Predatory and Foraging Behaviour of Brown Hyenas (Parahyaena brunnea (Thunberg, 1820)) at Cape Fur Seal (Arctocephalus pusillus pusillus Schreber, 1776) Colonies.

Diss. Uni Hamburg. 210 Seiten.

Volltext: https://ediss.sub.uni-hamburg.de/bitstream/ediss/1584/1/IWDissertation.pdf

Conclusions:

The predatory and foraging behaviour of brown hyenas (Parahyaena brunnea) was observed at mainland Cape fur seal (Arctocephalus pusillus pusillus) breeding colonies in the southern Namib Desert. The objectives of this study were to

(1) assess the availability, condition and accessibility of seals for brown hyenas,
(2) evaluate the importance of the coast for brown hyena abundance, movement and energy budget,
(3) determine factors influencing the foraging related time budget of brown hyenas,
(4) assess feeding preferences, and
(5) examine the consumption of prey.

Behavioural observations were conducted at the Van Reenen Bay seal colony and seal pup mortality data was recorded at the Wolf Bay seal colony.
GPS collars were fitted on coastal brown hyenas to determine their movement. Live seal pups were available for brown hyenas all year round, but their increasing size, mobility and activity, as well as the attendance pattern of adult females may influence the brown hyena’s foraging behaviour. Many dead pups were available to scavenge during the pupping season and represented an easy and safe way to obtain food.

In general, predators and prey are mutually influenced by each others behaviours. In Chapter 4 the anti-predator strategies of Cape fur seals towards brown hyenas were reviewed and assessed with regard to their influence on the hyena’s foraging strategies. Although Cape fur seals showed a near complete lack of anti-predator behaviour, the predator-prey system is possibly donor-controlled (Chapter 5) and the usual depensatory effect on prey populations that face novel or exotic predators is not expected (see Sinclair et al. 1998). The numerical response of predators to increased prey numbers as predicted by Holling (1959, 1965) could not be seen in this study (Chapter 5), and seasonality in the availability of seal pups, therefore, may limit brown hyena population growth, and may contribute to the maintenance of large home ranges despite localised food sources. However, coastal brown hyenas’ daily movements were less than that of inland ones, they have a lower field metabolic rate, and hence may consume less food.

Brown hyenas preferred to kill seal pups despite the availability of carrion (Chapter 6). The predation rate was unrelated to carrion availability, but the absolute number of kills was positively correlated to seal pup density. Increasing  seal pup density led to an increase in brown hyena capture rate and hunting efficiency. Furthermore the overabundance of easy and vulnerable prey led to surplus kills. However, brown hyenas foraged opportunistically by scavenging, killing and caching seal pups in proportion to their occurrence at the colony (Chapter 7 and 8), and hence, caused an additional impact on seal pup mortality by not only choosing the doomed surplus. The killing of seal pups seemed to be unrelated to hunger, and surplus killing occurred throughout the study period. Brown hyenas preferred to consume larger and heavier prey, but a large proportion of the brown hyena’s prey was only partially consumed (Chapter 8). Selectivity increased with seal pup density, and feeding and handling times per prey item were reduced. Brown hyenas showed a preference for brain tissue, and the consumption of brain tissue may quickly satisfy the brown hyena’s metabolic requirements, or may be important to keep a positive water balance. Although black-backed jackals (Canis mesomelas) outnumber brown hyenas and are their main competitors at seal colonies, they did not influence the brown hyena’s foraging strategy.

Brown hyenas, therefore, behave opportunistically regarding their feeding preferences and optimally regarding the consumption of seals. Seal pup density influences the brown hyena’s predatory and foraging behaviour, and seasonality in seal availability may limit brown hyena abundance and influence their movement patterns. Future observations of foraging brown hyenas outside the pupping season and at night could yield additional interesting information about adaptations in predatory and foraging behaviour to changes in seal behaviour, abundance and attendance.

wiesel-biblio

Exploitation of California Sea Lions, Zalophus californianus, Prior to 1972 .

Marine Fisheries Review  47 (1): 36-38

Summary:

This article summarizes the results of an investigation made into historical sealing activities on the California coast and Channel Islands. Of primary interest were the numbers of California sea lions, Zalophus caiifornianus, killed on San Miguel Island. The harvesting of the northern or Steller sea lion, Eumetopias jubatus, is also discussed. Literature was reviewed for records on the number of sea lions taken for commercial purposes. Many other potential sources of information on numbers of animals killed were also investigated.

cass-biblio

Phoca sibirica.

