H. Kruuk

H. Kruuk
University of Aberdeen | ABDN · School of Biological Sciences

About

73
Publications
18,560
Reads
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4,926
Citations
Additional affiliations
August 1990 - December 1990
University of New England (Australia)
Position
  • Visiting Research Fellow
Description
  • research on platypus and spotted-tailed quoll
June 1971 - April 1975
University of Oxford
Position
  • Senior Researcher
Description
  • Research Group of Niko Tinbergen

Publications

Publications (73)
Article
This paper discusses the relationship between the distribution and biomass of the main prey of European badgers, Meles meles and the badgers group size, territory size and population density. The distribution of areas rich in earthworms, Lumbricus spp., is correlated with badger range size, whilst badger group size increases with the biomass of wor...
Article
This paper describes aspects of the biological function of the sub-caudal scent gland of the European badger. Chemical analyses of the secretion reveal that it contains information potentially useful in allowing individual identity and group membership. There is no evidence that the secretion contains information on the sex of its producer.
Article
The paper describes habitat preferences, spacing, range sizes, group composition and territorial behaviour of the European badger in a study area in southern England. Animals were followed at night with the aid of radio-location and night-vision equipment, and colour-marked food was used to establish range-size.
Article
In several field observations, foxes, Spotted hyaenas and other carnivores killed many more prey individuals than they could eat. Functional and causal aspects of this phenomenon are discussed and the conclusion is reached that these surplus kills are the consequence of behavioural compromises in both predator and prey to meet opposing environmenta...
Article
The distribution of otter dens (holts) and otter droppings (spraints) which also function as scent markers, is described for an area of coast in north-west Scotland, and some observations are presented of the otters' movements and foraging. Otter holts were spaced out at an average distance of 11 km, and spraints were concentrated around the holts....
Article
We describe changes in age composition and body condition of a sample of 310 otter carcasses collected between 1982 and 1994 in Scotland. There was a decline of mean age and death in NE Scotland, which was absent in some other areas. The decline was present especially in females, and due to an increase in numbers of immature otters. However, mean a...
Article
The effects of water temperature (Tw) on core body temperature (Tb) and foraging behaviour were studied in four free-ranging and one captive otter Lutra lutra in NE Scotland. The free-ranging animals were observed in and around two freshwater lochs, and measurements were made of Tw (2–16°C), Tb at the beginning and end of swimming bouts, lengths of...
Article
Full-text available
Eurasian otters (Lutra lutra) inhabiting a marine environment need to wash in freshwater in order to maintain the insulating properties of their fur. Use of freshwater pools by otters on the coast of Skye was studied in order to determine factors influencing pool choice. A number of characteristics were recorded for all pools present. Otter spraint...
Article
Otters Lutra lutra in Shetland feed almost exclusively in the sea. Their diet was assessed from direct observations of 13, 313 dives, of which 27% were successful, and 2028 prey could be identified. The results are compared with published data on the availability offish for different seasons, time of day, state of tide, and different types of coast...
Article
The dispersion of otters Lutra lutra was studied along the coasts of an area of Shetland. The population was relatively stable, with about one adult otter per kilometre of coast. They fished diurnally in a strip of water usually within 100 m of the shore. Females lived in exclusive group ranges, occupied by up to four females, with well-defined bou...
Article
Otters Lutra lutra L. which feed in the sea in Scotland frequently wash in fresh water. Experiments were carried out with otter pelts and with captive otters, to study the biological function of this behaviour. In vitro, the fur of otters lost much of its thermal insulation after five soakings in sea water and subsequent drying. Otters were fed in...
Article
Daily activity of Eurasian otters (Lutra lutra) was recorded along the coast of Shetland, UK, in the summer of 1984. Data of three otters fitted with radio-transmitters were analysed in detail. Compared to sea otters (Enhydra lutris), these otters spent up to 4.5 times less time per day hunting (12%), but devoted the same time per day to grooming (...
