An assessment of feral horse impacts on treeless drainage lines in the Australian Alps

The feral Horse (Equus caballus) is widespread across the Australian Alps. Feral horses degrade alpine and sub‐alpine ecosystems and damage habitat of a range of threatened species. Despite this, there is little published work to document the extent and severity of these impacts. This study investigated impacts of feral horses on treeless drainage lines at 186 sites across the Australian Alps. The study included sites in the Australian Capital Territory, New South Wales and Victoria. We assessed nine variables related to soil and stream stability and vegetation cover, which in turn influence ecosystem function and habitat quality. We found significant differences among horse‐occupied and horse‐free sites for all soil and stream stability variables assessed. For all variables assessed, the average score (and hence, condition) was worse in horse‐occupied areas. The sites in poorest condition were occupied by horses. Impacts from other mammalian herbivores species appeared to be minor. Management intervention is necessary if these impacts of feral horses are to be addressed.     

Population genetics of Great Basin feral horses

The genetic make-up of Great Basin wild (feral) horses was investigated by blood typing studies. Blood samples of 975 feral horses from seven trap sites in Nevada and Oregon were tested by serological and electrophoretic techniques for genetic markers at 19 polymorphic loci. The average number of variants for the seven feral populations [72·1 ± 3·2 (SEM), range 62–85] was not significantly different from that of 16 domestic breeds (75·0 ± 11·5, range 58–105). The expected average frequency of heterozygotes per locus (average heterozygosity) for the feral populations (0·402 ± 0·009, range 0·368–0·442) was not significantly different from the domestic breeds (0·389 ± 0·045, range 0·295–0·443). Dendrograms constructed using pairwise comparisons of Nei's distance measurements substantiated anecdotal accounts of the origins of Great Basin horses from Iberian, American saddle horse and draft horse breeds.     

Use of an ungulate‐specific feed structure as a potential tool for controlling feral goats in Australian forest ecosystems

The feral Goat (Capra hircus) has successfully exploited a range of landscapes around the world with occurrences of overabundance resulting in significant damage to ecological values. In forested ecosystems in Australia, there are currently limited means to control the species when compared to the range of management techniques available for other pest animals. To redress this deficiency, we designed a feed structure combined with commercially available salt blocks to attract goats to set locations in a forested study area. Structures that exploited differences in the pedal morphology (foot size and shape) of native herbivores (kangaroos and wallabies) and ungulates (feral goats and deer) were found to be highly target‐specific, with feral goats freely able to access salt blocks, whilst nontarget native species were effectively excluded. Other introduced ungulate species, Fallow Deer (Dama dama) and Red Deer (Cervus elaphus), successfully accessed salt blocks in feed structures but at a considerably lower rate than feral goats. The capacity to present a range of bait types within a target‐specific feed structure, once matched with a humane toxicant, could provide land managers with an additional cost‐effective lethal control tool for future management of feral ungulates, particularly goats.     

Modelling horse management in the Australian Alps

Management of the feral Horse (Equus caballus) in the Australian Alps bioregion is a difficult and emotive issue, with interested parties working from vastly differing perspectives. Compounding this, information regarding ecology and distribution of horses, and the cost and effectiveness of management strategies is often unknown or uncertain. Resolving these issues requires an objective approach with the flexibility to incorporate different potential scenarios. We used a spatially explicit population model to compare the potential effects of two different management strategies on populations of horses in the Australian Alps bioregion: culling from helicopters versus trapping and mustering. We populated the model using the results of population surveys conducted in 2014, vegetation data and cost estimates. We then provided an estimate of the effect of each strategy on population size across the Alps, and their corresponding costs, compared to no management. To account for uncertainties, we simulated different scenarios for horse population densities, dispersal rates and population growth rates. Management using aerial culling was more effective than mustering in every scenario modelled, and three to six times cheaper. Aerial culling was only slightly more effective within its control region. However, because mustering is necessarily restricted by road access, this translated to a substantial improvement in population control – up to 2000 horses where growth and dispersal rates were high. Our results unequivocally suggest aerial culling as the only strategy that could effectively control horses within the modelled range of scenarios; this result stands in addition to its other potential benefits of lower cost, animal stress and landscape disturbance. A major advantage of this modelling approach is that we can easily update it with new data, test different measures of effectiveness and add new scenarios to adapt to the rapidly changing situation on the ground, both in terms of the ecology and the political climate.     

