M. lucifugus consumes harder insects than M. septentrionalis. Conversely, my data suggests M. leibii is not as efficient within a cluttered habitat but is capable of foraging in edge habitats. Eptesicus fuscus is capable of efficiently consuming larger insects whereas P. subflavus has echolocation and jaw characteristics that indicate specialization in smaller insects. Significant differences amongst these 5 species are evident based on my data of overall morphology and diet.

Here I examine five non-migratory sympatric bat species that are similar in their morphology and general ecology: Eptesicus fuscus, three myotid bats, Myotis leibii, M. lucifugus, Myotis septentrionalis, and Pipistrellus (= Perimyotis) subflavus. By examining echolocation call structure, wing and jaw morphology and diet, I defined finer niche differences between species. M. lucifugus and M. septentrionalis differ in the relative abundance of moths in their diet. My results on skull morphology suggest M. lucifugus consumes harder insects than M. septentrionalis. Conversely, my data suggests M. leibii is not as efficient within a cluttered habitat but is capable of foraging in edge habitats. Eptesicus fuscus is capable of efficiently consuming larger insects whereas P. subflavus has echolocation and jaw characteristics that indicate specialization in smaller insects. Significant differences amongst these 5 species are evident based on my data of overall morphology and diet.