The use of resources by otters (<I>Lutra lutra</I> L.) living along coasts and streams in Southwest Portugal was described, and related to their spatial and temporal patterns of availability. The use of freshwater along coasts was inferred from the spatial distribution of spraints, and from radio-tracking. Spraints were mostly concentrated at the mouth of streams that provided freshwater throughout the dry season, and where rest-sites were found within dense thickets of brambles. Rest-sites were considered a scarce resource, because they seemed to be associated with the few permanent sources of freshwater. Along the coast prey availability was highest in winter and lowest in later summer and autumn. The corkwing wrasse was the dominant prey, and the seasonal variation in diet was primarily related to fluctuations in its abundance: wrasse were consumed when they were most abundant, other prey being taken to compensate for lows in their availability. In streams there were large year-to-year fluctuations in fish abundance, and these were related to the severity of summer droughts. Spring was probably the period of maximum prey abundance. Eels and crayfish were the dominant prey, but cyprinids, toads and frogs were also important seasonally. Prey were consumed relative to availability, except eels, which were consumed less than expected during the peak abundance of crayfish. Crayfish and eels were more associated in spraints that expected by chance. The introduction of the American crayfish to Iberia contributed to increase food abundance from spring to early autumn. Breeding of otters occurred seasonally, but births were earlier on the coast (October-December) than inland (January-March), most probably as a consequence of the seasonal patterns of food availability. Litter sizes inland were larger than on the coast. Differences between otter habitats in Southwest Portugal and elsewhere were discussed. A conservation strategy for otters in this region was developed.

Understanding how species respond to variations in weather patterns will be crucial to improve our predictions about how species will cope with climate change. The Verreaux's Eagle (Aquila verreauxii) and its primary prey species the Rock Hyrax (Procavia capensis) and Yellow-spotted Hyrax (Heterohyrax brucei) have been monitored by a long-term citizen science project in the Matobo Hills, Zimbabwe. A previous study associated rainfall patterns with the establishment, breeding density and productivity of Verreaux's Eagles. Fluctuations in hyrax populations have been attributed to fluctuations in rainfall and drought. However, these studies have been limited by the use of total annual rainfall instead of targeted rainfall periods of when biological outcomes are most sensitive to weather phenomena. This study explored critical climate sensitivity windows influencing the Verreaux's Eagle's reading performance and the abundance of its main prey species. We used observations of 109 nests over 37 years (1984-2019) and counts from 20 hyrax den sites for 13 years (1993-2005), together with remotely sensed rainfall data. The probability of attempting to breeding and the probability of producing a fledgling was negatively associated with rainfall. For breeding attempt, the rainfall during June and July, 11-10 months before laying was the most relevant, whereas, for productivity, the rainfall during December to March, nine-five months before fledging was the most relevant. However, the relationship between the rainfall signal and breeding productivity was not significant. Hyrax abundance had a negative quadratic relationship with mean rainfall against their respective climate windows, whereby the abundance of adult and sub-adult hyrax increased with rainfall during July–September but declined thereafter at greater rainfall levels. The abundance of hyrax did not have a significant relationship with the breeding outcomes of the Verreaux's Eagles. This study shows the complexity of the causal relationships between climate and biological outcomes and also the value of long-term data to understanding the impacts of variations in weather patterns to better understand predator-prey dynamics.

The stomachs of 183 bigeye tuna (Thunnus obesus) were collected from three Taiwanese longline vessels operating in the western Indian Ocean during the period from April to December 2006. Their fork lengths ranged from 89 cm to 198 cm. Distinguishable prey species, belonging to 28 families, consisted mostly of fishes, crustaceans, and cephalopods. Fourteen prey items were newly recorded, among them, five families (Anoplogastridae, Bothidae, Grammicolepididae, Pinguipedidae, and Sciaenidae) were firstly recorded as the diet of bigeye tuna. Two special dietary species were found for the first time. Oplophorus gracilirostris, the dominant numerical dietary species, had not been previously recorded; however, O. typus had been recorded in the past. The other special prey species found, Macrurocyttus acanthopodus (Grammicolepididae), was not only the first record in the stomach of bigeye tuna but also the first record in the Indian Ocean. The largest body length among prey species was 655 mm for an Alepisaurus ferox. The number of prey species appeared to decrease with the increasing size of the bigeye tuna, and larger Indian bigeye tuna tended to feed on larger prey species. In the stomachs of the bigeye tuna, Oplophorus gracilirostris was the most frequently found prey species (56.8%). The three numerical most dominant prey species were Oplophorus gracilirostris (38.2%), Charybdis smithii (8.8%), and Alepisaurus ferox (3.6%). In addition, the fish prey item, Alepisaurus ferox, had the highest percentage of prey weight. The total percentage of prey weight for prey fishes is similar to that reported in previous research, but the average weight of Alepisaurus ferox is heavier than the previous report. Additionally, the percentage of prey weight for Paralepididae is lower than the results of previous studies. Moreover, the occurrence and percentage of the number of Oplophorus gracilirostris are distinctly higher than the results of previous studies. These findings indicate that the percentage of mean preys number exist seasonal effect. Alepisaurus ferox was the most numerous prey in May to July; Oplophorus gracilirostris was the most numerous prey at 200 m depth in August to October 45¢XE to east; Charybdis smithii was the most numerous prey at 50 m depth in August to October 45¢XE to west. A possible reason to explain this phenomenon is that there are strong feeding migratory behavior in bigeye tuna.