Impacts of feral horses and deer on an endangered woodland of Kosciuszko National Park

In recent years, the impacts of rapidly increasing populations of feral horses and deer on the vegetation and stability of soils have become highly visible and widespread in Kosciuszko National Park. We investigated these impacts in the White Cypress Pine (Callitris glaucophylla Joy Thomps. & L.A.S. Johnson) – White Box (Eucalyptus albens Benth) woodlands of the lower Snowy River valley. This woodland is a component of the White Box‐Yellow Box‐Blakely's Red Gum Grassy Woodland and Derived Native Grasslands complex that is nationally listed as a critically endangered ecological community. To investigate the severity of the impacts of feral horse (Equus caballus) and deer (Dama dama and Rusa unicolor) in the valley in 2013 and 2017/18, we surveyed fenced exclosures and paired grazed plots that were first established and surveyed in 1984 and re‐surveyed in 1987. Using LFA and VAST methodologies (not used in 1987), we compared the relative response of environmental variables in plots inside and outside the exclosures in an attempt to ascertain recent herbivore impacts. While there was no evidence of horses or deer from dung surveys in 1987, in 2018, 84% of the dung was from horses, 13% from deer, 1% from rabbits and 2% from macropods. Total herbivore dung density increased fourfold since the 1987 survey. On the understanding that all plots had the same starting condition in 1984 with respect to prior herbivory, we deduce that horses and deer are having significant ecological impacts. There was a far greater cover of understorey plants and the midstorey was denser and taller inside the exclosures. Outside the exclosures, the vegetation cover was far more sparse and soil erosion was active and extensive. The total number of invertebrates captured in small pitfall traps was nearly twice as many within the exclosures compared to the grazed plots. The dense even‐aged regrowth overstorey stands of White Cypress Pine, inside and outside the exclosures, have changed little in 34 years.     

A contribution to the D system in horses*

The inheritance of a new D system red cell antigen, factor 22, is described. It has also been possible to discriminate more efficiently between D system pheno-groups enabling genotypes to be identified from phenotypes in the majority of cases. This improves the accuracy of animal identification and gene frequency estimates.     

Rapid morphological change in an insular population of feral sheep

Artificially selected qualities can reduce fitness in a wild setting, thus feral domesticates should experience strong selective forces. Domestic sheep Ovis aries have frequently become feral on islands, which differ substantially from mainland environments. We examined changes in body mass and wool traits in feral sheep inhabiting Santa Cruz Island (SCI), California for ≥90 years. To elucidate the influence of nutrition, we compared the mass of feral island sheep with that of island sheep raised in farm conditions. We found that feral sheep on SCI were smaller than purported founder breeds, and that most documented populations of insular feral sheep worldwide have converged to similar body sizes (within 6 kg). SCI rams attained greater mass in farm conditions but ewes did not, suggesting phenotypic plasticity in ram body mass. Ewes exhibited self-shedding of wool at a greater frequency than rams, and sex differences and shedding patterns were consistent with thermoregulation and the risk of fly strike disease as benefits of wool loss. Pigmentation rates did not increase, further supporting the influence of heat stress on wool traits. These changes occurred in <25 generations and may have had a genetic basis, representing a potential example of rapid evolution in insular feral sheep.     

Aggressive behaviour in the skyhoppers of the Australian Alps

Evolutionary Ecology - The evolution of male-male aggression is of interest because at its extreme it can be very energetically costly, leave males vulnerable to preadtors, and give rise to...     

