Urban domestic gardens (II): experimental tests of methods for increasing biodiversity

The extent and continued expansion of urbanisation has focused attention on the significance for native biodiversity of those green spaces remaining within such areas and the most appropriate methods of managing them. In the UK, a high proportion of urban space is comprised of the private or domestic gardens associated with residential dwellings, and many recommendations have been made for simple changes to improve their value for biodiversity (wildlife gardening). Here, we report the results of replicated experimental tests of five such common recommendations, involving the introduction to gardens of (i) artificial nest sites for solitary bees and wasps; (ii) artificial nest sites for bumblebees; (iii) small ponds; (iv) dead wood for fungi and other saproxylic organisms; and (v) patches of nettles Urtica dioica L. for butterfly larvae. The broad conclusion is that whilst some methods for increasing the biodiversity of garden environments may be very effective, others have a low probability of success on the timescales and spatial scales likely to be acceptable to many garden owners. If one of the functions of small scale biodiversity enhancement is to develop and encourage awareness of biodiversity and its conservation, then encouragement to conduct particular activities must be balanced with a realistic appraisal of their likely success.     

Urban Domestic Gardens (IV): The Extent of the Resource and its Associated Features

Domestic (‘private’) gardens constitute a substantial proportion of ‘green space’ in urban areas and hence are of potential significance for the maintenance of biodiversity in such areas. However, the size and nature of this resource and its associated features are poorly known. In this study, we provide the first detailed audit, using domestic gardens in the city of Sheffield as a model study system. Domestic gardens, the mean area of which was 151 m², cover approximately 33 km² or 23% of the predominantly urban area of the city. The smaller gardens contribute disproportionately to this total because, although individually they add little, they are large in number. Conversely, the regions of the city with proportionately more garden area contribute most to the total garden area of the city, although such regions are limited in number. Based on the findings of a telephone based survey, 14.4% of dwellings with gardens were estimated to have ponds, 26% to have nest-boxes, 29% to have compost heaps, 48% to hold trees more than 3 m tall, and 14% of dwellings were estimated to be home to one or more cats. Whilst the absolute frequency of these features is low to moderate, by extrapolation they nonetheless yield estimates for domestic gardens in Sheffield of a total of 25,200 ponds, 45,500 nest boxes, 50,750 compost heaps, 360,000 trees, and a population of 52,000 domestic cats. These results are considered in the context of the role of gardens in urban areas as habitats for wildlife and the implications for housing policy.     

Urban domestic gardens (VIII) : environmental correlates of invertebrate abundance

Domestic gardens associated with residential zones form a major component of vegetated land in towns and cities. Such gardens may play a vital role in maintaining biodiversity in urban areas, but variation in the abundance of organisms in gardens has been little explored. We report the results from a case study of 61 domestic gardens in the city of Sheffield, UK. Across 22 invertebrate groups, the median number of individuals recorded per garden was 49, 178, and 1012 in litter collections, pitfall and Malaise trap samples, respectively. Abundance was analysed by stepwise multiple regression and hierarchical tree analysis in relation to garden and landscape variables. The amount of variation explained in regression models ranged from 4 to 56%, for data based on pitfall and litter samples, and from 16 to 92% for data from Malaise traps. In total, 31 out of 36 explanatory variables entered into stepwise regression models, and 29 of them did so more than once. Although there was strong evidence only for approximately half of such relationships, in these cases the two methods of analysis corroborated one another. General correlates of invertebrate abundance were lacking, and likely reasons for inconsistencies in the relationships are discussed in the context of sampling and species biology. Correlates of the greatest significance occurred at both landscape (e.g. altitude) and garden scales (e.g. area of canopy vegetation). These factors were associated with species richness as well as abundance.     