Article
Observations were made on spotted-necked otter and the Cape clawless otter in Lake Victoria, Tanzania. Spotted-necked otters lived mostly in small packs. Their prey consisted mainly of cichlid fishes. A method is described for estimating prey size from the diameter of fish eyelenses found in the otters' faeces. Spotted-necked otters took mostly sma...
Article
(1) Food selection of aardwolves was studied by a comparison of faecal contents with available termite populations. Observations are reported on the foraging behaviour, and on aspects of termite biology which expose various species to predation. (2) The aardwolf diet shows a very high selectivity for one species of termite, Trinervitermes bettonian...
Article
Observations are presented on food, foraging behaviour, ranging and some social behaviour patterns of the striped hyaena; these observations are compared with similar ones on spotted hyaenas. Striped hyaenas are more omnivorous than spotted ones, scavenging a great deal and eating insects, fruits and small vertebrate prey. However, the diets of the...
Article
Three thousand year old engravings (petroglyphs) probably of otters Lutra lutra were found in a Bronze Age burial site in Kivik, southern Sweden. The postures of the animals in the very prominent, stylised images, sitting upright, suggests that they represent captive otters, which had an important place in Scandinavian bronze age society.
Article
Full-text available
The relationship between microsatellite diversity and geographical fragmentation and isolation was studied in Scottish populations of the Eurasian otter, Lutra lutra. The geographic range of the study encompassed isolated archipelagos, islands adjacent to the Scottish mainland and both fragmented and continuous mainland populations. Tissue samples...
Article
Full-text available
Predation on adult salmon, Salmo salur L., by otters, Lurra lutra (L.), varied seasonally on the R. Dee, Aberdeenshire, Scotland, being highest during the spawning season in winter. Predation is described for some tributaries of the river. Male fish were caught by otters more often than females, and it is suggested that they were most vulnerable du...
Article
Individual feeding behaviour of the European mink Mustela lutreola and American mink M. vison inhabiting the upper reaches of the Lovat river, NE Belarus was investigated. Three out of the nine individual European minks studied were specialists on frogs (mainly common frog Rana temporaria). The majority (77-97%) of their scats contained frog remain...
Article
Full-text available
Mean yellow eel density and biomass in two adjacent shallow (mean depth c 1·5 m) lochs varied significantly between years. Temporal patterns of density, biomass and size were similar in both soft and rocky substrata in the lochs, although eels were consistently smaller in the latter habitat. In both substrata, average length and weight showed a non...
Article
Body sizes of European mink (Mustela lutreola L.), polecat (M. putorius L.) and American mink (M. vison Schreber) were studied over a 10-year period in an area of north-eastern Belarus, before and after the invasion by American mink, and data are presented on interspecific interactions. On arrival in the study area American mink males were larger t...
Chapter
Introduction This chapter reviews current knowledge and provides previously unpublished data on habitat selection and requirements of the otter (Lutra lutra) in Britain. Such information is evaluated in an attempt to provide a basis for habitat management aimed at otter conservation, and to expose areas where further research is needed. Since the...
Article
During a period in the 1980s when both European mink Mustela lutreola and American mink M. vison were present in Estonia, their food was significantly different. European mink ate a greater proportion of fish and crustaceans, whereas American mink took relatively more mammals and frogs. This was probably related to a difference in habitat selection...
Article
Concentrations of mercury (Hg) were measured in 112 livers of otters from various areas in Scotland during 1986-1992. Mercury concentration varied from 0.3-44.7 ppm (dry). There was a significant positive correlation between Hg in otters and annual rainfall, consistent with an atmospheric origin of mercury pollution. Mercury concentration was highe...
Article
The concentrations of polychlorinated biphenyls (PCBs) and residues of organochlorine pesticides (HEOD and DDE) were measured in livers of otters (Lutra lutra) from different areas in Scotland. Whilst HEOD and DDE occurred at very low concentrations only, PCBs were present in high levels in some areas, the highest in Shetland (geom mean 2.05 ppm we...
Article
Full-text available
A model is described for the general relationship between prey capture rates, predator energy expenditure and time budget, as an aid to evaluating habitat suitability. As an example, otter predation on eels Anguilla anguilla in NE Scotland is discussed. Otters eat small fish; salmonids and eels are prominent prey species. In some study areas there...