Direct evidence implicates feral cat predation as the primary cause of failure of a mammal reintroduction programme

As evidence mounts that the feral Cat (Felis catus) is a significant threat to endemic Australian biodiversity and impedes reintroduction attempts, uncertainty remains about the impact a residual population of cats following control will have on a mammal reintroduction programme. Also, behavioural interactions between cats and their prey continue to be an area of interest. Within the framework of an ecosystem restoration project, we tested the hypotheses that successful reintroductions of some medium‐sized mammals are possible in locations where feral cats are controlled (but not eradicated) in the absence of European Red Fox (Vulpes vulpes), and that hare‐wallabies that dispersed from their release area are more vulnerable to cat predation compared with those that remain at the release site. We used radiotelemetry to monitor the survivorship and dispersal of 16 Rufous Hare‐wallabies (Lagorchestes hirsutus spp.) and 18 Banded Hare‐wallabies (Lagostrophus fasciatus fasciatus) reintroduced to four sites within Shark Bay, Western Australia. Nearly all foxes were removed and feral cats were subject to ongoing control that kept their indices low relative to prerelease levels. All monitored hare‐wallabies were killed by cats within eight and 10 months following release. Significant predation by feral cats was not immediate: most kills occurred in clusters, with periods of several months where no mortalities occurred. Once a hare‐wallaby was killed, however, predation continued until each population was eliminated. Animals remaining near their release site survived longer than those that dispersed. The aetiology of predation events observed offers new insights into patterns of feral cat behaviour and mammal releases. We propose a hypothesis that these intense per capita predation events may reflect a targeted hunting behaviour in individual feral cats. Even where feral cats are controlled, the outcome from consistent predation events will result in reintroduction failures. Managers considering the reintroduction of medium‐sized mammals in the presence of feral cats should, irrespective of concurrent cat control, consider the low probability of success. We advocate alternative approaches to cat‐baiting alone for the recovery of cat‐vulnerable mammals such as hare‐wallabies.     

A new view on dam lines in Polish Arabian horses based on mtDNA analysis

Polish Arabian horses are one of the oldest and the most important Arab populations in the world. The Polish Arabian Stud Book and the Genealogical Charts by Skorkowski are the main sources of information on the ancestors of Polish Arabs. Both publications were viewed as credible sources of information until the 1990s when the data regarding one of the dam lines was questioned. The aim of the current study was to check the accuracy of the pedigree data of Polish dam lines using mtDNA analysis. The analyses of a 458 bp mtDNA D-loop fragment from representatives of 15 Polish Arabian dam lines revealed 14 distinct haplotypes. The results were inconsistent with pedigree data in the case of two lines. A detailed analysis of the historical sources was performed to explain these discrepancies. Our study revealed that representatives of different lines shared the same haplotypes. We also noted a genetic identity between some lines founded by Polish mares of unknown origin and lines established by desert-bred mares.     

Self‐stigma and the “why try” effect: impact on life goals and evidence‐based practices

Many individuals with mental illnesses are troubled by self-stigma and the subsequent processes that accompany this stigma: low self-esteem and self-efficacy. “Why try” is the overarching phenomenon of interest here, encompassing self-stigma, mediating processes, and their effect on goal-related behavior. In this paper, the literature that explains “why try” is reviewed, with special focus on social psychological models. Self-stigma comprises three steps: awareness of the stereotype, agreement with it, and applying it to one’s self. As a result of these processes, people suffer reduced self-esteem and self-efficacy. People are dissuaded from pursuing the kind of opportunities that are fundamental to achieving life goals because of diminished self-esteem and self-efficacy. People may also avoid accessing and using evidence-based practices that help achieve these goals. The effects of self-stigma and the “why try” effect can be diminished by services that promote consumer empowerment.     

Plant invasions in treeless vegetation of the Australian Alps

A total of 128 invasive plant species have been recorded in treeless vegetation in the Australian Alps. Most of these are forbs and most are uncommon. Cover of invasive species is generally minimal unless there has been gross disturbance to natural vegetation and soils. Although there is a significantly positive correlation between invasive and native species diversity, suggesting that conditions that allow numerous native species to co-exist also permit more plant invasions, altitude is the most important determinant of invasive species diversity. Only 22 of the 128 species have been recorded above 1800 m. Some plant communities (e.g. those with high pH or relatively nutrient-rich soils), however, seem to be vulnerable to invasions regardless of altitude. Most invasive species appear to have been introduced unintentionally (e.g. as seed attached to vehicles, animals and humans) but a few were introduced to assist with revegetation of disturbed soils and for amenity plantings in ski resorts, and have subsequently established in native vegetation. Treeless communities in the Australian Alps are likely to face increasing pressure from invasive species as a result of global warming and continued introduction of non-native plants to ski resort gardens. Whilst it may be difficult to prevent invasive species of low elevations migrating to higher elevations as temperatures rise, the risk of invasion from garden plants could be minimised through regulation. Non-native plants in ski resort gardens pose a far greater risk than most invasive species currently present in the Alps because they have been chosen for their capacity to survive at high altitudes.     