Mammalian Species No. 188: 1-6. 4 Abbildungen.

Veröffentlicht am 23. November 1982 durch die American Society of Mammalogists.

Volltext:

https://academic.oup.com/mspecies/article-abstract/doi/10.2307/3503825/2600254?redirectedFrom=PDF

thomas-biblio

Seals of the World. 

2. Auflage. 240 Seiten mit zahlreichen s/w-Fotos, Strichzeichnungen, Karten und Tabellen.
Oxford University Press & British Museum (Natural History). ISBN 0-19858513-6.

Inhalt: 

Updated and enhanced edition of that published twenty years ago. Includes maps, excellent illustrations, species accounts, a long section on pinniped anatomy and pathology, excellent appendices, indexes and bibliography.

Lungenwurminfektionen bei Robben und serologische Nachweismöglichkeiten.

A recombinant antigen-based enzyme-linked immunosorbent assay (ELISA) for lungworm detection in seals.

In: Parasites & Vectors 8 (2015) 443.  ISSN 1756-3305

Institut für Terrestrische und Aquatische Wildtierforschung, Institut für Parasitologie, beides Tierärztliche Hochschule Hannover
1. Betreuer: Prof. Prof. h.c. Dr. Ursula Siebert
2. Betreuer: Christina Strube, Prof. Dr. med. vet., PhD
Tierärztliche Hochschule Hannover
Tierpark Nordhorn

Ganzer Text

Zusammenfassung:

Die Forschungsarbeit beinhaltet die Etablierung eines serologischen Nachweisverfahrens zur Detektion einer Lungenwurminfektion bei Seehunden und Kegelrobben. Die Lungennematoden Otostrongylus circumlitus und Parafilaroides gymnurus kommen bei Seehunden häufiger und mit größeren Wurmbürden als bei Kegelrobben vor. Sie stellen bei an deutschen Küsten gefundenen Seehunden die pathogensten Parasitenarten dar: Die Nematoden, die im Respirationstrakt  ihrer vorwiegend unter einem Jahr alten Wirte parasitieren, verursachen Läsionen, die sich durch bakterielle Sekundärinfektionen zu schwerwiegenden Bronchopneumonien entwickeln und zum Tod der Robben führen können.

Eine individuelle Detektion von Lungenwurminfektion kann meist erst post mortem festgestellt werden. Das Paper beschreibt die serologische Nachweismöglichkeit in Form eines rekombinanten, antigen- basierten enzyme-linked immunosorbent assays (ELISA), der die Lungenwurmantikörper in Blutproben von Robben detektieren kann. Damit ließen sich Dynamik und Immunologie der Lungenwurminfektion effektiver erforschen. Die Bedeutung und der Verlauf eines Parasitenbefalls für den Gesundheitszustand könnten bei freilebenden und bei Tieren in menschlicher Obhut engmaschig beobachtet werden. Ein ELISA kann ermöglichen, die starke Altersabhängigkeit im Befall und einen eventuellen Anstieg der Infektionsrate in der Population zu ergründen. Eine verstärkte Anfälligkeit für Lungenwurminfektionen könnte z.B. durch erhöhte Schadstoffbelastungen in der Nord- und Ostsee, die eine Immunsuppression bei den Robben verursacht, einhergehen. Anthropogene Auswirkungen auf die einheimischen Meeressäugetiere durch die verstärkte Nutzung der deutschen Meeresgebiete können so beleuchtet werden und zum Verständnis, Management und Schutz der Robbenbestände in Nord- und Ostsee beitragen.

Abstract:

Pinnipeds are frequently infected by the lungworms Otostrongylus circumlitus and Parafilaroides gymnurus (Metastrongyloidea). Infections are frequently associated with secondary bacterial bronchopneumonia and are often lethal. To date, a reliable lungworm diagnosis in individual seals is only possible during necropsy as examination of faeces collected from resting places does not allow assignment to individuals. Therefore, a diagnostic tool for lungworm detection in living seals is desirable for monitoring health of seals in the wild and in captivity. Previously, an ELISA based on recombinant bovine lungworm major sperm protein (MSP) as diagnostic antigen was developed for lungworm diagnosis in cattle. In the present study, this test was adapted for detection of antibodies against lungworms in harbour (Phoca vitulina) and grey seals (Halichoerus grypus). Furthermore, sera of northern elephant seals (Mirounga angustirostris) were tested to evaluate whether the harbour/grey seal ELISA is suitable for this seal species as well.
Methods
For ELISA evaluation, lungworm-positive and -negative sera of harbour and grey seals were analysed using horseradish peroxidase (HRP)-conjugated Protein A as secondary antibody. Optical density was measured and a receiver operating characteristic (ROC) analysis was performed to determine a cut-off value. Potential cross-reactions were examined by testing serum of seals positive for gastrointestinal and heart nematodes, but negative for lungworm infections. In addition, sera of northern elephant seals were analysed.
Results
Harbour and grey seal serum samples showed significant differences in optical density (OD) between serum of infected and uninfected animals resulting in a cut-off value of 0.422 OD with a specificity of 100% (95% CI: 87.23-100%) and a sensitivity of 97.83% (95% CI: 88.47-99.94%). Cross-reactions with heart or gastrointestinal nematodes were not observed. Analysis of northern elephant seal samples resulted in detection of antibodies in animals positive for lungworm larvae at faecal examination.
Conclusions
The ELISA presented is a valuable method for detection of lungworm infections in live harbour and grey seals, providing a monitoring tool to reveal epidemiological dynamics of lungworm infections during health surveillance in free-ranging seals. Furthermore, ELISA results may aid institutions with harbour and grey seals under human care on decisions regarding anthelminthic treatment of individual animals.

ulrich-biblio

Draft Husbandry Guidelines for true seals (Phocidae).

For Review by the EAZA Marine Mammal TAG

Abstract:

Within EAZA the need to improve the standards in zoos was the reason to start writing Husbandry Guidelines. Husbandry Guidelines are housing and care guidelines with the objective to guarantee optimal conditions for welfare and reproduction of captive animal populations. They have to fulfil the need for co-operation and information exchange between EAZA zoos and to improve husbandry knowledge. The marine mammal TAG is responsible for writing the guidelines for marine mammals, in this case the true seals. The goal of this study is to design Husbandry Guidelines for keeping true seals in captivity, by giving an overview of all aspects concerning the responsible husbandry and care of true seals. To accomplice this objective the following research question had to be answered: How to guarantee the optimal conditions for welfare and reproduction of true seals in EAZA zoos?

This draft version of Husbandry Guidelines for captive true seals is compiled by studying the biology and field data, as well as the management in captivity of true seals. The current situation is described, literature research is performed, important subjects are determined, experts are consulted and finally all these data are compiled into a draft version Husbandry Guidelines for true seals. The structure of the Husbandry Guidelines is set up according to the standard table of contents assessed by EAZA, and the draft version Husbandry Guidelines for eared seals by Osinga/ De Wit (2002). This draft version has to be reviewed by experts in the Marine Mammal TAG before it becomes a final version of Husbandry Guidelines for true seals.
The Husbandry Guidelines are divided in two parts in which both the data of animals in the wild and the management in captivity are described. In section A information is given on the biology and field data of true seals. Special attention was paid to the species that are kept in EAZA zoos now. In section B all aspects concerning management in captivity are described.

Most information is based on experiences and not on scientific knowledge. Additional research is necessary to improve the quality of these Husbandry Guidelines.

meijer-biblio

Husbandry Guidelines for Eared Seals (Otariidae).

Edited and Compiled by the EAZA Marine Mammal TAG. Ouwehands Dierenpark, Rhenen

Abstract

Husbandry guidelines are housing and care guidelines with the objective to guarantee optimal conditions for wellbeing and reproduction of captive populations. It has to fulfil the need for cooperation and information exchange between EAZA zoos and to improve husbandry knowledge.

The marine mammal TAG is responsible for writing the guidelines for marine mammals. The goal of this study is to design husbandry guidelines for keeping eared seals (Otariidae) in captivity, by giving an overview of all aspects concerning the responsible husbandry and care of eared seals. To accomplice this objective the following research question had to be answered: How to guarantee the optimal conditions for welfare and reproduction of eared seals in EAZA zoos?

This manual for husbandry of captive eared seals is compiled by studying the biology and field data, as well as the management in captivity of eared seals. The current situation was described, literature research was performed, extra important subjects were determined, experts were consulted and finally all this data was brought together. The structure of the husbandry guidelines is set up according to the standard table of contents assessed by EAZA.

The husbandry guidelines are divided in two parts in which both the data of wild animals and the management in captivity are described. In section A information is given on the biology and field data of eared seals, which is important for good management of husbandry in captivity, to adjust the captive situations as much as possible to the needs of the animals. Extra attention was paid to the six species kept in EAZA zoos. In section B the management in captivity is described. In the first chapter the enclosure for eared seals is described including minimum requirements for the dimensions. Extra attention was paid to good alternatives for chlorine water treatment systems.