Urban domestic gardens (VI): environmental correlates of invertebrate species richness

Domestic gardens associated with residential zones form a major component of undeveloped land in towns and cities. Such gardens may play a vital role in maintaining biodiversity in urban areas, but explanations for the variation in the richness of species assemblages in gardens are lacking. We report the results from a case study of 12 invertebrate groups in 61 domestic gardens in the city of Sheffield, UK. The mean number of species within a taxon, recorded per garden, was no greater than 3, 10, and 20 species in litter, pitfall trap and Malaise trap samples, respectively. Relatively speciose groups exhibited high turnover between gardens, with typically 50% of the group occurring only once. In contrast, several species-poor taxa were virtually ubiquitous. Species richness was analysed by multiple regression and hierarchical tree analysis in relation to garden and landscape variables. In general, the two methods of analysis corroborated one another. In total, 22 explanatory variables entered into regression models, although 12 of them only did so once. The amount of variation in species richness explained in models was generally quite high, with the factors involved operating over a range of scales. However, the patterns that emerged were not consistent across taxa. The most important predictors of species richness, of relevance to land use planners, were components of garden vegetation, especially the abundance of trees. Likely reasons for inconsistencies in the relationships are discussed in the context of sampling and species biology.     

Communication between domestic dogs (Canis familiaris) and humans: Dogs are good learners

Communication involves a wide range of behaviours that animals emit in their daily lives and can take place between different species, as is the case of domestic dogs (Canis familiaris) and humans. Dogs have shown to be successful at following human cues to solve the object choice task. The question is what are the mechanisms involved in these communicative abilities. This article presents a review of studies about the communicative capacities of domestic dogs emphasizing the ones that considered the effect of associative learning upon these skills. In addition, evidence about differences in dogs’ performance in following physical or social cues is summarized and two studies where both signals compete are presented here. The obtained results suggest that the training of a colour cue reverses the dogs’ preference for the social one. These results are discussed in light of the findings that gave importance to the learning effect, concluding that the dogs fundamentally follow those cues that allowed them to obtain reinforcers in their previous learning history.     

Male reproductive success in the domestic cat (Felis catus L.): A case history

The domestic cat shows a great variability in different life history traits like its social organization, ranging from a solitary life to living in large social groups depending on environmental conditions. Until now, the mating system has not been shown to vary between populations and was described as promiscuous. Here we present data on the reproductive success of a male, which clearly show that monopolization of females by males is possible in this species.     

Thyrotropin-releasing hormone (TRH)-immunoreactive structures in the brain of the domestic mallard

Summary The distribution of immunoreactive thyrotropin-releasing hormone (TRH) in the central nervous system of the domestic mallard was studied by means of the peroxidase-antiperoxidase technique. After colchicine pretreatment, the highest number of TRH-immunoreactive perikarya was found in the parvocellular subdivision of the paraventricular nucleus and in the preoptic region; a smaller number of immunostained perikarya was observed in the lateral hypothalamic area and in the posterior medial hypothalamic nucleus. TRH-immunoreactive nerve fibers were detected throughout the hypothalamus, forming a dense network in the periventricular area, paraventricular nucleus, preoptic-suprachiasmatic region, and baso-lateral hypothalamic area. TRH-containing nerve fibers and terminals occurred in the organon vasculosum of the lamina terminalis and in the external zone of the median eminence in juxtaposition with hypophyseal portal vessels. Scattered fibers were also seen in the internal zone of the median eminence and in the rostral portion of the neural lobe. Numerous TRH-immunoreactive fibers were detected in extra-hypothalamic brain regions: the highest number of immunoreactive nerve fibers was found in the lateral septum, nucleus accumbens, olfactory tubercle, and parolfactory lobe. Moderate numbers of fibers were located in the basal forebrain, dorsomedial thalamic nuclei, hippocampus, interpeduncular nucleus, and the central gray of the mesencephalon. The present findings suggest that TRH may be involved in hypophysiotropic regulatory mechanisms and, in addition, may also act as neuromodulator or neurotransmitter in other regions of the avian brain.     

The social function of tail up in the domestic cat (Felis silvestris catus)

We investigated the social function of tail up in order to verify its possible relationship with the hierarchical organization of a social group. Domestic cats live at higher densities than their ancestor which is a solitary species. Since the signals needed by solitary animals have different properties than those needed by group-living individuals, signalling pattern utilised by the domestic cat has inevitably changed. Kittens displayed the tail up when greeting their mother; this behaviour can also be observed in wild species. But, in domestic cat the tail up can be also observed when an adult individual meets another one and it signals the intention to interact amicably. Rank order affected the display of tail up posture: it was more frequently displayed by low-ranking cats, and high-ranking individuals received it more often than other members of the social group. Then, tail up seems to be a signal by means of which a cat shows the recognition of the higher social status of the individual to whom is directed. We confirmed the association between tail up and other affiliative behavioural patterns and the individual variability in displaying them. Considerations on the evolution of the tail up as a visual signal will be discussed.     