A variety of prey species are able to detect predators by odours emanating from their urine, feces, fur and anal glands. However, it is unknown whether the odour of a predator’s blood also contains information signalling “predator” to a prey. The aim of the present study was therefore to assess if blood odour from a cat elicits avoidance or anxiety responses in CD-1 mice (Mus musculus). A two-compartment test arena was used to assess place preference, motor activity and fecal excretions when the mice were simultaneously presented with cat blood and a blank control. Additionally, the mice were tested with horse blood and N-pentyl acetate, a fruity odour. The mice did not show avoidance of any of the three odours. Nevertheless, the mice were significantly less active when exposed to cat blood in comparison to horse blood, but did not increase defecation when exposed to cat blood. This suggests that the information mice get by the odour of cat blood did not contain the signal “predator”.

It is essential for prey species to be able to detect predators to avoid them. The sense of smell is used by a number of prey species for this purpose. The aim of the present study was to assess if one of the odourants that make up a predator odour is sufficient to induce a behavioural response in mice (Mus musculus). Two predator odourants were used, 2,2-dimethylthietane and methyl-2-phenylethyl sulfide, which are both found in the secretions of natural predators of mice. An odourant found in fruits, n-pentyl acetate, was also used. All three odourants were presented at a concentration that was a factor of 100 above the olfactory detection threshold of mice. Ten adult predator-naïve CD-1 mice were individually put in a two-compartment chamber one of which contained an odourant while the other contained a near-odourless solvent (diethyl phthalate). The results indicated that methyl-2-phenylethyl sulfide was actively avoided by the mice. Towards 2,2-dimethylthietane and n-pentyl acetate, in contrast, the mice behaved indifferent. Further, the results suggest a significant correlation between the number of switches between the two compartments of the test chamber and the test sessions when the animals were presented with n-pentyl acetate, but not when they were presented with the predator odourants. The results support the notion of an innate fear response towards the predator odourant methyl-2-phenylethyl sulfide in mice, but further studies with more animals and different concentrations of the odourants are necessary.

Piscivorous birds are an integrated part of lake and coastline ecosystems. Despite decades of research it is yet unclear what influence fish eating birds have on the fish community. The aim of this literature study was to focus on how two fish eating birds, Great Cormorant and Great Crested Grebe, influence the fish community in shallow and eutrophic lakes. Different types of analysis methods have been used when doing research on the subject, including pellet analysis, stomach content analysis, tagging of fishes by “PIT”-techniques and analysis by observation. Results show that conclusions by studies tend to vary, but generally higher bird density, lower water temperature and a relatively high turbidity contribute to a higher influence on the fish community. Both bird species are opportunistic in their choice of food and catch prey of the species that occur locally. Both species also limit themselves in the prey size, but the choice vary over seasons because of water temperature and the birds requirements in association with breeding and migration. The significant level of influence seems to be when predation is conducted on younger and smaller fishes. The influence on the fish size can also be indirect, where predation on smaller individuals prevent fishes from becoming older and bigger. As studies tend to deviate in conclusion, no general answer to this issue can be given at present. Comprehensive research with several years of full control over both fish-and bird population is needed to find the proper conclusion.