Chapter two deals with the feeding; the fish species and quantity were described, as well as the process of maintaining quality during transport, storage and thawing. Chapter three is about behaviour and social structure. Behaviour problems were discussed and advice is given to prevent them. By social structure the composition and group size is an important factor in wellbeing. Attention was paid to changing group structure and sharing the enclosure with other species. In chapter four the different tools for enriching eared seals in captivity are summarised. In chapter five the different stages of reproduction in captivity are described, with attention for the changes in behaviour. Different methods for weaning and forced feeding were given. Chapter six is about all handling procedures. First the catching and restraining were discussed, then transport, followed by safety and finally the training of eared seals. In chapter seven information of recent literature sources concerning the health and welfare of captive eared seals were included. Chapter eight is about the population management of the animals present in the EAZA zoos. National and European legislation is described in chapter nine. In chapter ten suggestions for additional research are given. In the attachments the following parts are included: the EAZA standards for accommodation and care of wild animals in zoos, Canadian and American legislation concerning space requirements and a checklist for the building of an enclosure for eared seals.

Most information is based on experiences and not on scientific knowledge. Additional research is necessary to lay down the knowledge of people working in the field of marine mammal husbandry and to extend the scientific knowledge. A more exhaustive literature study and consulting of experts can give more specific guidelines.

meijer-biblio

Zwillinge bei Kalifornischen Seelöwen (Zalophus californianus) im Zoologischen Garten Wuppertal.

Zool. Garten (N. F.) 71 (2): 101-103. Urban & Fischer Verlag Jena. ISSN: 0044-5169

Voller Text

schürer-biblio

Untersuchungen zu den Sozialbeziehungen von Kalifornischen Seelöwen (Zalophus californius californius) und Seehunden (Phoca vitulina) in der Gemeinschaftshaltung des Tiergartens Nürnberg.

München, GRIN Verlag GmbH, http://www.diplomarbeiten24.de/vorschau/66110.html
ISBN (eBook): 978-3-638-58419-7. DOI: 10.3239/9783638584197. Dateigröße: 2299 KB

Examensarbeit im Fach Biologie

144 Seiten

Ruprecht-Karls-Universität Heidelberg

Zusammenfassung

Seit dem Spätsommer 2005 leben im Aqua Park, einer Wassergehegeanlage des Nürnberger Tiergartens, Kalifornische Seelöwen (Zalophus californius californius) gemeinsam mit Gemeinen Seehunden (Phoca vitulina). Diese Vergesellschaftung bietet eine der seltenen Möglichkeiten, das Verhalten der beiden sozial lebenden Arten nicht nur auf Sozialbeziehungen innerhalb der Art hin zu untersuchen, sondern auch in Bezug auf zwischenartliche soziale Kontakten.

Kalifornische Seelöwen sind polygam, d.h. sie bilden Haremsverbände, die von erwachsenen Männchen dominiert werden. Gemeine Seehunde schwimmen in der Regel einzeln, tummeln sich aber an Land zumeist in kleineren Gruppen, die allerdings keine festen sozialen Beziehungen haben.

Obwohl eine Zoohaltung den Tieren in keiner Weise Lebensbedingungen bieten kann, die vollständig denen in Freiheit entsprechen, können Studien über das Verhalten von Tieren in Gefangenschaft durchaus Aufschluss über Verhaltensspektren geben, die auch in freier Wildbahn auftreten.

In dem Seelöwen-Seehundgehege des Aqua Parks leben derzeit neun erwachsene Seelöwen: Der Bulle Patrick und acht Weibchen von denen drei zur Zeit der Beobachtung Jungtiere hatten. Die Seehundfamilie ist wesentlich kleiner, sie besteht nur aus dem jungen Geschwisterpaar Finchen und Nele.

Fragestellung:

Folgende Hypothesen wurden aufgestellt und auf ihre Richtigkeit hin untersucht:

•    Nullhypothese: Die Tiere haben untereinander gleich stark ausgeprägte soziale Kontakte.
•    Alternativhypothese: Es zeigen sich deutliche Unterschiede in der Intensität der sozialen Kontakte zwischen den Tieren.

•    Nullhypothese: Die Tiere nutzen das ihnen zu Verfügung stehende Gehege gleichmäßig.
•    Alternativhypothese: Die Tiere nutzen das ihnen zu Verfügung stehende Gehege nicht gleichmäßig.

kurz-biblio

European Studbook for the South American Fur Seal (Arctocephalus australis).

6th Edition 2011. 38 Seiten. Zoo Dortmund.

gatz-biblio