Article
The otter population in Shetland has increased significantly between 1988 and 1993, with more animals being found on all coastal strata and in all parts of the archipelago except South Mainland, the only area to show a decline. South Mainland is where the tanker Braer grounded in January 1993 and the subsequent oil spill might have affected the dis...
Article
Latrine use by the spotted-tailed quoll (Dasyurus maculatus: Dasyuridae, Marsupialia) in its natural habitat
Article
Three species of otter, Lutra lutra, L. perspicillata and Aonyx cinerea, occur sympatrically in the Huai Kha Khaeng river and tributaries, Thailand. Small differences in their use of major sections of the river are described, as are variations in micro-habitat and in food: L. perspicillata is the most specialized fish eater, taking larger fish than...
Article
Oxygen consumption ( $\dot{V}O_{2}$ ) was measured in three captive Eurasian otters (Lutra lutra L.) at rest out of water and at rest and at different levels of activity in water of different temperatures. Irrespective of behavior, variation in water temperature ( $T_{w}$ ; °C) accounted for 55% of the variation in $\dot{V}O_{2}$ (mL O₂ [kg · min]⁻...
Article
1. We test the hypotheses that otters Lutra lutra, diving in a marine habitat, prefer shallow water because (a) breathing is more efficient, (b) searching is more efficient, or (c) body heat is lost less rapidly. 2. Otters were observed along the coast in Shetland over a 3-year period, and dives were plotted on a depth-contour map. The duration of...
Article
1. The diving behaviour of platypus (Ornithorhynchus anatinus) in their natural habitat is described, comparing performance in waters of different nutrient content. 2. The mean dive time (TUW) was 35 s, but varied between 27 s and 49 s for different habitats. These times were much longer than was predicted from comparisons with other, larger semi-a...
Article
Otters (Lutra lutra) deposit feces as scent marks (“spraints”) throughout their range, and observations on this behavior in Shetland were used to test the hypothesis that carnivores in group ranges use scent marking to signal priority of use of resources to other group members. Sprainting was seasonal (high rates coinciding with low prey availabili...
Article
Although 54% of the sample of 113 dead otters had died of non-natural causes (42% road-mortality), this figure was an artefact of the sampling method, and natural, non-violent mortality was most important. Most deaths occurred during times of low food availability (spring). Mortality increased linearly with age from year 1 onwards. Mean adult life...
Article
(1) Numbers of cubs and litters of otters (Lutra lutra L.) were analysed in relation to numbers of adults and of prey present, over a 5-year period in a study area in Shetland. Data are presented on cub mortality and its causes. (2) An estimated nine adult females in the study area produced a mean total of 5.6 litters year-1, as observed when cubs...
Article
Otters in a marine habitat selectively fished a small number of coastal sections. The densities of the relevant bottom-dwelling fish species on these feeding patches were similar to densities elsewhere, and there were no difference in the proximity of otter holts, freshwater pools or streams. It was likely that the intensive use of specific patches...
Article
The number of otter Lutra lutra dens (‘holts’) in 100 m wide strips along the coast of Shetland was estimated in a survey of a stratifiked sample of 35% of the coast. The calculated total number of holts was 1185, with 95% confidence limits of 13%. Otter holts were associated especially with peaty coasts and with fresh water. The number of otters a...
Article
Prey populations, patterns of availability, and dispersion of prey can have farreaching effects on numbers and range-sizes of terrestrial Carnivora (Macdonald, 1983; Kruuk & Parish, 1982; Kruuk & Macdonald, 1985). These parameters may therefore also affect populations of otters Lutra lutra, living in the sea around Shetland, U.K., as well as popula...
Article
The faeces (‘spraints’) of otters Lutra lutra are often used to survey populations or to indicate habitat preferences. Problems with this method are reviewed and recent criticisms of a test of the method are discussed. It is suggested that further comparisons between known otter populations and their spraint distributions are needed to test the req...