Transferrin gene frequencies of feral and domestic goats in New Zealand

Abstract

Blood plasma from three populations of feral goats (Capra hircus L.) and from five domestic breeds was analysed by polyacrylamide gel electrophoresis. The albumin locus was monomorphic in all samples. The macroglobulin locus was variable but lacked resolution on the gel. The transferrin (Tf) locus was polymorphic. The only two Tf alleles observed (Tf A and Tf B) did not vary from those described by other authors. Gene frequencies of the two Tf alleles showed that one feral population could be distinguished from the other two. Gene frequencies of domestic breeds were variable and showed no definitive pattern. Domestic breed type could not be recognised in the feral populations on the basis of transferrin analysis alone.     

Prevalence of yeast-like fungi and evaluation of several virulence factors from feral pigeons in Seoul, Korea

Aims: Studies of pigeon‐borne yeasts have tended to focus on species, such as Cryptococcus neoformans and Candida albicans, with scant attention to feral pigeons in Korea. We studied the prevalence of yeasts from faecal samples of feral pigeons obtained in various public places in Seoul, Korea, and assessed their potential capacity as human pathogens. Methods and Results: Three hundred and six pigeon faeces samples were collected at city squares and parks in 21 localities in Seoul and Seoul Grand Park and analysed for yeast with conventional methods. Of the 306 samples, 126 (41·2%) were positive for yeast. Seventeen species of yeast were identified. The most frequent species were Candida glabrata (34·1%), Candida famata (12·7%), Cryptococcus albidus (14·3%) and Cryptococcus laurentii (7·9%). The yeast isolates were tested for virulence. Of the 116 isolates (ten isolates missing), 70·7% (n = 82) grew at 37°C. All the Cryptococcus spp. isolates possessed a capsule, 16·4% (n = 19) produced melanin, and 33·6% (n = 39) produced proteinase. Two Ca. glabrata, a Ca. famata and Ca. albicans as well as three C. neoformans, a C. laurentii and Ca. albicans isolates had three virulence factors. Accordingly, 29·3% (n = 34) isolates possessed more than two virulence factors except capsule formation. Conclusions: These results of this study indicate that feral pigeons harbour a variety of yeasts and are a reservoir of human pathogenic fungi. Significance and Impact of the Study: This study is the first time about the microflora (fungi) presents in faecal samples collected from a variety of public areas throughout Seoul, Korea.     

Linking genetic diversity and temporal fluctuations in population abundance of the introduced feral cat (Felis silvestris catus) on the Kerguelen archipelago

Linking temporal variations of genetic diversity, including allelic richness and heterozygosity, and spatio-temporal fluctuations in population abundance has emerged as an important tool for understanding demographic and evolutionary processes in natural populations. This so-called genetic monitoring was conducted across 12 consecutive years (1996-2007) at three sites for the feral cat, introduced onto the Kerguelen archipelago fifty years ago. Temporal changes in allelic richness and heterozygosity at 18 microsatellite DNA loci were compared with temporal changes in the adult population abundance index, obtained by typical demographic monitoring. No association was found at the island spatial scale, but we observed an association between genetic diversity and adult population indices from year to year within each study site. More particularly, the magnitude of successive increases or decreases in the adult population abundance index appeared to be the major factor linking the trajectories of genetic diversity and adult population abundance indices. Natal dispersal and/or local recruitment, both facilitated by high juvenile survival when the adult population size is small, is proposed as the major demographic processes contributing to such an observed pattern. Finally, we suggested avoiding the use of the harmonic mean as an estimator of long-term population size to study the relationships between demographic fluctuations and heterozygosity in populations characterized by strong multiannual density fluctuations.     