Navigational ability in the domestic fowl (Gallus gallus domesticus)

Little is known about the navigational abilities of domestic fowl. The question of how chickens represent and orient in space becomes relevant when they are kept in non-cage systems. Since the sun is known to be the dominant spatial organiser in other diurnal bird species, we started our investigation of the chicken’s spatial abilities by subjecting them to a food-searching task with the sun as the only consistent visual cue. In an additional experiment we tried to rule out the use of auditory cues in finding a food reward.

Eight ISA Brown chicks were housed in outdoor pens. A separate test arena comprised an open-topped, opaque-sided wooden octagon (2 m wide and 1.5 m high). Eight goal boxes with food pots were attached to each of the arena sides; a wooden barrier inside each goal box prevented the birds from seeing the food pot before entering. After habituation we tested during five daily 5 min trials whether the chicks were able to find food in a systematically allocated goal direction. Food residue in every foot pot controlled for the use of olfactory cues and no external landmark cues were visible. Every day each box was unpredictably moved to a randomly assigned side of the arena and the side to face north was also randomly allocated, to prevent the chicks from using cues other than the sun’s position. Circular statistics were used to determine whether birds moved in a non-random direction and if so, if they significantly oriented goalwards. The results showed that seven of the eight birds moved significantly in the goal direction. It seems likely that the chicks used the sun to orient. Due to weather constraints only four chicks received the same treatment on a new location, to rule out the use of auditory cues. Two of these four chicks significantly moved in the goal direction.

The results from our experiments show that domestic chicks use spatial memory to orient towards a hidden goal. Moreover, their orientation is most likely to be based on sun cues opening up the possibility that the sun compass may dominate even in this ancestrally predominantly ground-living forest bird.     

Successful city dwellers: a comparative study of the ecological characteristics of urban birds in the Western Palearctic

Numerous species have adapted to the proximity of humans, and this feature is no clearer than among species that have invaded towns and cities. The characteristics of species that have successfully managed to expand their range into urban areas remain largely unexplored, although they are of general interest in a world that is increasingly urbanised. I hypothesised that widely distributed species with high dispersal abilities, species with a high rate of innovation, a high level of risk-taking, and a fast life history would have a selective advantage in habitats influenced by humans. Consistent with this hypothesis, in a comparative analysis of 39 independent evolutionary events of urbanisation of birds in the Western Palearctic (thus taking the fact that closely related species that have become urbanised are caused by common phylogenetic descent rather than convergent evolution), bird species that adapted to urban habitats were characterised by large breeding ranges, high propensity for dispersal, high rates of feeding innovation (novel ways of acquiring food), short flight distances when approached by a human, and a life history characterised by high annual fecundity and high adult survival rate. Urban species may be disproportionately resistant to parasitism and predation because they had disproportionately strong immune responses, as reflected by the size of the bursa of Fabricius, and a history of weak predation-mediated natural selection, as reflected by the force required to remove feathers from the rump. Urban species had high overall ecological success as indicated by large range size and population size and high population density. This suggests that a suite of ecological features providing them with general ecological success characterises species of birds that have successfully invaded urban environments. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Immunohistochemical localization of the luteinizing hormone releasing hormone (LHRH)-containing structures in the central nervous system of the domestic fowl