Article
Badger density was 2.2 km-2, with no significant change over 5 yr. There was a decrease in biomass of the most important food, Lumbricus terrestris, but its distribution remained the same. The size of clan territories fluctuated, but did not change significantly. There was an increase in overlap between neighbouring ranges. Every year 26% of males...
Article
Because the survey of distribution of faeces (spraints) of otters is so frequently used in the assessment of otter populations and otter habitat use, we have studied the spatial relation between sprainting and various criteria of otter activity and presence. In a marine habitat on Shetland spraints were found to be associated with otter holts and h...
Article
(1) The food of badgers was studied by analysis of faeces collected over 8 years in an area in northern Scotland. The most important food was earthworms, followed by barley. (2) During the study earthworm populations declined, and so did the badgers' consumption of worms. Barley was taken when no more oats were available, and consumption rose to a...
Article
European badgers, Meles meles, possess a large subcaudal gland which is used for scent-marking the territory and other members of the clan. It was shown experimentally that a badger can distinguish secretions from different individuals. Dominant males scent-mark most, and lactating females more than other females. Scent-marks are distributed along...
Article
Full-text available
Contents of faeces indicated that honey badgers in the Kalahari eat mostly rodents, followed by lizards and scorpions, all of which are caught by digging. Larger mammals (aardwolf, bat-eared fox, springhare) and large snakes are also eaten. Foraging behaviour is described and individual differences in foraging strategies are discussed.
Article
(1) The food of European badgers Meles meles L. is described from six areas in Scotland, using faecal analysis. The estimated relative volume of various foods in the diet is compared with the frequency of their occurrence. Variation between areas and differences between seasons are related to food availability, and the food diversity and variance o...
Article
Carnivore populations are difficult to measure by conventional methods. We have developed a new method which involves catching one or more individuals from a population and injecting them with the isotope 65 Zn. The radio-isotope appears in the faeces and assuming that the proportion of labelled to unlabelled faeces will equal the proportion of lab...
Article
(1) The earthworm Lumbricus terrestris was the predominant food of the European badger, Meles meles L. (2) In the badger's habitat, Lumbricus terrestris was most abundant under pasture. (3) Badgers caught worms on the surface at night; when feeding in grassland, their foraging efficiency was related to grass length. (4) Within their ranges, badgers...
Article
1. Food and foraging behaviour of the European badger (Meles meles L.) are described for a study area in south-central England, with the aim of understanding the biological function of badgers' spatial organisation. Animals were followed with the aid of radio-location and observed through infra-red night glasses. 2. The diet consisted largely of on...
Article
Many species of birds and mammals are attracted towards some of their natural predators, often without overt aggression. The biological function of this predator attraction was studied in a colony of herring gulls and lesser black-backed gulls, with the aid of predator models. More birds flocked above the predator model when it was presented togeth...
Article
New laboratories for the Serengeti Research Institute (Fig. 1) are about to be inaugurated by the President of Tanzania, Dr Julius Nyerere. This will be an important occasion for the study of ecology and for the future rational management of the Tanzania National Parks, and the article which follows surveys the scope of the institute's research pro...
Article
ON the Serengeti Plains and in the Ngorongoro Crater (Tanzania), the spotted hyaena is the most numerous of the large carnivores, and a study of its feeding habits is being undertaken as part of the Serengeti Research Project since it was suspected that hyaenas influenced the numbers of wildebeest (Connochaetes taurinus), zebra (Equus quagga) and T...
Article
1.1. The diurnal rhythm in the trawl catch of Solea vulgaris Quensel gave rise to this investigation into the diurnal activity rhythm of the fish.2.2. Periodicity in the food intake of the Sole in its natural habitat was studied by analyses of the contents of the intestines. Food intake appears to have a maximum during the night and a minimum durin...
Article
The Black-headed Gull removes the empty egg shell shortly after the chick has hatched. The present paper describes some experiments on the function of this response, and on the stimuli eliciting it. Carrion Crows and Herring Gulls find white eggs more readily than normal gulls' eggs; it is concluded that the natural colours of the eggs afford a cer...

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