Genetic relationships between breeds of horses and ponies in the Netherlands

An investigation on the genetic relationships between 12 horse and pony breeds was performed, using blood protein variants as genetic markers. The relationships were established by the use of 5 different numerical taxonomic methods, 4 of which yielded very similar results. The relationships as estimated were evaluated on the basis of the breeds' historical development.     

Eumelanin‐based colouration reflects local survival of juvenile feral pigeons in an urban pigeon house

Urbanisation introduces deep changes in habitats, eventually creating new urban ecosystems where ecological functions are driven by human activities. The higher frequency of some phenotypes in urban vs rural/wild areas has led to the assumption that directional selection in urban habitats occurs, which may thereby favour some behavioural and physiological traits in urban animal populations compared to rural ones. However, empirical evidence of directional selection on phenotypic traits in urban areas remains scarce. In this study we tested whether eumelanin‐based colouration could be linked to survival in two urban populations of the feral pigeon Columba livia. A number of studies in different cities pointed out a higher frequency of darker individuals in more urbanised areas compared to rural ones. To investigate whether directional selection through survival on this highly heritable trait could explain such patterns, we conducted mark–recapture studies on two populations of feral pigeons in highly urbanized areas. We predicted that darker coloured individuals would exhibit higher survival and/or philopatry (integrated into ‘local survival’) than paler coloured ones. No difference in local survival was found between adults of different colouration intensities. However, on one site, we found that darker juveniles had a higher local survival probability than light ones. Juvenile local survival on that site was also negatively correlated with the number of chicks born. This suggests the existence of colour‐ and/or density‐dependent selection processes acting on juvenile feral pigeons in urban environments, acting through differential mortality and/or dispersal.     

Community response to transgenic plant release: predictions from British experience of invasive plants and feral crop plants

The ten-ten rule can be used to predict the community consequences of releasing GMOs. This, combined with data on the feral state of British crop plants, predicts that almost all GMOs will become at least casual, that more than 10% will establish, and about 10% of those will become pests. Which constructs will fall into which category cannot be predicted from their characters. In particular, Baker characters have no predictive value for weediness. The fourteen most troublesome invasive plant pests show a remarkably diverse set of characters. GMOs, being mainly derived from crop plants, and in some cases with genes that are likely to enhance survival, can be expected to have an appreciable effect on nonagricultural ecosystems, once a range of different constructs have been released. Familiarity is unlikely to be an effective defence against new ecological effects.     

Linkage disequilibrium between the ELA and the A blood group systems in Standardbred horses

The linkage group formed by the ELA and A blood group system in horses was studied in American Standardbred horses. The distance between the ELA locus and the A blood group locus was measured as 1.61 centimorgans. observing only the haplotypes contributed by the sires.
Strong linkage disequilibrium was found in pacing Standardbred horses for ELA-W1 with Aa, ELA-W5 with Ab and ELA-W10 with Ab. Linkage disequilibrium was apparent at both the population and family level. Among trotting Standardbred horses, linkage disequilibrium was found for ELA-W1 with Aa and for ELA-W10 with Ab. It was not possible to investigate linkage relationships in Thoroughbred horses because of the high frequency of Aa and low frequency of other A system markers.     

Genetic structure of populations of horses based on distribution of hemotypes

The distribution of hemotypes, that is, the juxtaposition of electrophoretic phenotypes at six blood protein and enzyme loci expressing the individual genetic traits of every member of a population, has been investigated in 15 populations belonging to nine breeds of horses. The total number of hemotypes recorded in a population was lower than the number expected on the basis of allelic frequencies. The mean number of individuals per hemotype varied from 1.5 in ponies to 18.6 in Thoroughbreds. Breeds or populations differ either qualitatively by the nature of hemotypes, or quantitatively by the proportions of repetitive hemotypes carried by several individuals, and of unique hemotypes, carried by single individuals. The so-called closed breeds of populations, such as Thoroughbreds, contain predominantly repetitive hemotypes, while the feral or rustic breeds present a large proportion of unique hemotypes.