Summary The location of LHRH-containing neuronal elements was investigated in the domestic fowl by means of immunohistochemical techniques. LHRH antisera were raised against synthetic LHRH in the rabbit. The antiserum used in the present study cross-reacted with LHRH of mammalian and avian tissues.LHRH-immunoreactive perikarya are located in the preoptic and in the septal areas, and in the bulbus olfactorius; however, no LHRH-immuno-reactive perikarya were found in the tuberal part of the hypothalamus. LHRH-immunoreactive fibers course from these areas toward the median eminence mainly along the wall of the third ventricle in the form of a periventricular network. Originating from the same cell groups other fibers run caudally immediately above the optic chiasma, forming the median bundle of the tractus preoptico-infundibularis. The third bundle running toward the OVLT is named the tractus preoptico-terminalis. In addition to these structures, LHRH-containing fibers and terminals were also present in different regions of the limbic system, in the dorsal part of the hippocampus, in the tuberculum and bulbus olfactorius, as well as in the optic lobe, nuclei commissurales tectales, organon subcommissurale, periaqueductal area, and pars ventralis mesencephali.The general distribution of the LHRH system in the chicken corresponds principally to that described previously in rodents (Sétáló et al. 1976, 1978). However, some subtle differences were demonstrated between the location of the LHRH system in birds and mammals.     

Conservation management of Gortyna borelii lunata (Lepidoptera: Noctuidae) in the United Kingdom

Gortyna borelii lunata is a rare species of moth with a widespread, but localised distribution in Europe. In Britain, the moth is restricted to coastal grassland habitats that support its larval foodplant (Peucedanum officinale), in the southeast of England.Threats to G. borelii lunata in Britain include inappropriate management and sea-level rise. This study investigates how to secure the future of the moth in Britain by managing existing colonies appropriately and determining whether translocations of the species, away from the dangers of flooding, would be feasible. A mowing experiment and a translocation trial were conducted. Results from the mowing experiment indicate that cutting annually in either August or November is detrimental to the abundance of the moth. It is recommended that where sites must be mown this be performed on rotation, leaving much of the site uncut each year. The translocation of the moth and its foodplant to a site away from the threats of flooding was very successful, demonstrating that the species establishes well and can survive on higher ground. It is concluded that to secure the future of the moth in Britain, a sustainable network of interconnected sites for the species should be created. Also, an appropriate management plan should be formulated for each site.     

Morphological variation in the Chamaecytisus proliferus (L.f.) Link complex (Fabaceae: Genisteae) in the Canary Islands

FRANCISCO-ORTEGA, J., JACKSON, M. T., SANTOS-GUERRA, A. & FORD-LLOYD, B. V., 1993. Morphological variation in the Chamaecytisus proliferus (L.f.) Link complex (Fabaceae: Genisteae) in the Canary Islands . A multivariate study (Principal Component Analysis and Cluster Analysis, Warďs method) of 47 morphological traits from 164 populations of Chamaecytisus proliferus (L.f.) Link from the Canary Islands confirmed that this species complex is formed by seven morphological types. At least eight traits discriminated between these types. Patterns of variation follow a cline within Gran Canaria, Tenerife and La Palma. These results also show that morphological variation is greater in the eastern islands (i.e. Gran Canaria and Tenerife) than in the western islands (La Gomera, El Hierro and La Palma) and that no morphological differences are found between plants of typical tagasaste from wild and cultivated populations.     

Oral disease in free-living red squirrels (Sciurus vulgaris) in the United Kingdom

Ninety-one red squirrels (Sciurus vulgaris) found dead in the UK between January 1994 and August 1998 were necropsied at the Institute of Zoology (London, UK); their oral cavities were examined visually, and in eight cases, radiographically. Four red squirrels, which had evidence of oral disease when necropsied as part of a mortality survey, also were examined. A low prevalence (prevalence = 0.033, SE = 0.02, n = 91) of oral disease was found in free-living red squirrels. In only two cases was oral disease the probable cause of death. Attrition of the check teeth (three cases) and overgrowth of the incisors (four cases) were the most common lesions found. Partial anodontia was recorded in one squirrel.     