Weltweit sind viele Populationen großer Raubtiere bedroht. Die Suche nach Wegen zur Erhaltung und Wiederherstellung von Populationen großer Raubtiere ist daher ein zentrales Naturschutzziel. In einigen Regionen erholen sich die Populationen jedoch auch, was der Wissenschaft eine hervorragende Möglichkeit bietet potentielle Wege zum Schutz von Raubtieren zu identifizieren. Das Ziel dieser Arbeit war es, die Voraussetzungen, die eine Erholung von Raubtierpopulationen begünstigen, besser zu verstehen. Am Beispiel der sich erholenden Population des Persischen Leoparden im Kaukasus beantwortet diese Arbeit die folgenden Forschungsfragen: (1) Bietet die Ökoregion des Kaukasus einen geeigneten, sicheren und zusammenhängenden Lebensraum für Persische Leoparden und ihre Beutetiere? (2) Was sind wirksame Schutzstrategien, die eine Erholung der Population des Persischen Leoparden im Kaukasus begünstigen? Die Ergebnisse dieser Arbeit lassen den Schluss zu, dass für Leoparden und ihre Beutetiere im Kaukasus großflächig geeigneter Lebensraum vorhanden ist. Trotz dieser günstigen Ausgangsposition für den Artenschutz zeigt diese Arbeit jedoch auch klar auf, dass Schutzmaßnahmen erforderlich sind, um direkte Bedrohungen abzumildern. Als wichtigsten Faktor für eine Erholung der Leopardenpopulation identifiziert diese Arbeit das Verhindern von Tötungen. Diese Arbeit verdeutlicht somit die wichtige Rolle von Konfliktminderung zwischen Menschen und Raubtieren, um die daraus resultierende Tötung von Raubtieren zu verhindern. Darüber hinaus unterstreicht diese Dissertation die Notwendigkeit der Vernetzung sicherer Lebensräume und den Wert von internationaler Zusammenarbeit zur Förderung der Genesung von Populationen großer Raubtiere. Zusammengefasst liefert diese Arbeit Einblicke in Bedingungen, die die Genesung von Großraubtieren fördern, und umreißt mögliche zukünftige Wege eines vom Aussterben bedrohten Raubtiers in einem globalen Biodiversitäts-Hotspot. / Large carnivore populations are threatened globally. This is worrisome because of their intrinsic value and their importance for ecosystems and humans. Finding ways to maintain and restore large carnivore populations is therefore a central goal for conservation. Interestingly, large carnivores are also returning to areas where they were extirpated before, which provides a great opportunity for conservation science to identify pathways to safeguard large carnivore populations. The overall goal of this thesis was to better understand the conditions that foster large carnivore recoveries. Gaining a better understanding of large carnivore recoveries is challenging though, because it requires working across broad areas, where data on environmental characteristics and prey species is often limited and inconsistent. Using the Persian leopard recovery in the Caucasus ecoregion as an example, the specific research questions of this thesis were: (1) Does the Caucasus ecoregion have suitable, safe, and connected habitat for Persian leopards and their prey? (2) What are effective management strategies to foster the recovery of Persian leopards in the Caucasus? Results revealed that suitable habitat for Persian leopards and their prey is widespread in the Caucasus. However, habitat patches are often not safe and conservation efforts are needed to mitigate threats and restore, protect, and connect populations of leopards and their prey. Reducing the persecution of leopards seems the most important strategy to foster leopard recovery in the Caucasus. For large carnivore recoveries in general, this thesis underpins the importance of human-carnivore conflict mitigation to prevent killings of carnivores, particularly in areas where populations are small. Further, this thesis underlines the need of improving connectivity among safe habitat patches and the value of international cooperation. Overall, this thesis provides insights into conditions that foster large carnivore recovery and outlines potential future pathways for a critically endangered apex predator in a global biodiversity hotspot.

[For the Abstract, please see the PDF files below, namely "front.pdf"] CONTENTS. Chapter 1 Introduction. Chapter 2 Gross and microscopic visceral anatomy of the male Cape fur seal with reference to organ size and growth. Chapter 3 Age determination and growth in the male Cape fur seal: part one, external body. Chapter 4 Age determination and growth in the male Cape fur seal: part two, skull. Chapter 5 Age determination and growth in the male Cape fur seal: part three, baculum. Chapter 6 Suture age as an indicator of physiological age in the male Cape fur seal. Chapter 7 Sexual dimorphism in the adult Cape fur seal: standard body length and skull morphology. Chapter 8 Reproduction in the male Cape fur seal: age at puberty and annual cycle of the testis. Chapter 9 Diet and foraging behaviour of the Cape fur seal. Chapter 10(a) The Impact of the fur seal industry on the distribution and abundance of Cape fur seals. Chapter 10(b) South African Airforce wildlife rescue: Cape fur seal pups washed from Black Rocks, Algoa Bay, during heavy seas, December 1976. Chapter 11(a) Operational interactions between Cape fur seals and fisheries: part one, trawl fishing. Chapter 11(b) Operational interactions between Cape fur seals and fisheries: part two, squid jigging and line fishing. Chapter 11(c) Operational interactions between Cape fur seals and fisheries: part three, entanglement in man-made debris. Chapter 12 Concentrations of heavy metals (Cd, Cu, Pb, Ni & Zn) and organochlorine contaminants (PCBs, DDT, DDE & DDD) in the blubber of Cape fur seals. Chapter 13 Endoparasites of the Cape fur seal. Chapter 14(a) Preliminary investigations of shark predation on Cape fur seals. Chapter 14(b) Aggressive behaviour of an adult male Cape fur seal towards a great white shark Carcharodon carcharias. Chapter 15 Conclusions and future directions.