Effect of reinforcement, reinforcer omission and extinction on a communicative response in domestic dogs (Canis familiaris)

There is a controversy about the mechanisms involved in the interspecific communicative behaviour in domestic dogs. The main question is whether this behaviour is a result of instrumental learning or higher cognitive skills are required. The present investigations were undertaken to study the effect of learning processes upon the gaze towards the human's face as a communicative response. To such purpose, in Study 1, gaze response was subjected to three types of reinforcement schedules: differential reinforcement, reinforcer omission, and extinction in a situation of “asking for food”. Results showed a significant increase in gaze duration in the differential reinforcement phase and a significant decrease in both the omission and extinction phases. These changes were quite rapid, since they occurred only after three training trials in each phase. Furthermore, extinction resulted in animal behaviour changes, such as an increase in the distance from the experimenter, the back position and lying behaviour. This is the first systematic evaluation of the behavioural changes caused by reward withdrawal (frustration) in dogs. In Study 2, the gaze response was studied in a situation where dogs walked along with their owners/trainers. These results show that learning plays an important role in this communicative response. The possible implications of these results for service dogs are discussed.     

Genetic variation in Bromus tectorum (Poaceae): differentiation in the eastern United States

Bromus tectorum, a devastating plant invader in western North America, had entered Pennsylvania by 1790. Although rare, or extirpated, in the east until the 1850s, it was collected with increasing frequency after 1859 from Vermont to Virginia. Using enzyme electrophoresis, we analyzed 38 populations of this grass in the eastern U.S. to determine their genetic variation and structure as well as assess their relatedness to populations in the west. Genetic variation among eastern U.S. populations is low: mean number of alleles per locus (A), percent polymorphic loci per population (%P), and expected heterozygosity (H(exp)) are 1.01, 1.05%, and 0.002, respectively. No heterozygotes were detected. The eastern populations are genetically similar: mean genetic identity for all populations was 0.990 with values among population pairs ranged from 0.913 to 1.000. Thirteen populations in eastern and western North America shared Pgm-1a and Pgm-2a, while eight populations shared Mdh-2b and Mdh-3b. Other alleles detected in western North America (Got-4c, Got-4d, and Pgi-2b) were not, however, found in eastern U.S. populations. The invasion of North America by B. tectorum occurred through multiple introductions on both coasts; results from historical and genetic evidence suggest that eastern populations stem from a minimum of two introductions. The 19th century westward spread of B. tectorum from the East appears to be plausible.     

Naturally occurring Sarcocystis infection in domestic cats (Felis catus)

Equine protozoal myeloencephalitis is an important neurological disease of horses in the United States. Consequently, there is an active research effort to identify hosts associated with the primary causative agent, Sarcocystis neurona. The purpose of this study was to determine whether the domestic cat (Felis catus) is a natural host for S. neurona. Muscle sections from 50 primarily free-roaming domestic cats were examined for the presence of sarcocysts. Serum from cats in this group and another group of 50 free-roaming cats were evaluated for the presence of S. neurona antibody. Sarcocysts were found in five of 50 (10%) cats, and S. neurona antibody in five of 100 (5%) cats. Morphological, molecular (including ribosomal RNA genes), and biological characterisation of these sarcocysts showed that they were not S. neurona or S. neurona-like. Sarcocysts found in the cats were identified morphologically as Sarcocystis felis, a common parasite of wild felids. The life cycle of S. felis is not known, and prior to this study, no molecular marker for S. felis existed. Although cats were found to be infected with S. felis sarcocysts, serological data provided evidence of possible infection with S. neurona as well. Further work is needed to determine the role of the domestic cat in the life cycle of S. neurona.     

Seroepidemiology of rabbit haemorrhagic disease (RHD) in wild rabbits (Oryctolagus cuniculus) in the United Kingdom

An extensive collection of blood samples from adult wild rabbits, from areas where Rabbit Haemorrhagic Disease (RHD) had not been recorded, was obtained from sites across the U.K. and parts of Eire over the winter of 1994/95. Sera from 946 animals were examined for antibodies to RHD. Antibody was found in all populations, varying between 20 and 100% depending on locality, and overall 64% of rabbits were seropositive in midwinter, supporting the view that non-pathogenic RHD or RHD-like caliciviruses, which are not producing clinical disease, circulate within rabbit populations. The serological response to these agents appears to confer significant immunity on rabbits subsequently exposed to the virulent RHD virus, so the disease will not be as devastating as myxomatosis was in the early 1950s (99% mortality) but at least one-third of the c. 40 million rabbits in the U.K. are susceptible.