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Conservation, disease, education, grey squirrel, invasive, nature, red squirrel, UK, wildlife
The red squirrel (Sciurus vulgaris) is native to the UK and could historically be found in both coniferous and deciduous woodlands, though it is now almost exclusively found in the former. It is primarily an arboreal species, feeding on a range of seeds and nuts during the warmer months before spending much of the winter in a state of torpor. Populations of S. vulgaris have declined markedly across most the UK since the 1930’s with current population estimates hovering around 160,000. Around 75% of these occur in Scotland with the other 25% being found in isolated patches throughout England and Wales. The reasons for this decline are threefold: i) extensive fragmentation and loss of suitable habitat, ii) inter-specific competition with and iii) transmission of the parapox virus from the introduced North American grey squirrel (S. caroliniensis) which now numbers in the region of 2.5 million.
A survey carried out in Northern Ireland on red and grey squirrel habitat associations showed a specific distinction in preference between species for coniferous or deciduous forests. Red squirrels occupied predominantly large coniferous forests at higher latitudes than the lower deciduous forests favoured by greys which are also more tolerant of smaller forest fragments. More specifically, reds were found to require a mature canopy and a large number of trees of cone-bearing age. Such optimum conditions may not be met in managed forests where the age of trees and harvesting methods employed result in a relative scarcity of mature stands. Where there is sufficient food, red squirrels may also be found in predominantly deciduous woodland though such instances are in the extreme minority.
It is well documented that squirrel poxvirus (SQPV), a pustular dermatitis, is a major threat to red squirrel populations. Though the origin of the disease is unknown (indeed, it may have been present in the population prior to the introduction of grey squirrels), it is widely accepted that grey squirrels are the main vector for its transmission. While SQPV is not carried by all grey squirrels and is only pathogenic to a small minority, it has a very high mortality in reds. SQPV is particularly virulent, resulting in the death of the majority of red squirrel hosts within two weeks. This results in a swift community shift where the disease is introduced, with greys rapidly replacing reds. SQPV presents in a similar way to mixomatosis in rabbits: lethargy, poor coordination and facial lesions all manifest within two weeks of infection. It is possible to treat SQPV if caught at early enough, though if a squirrel is identified as having SQPV at any stage, it must be immediately removed from the population.
Control of grey squirrel populations is problematic at best. They are such an established species within the British countryside that many regard them as perhaps more integral and identifiable than the native red. Such widespread acceptance both highlights the speed with which the grey squirrel has spread across the UK and is indicative of the probable response to extreme and widespread actions such as culls. The best and most obvious course of action would be to arrest the spread of grey squirrels into areas inhabited by red squirrels. Supplementary feeding of red squirrels to the exclusion of greys could possibly bolster the red population and provide stability.
The long-term control and exclusion of grey squirrels may not be entirely feasible; the adaptability and fecundity of the species means that any form of control is likely to be costly and the benefits debatable. Despite this, the preservation of mainland red squirrel populations depends on minimising the impact of greys on prime red squirrel habitat. While control measures should be implemented, of greater importance is the management of forest habitat to favour red squirrels and the identification and utilisation of a vaccine against SQPV.
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Little studied, this small deer inhabits dense upland forests of Bawean Island, Indonesia, an area of 200km2. This represents the most restricted range of any deer species. Morphologically similar to the India’s closely related hog deer, they are a little-seen species due to their largely nocturnal habits. The total wild population is thought to be around 250 individuals. Predators including wild pigs, macaques and pythons may account for some individuals but their impact is likely to be minimal. Feral dogs pose a far greater threat and, along with habitat loss and a decline in habitat quality, are the main causes of continued decline.
Also called the ‘Pygmy raccoon’, P. pygmaeus is much smaller and occurs over a far smaller range than its better-known cousin, the common raccoon (Procyon lotor). Their insular dwarfism is due to their isolation and evolution on Cozumel Island, Mexico. P. pygmaeus is thought to exhibit more specific ecological requirements than P. lotor and island-raccoon subspecies. They prefer mangrove and wetland habitats where they forage for crabs and shellfish. Such specificity in an island species inevitably limits the extent of occurrence (478km2) and population size. Indeed, there are fewer than 250 mature individuals remaining. Anthropogenic factors and the impact of hurricanes – which can account for 60% of juveniles – pose the greatest threats.
A subspecies of Hector’s dolphin, Maui’s dolphin (originally called the North Island Hector’s dolphin) is found along the West coast of North Island, New Zealand. They are largely threatened by gillnet and trawl fisheries where it they are caught as bycatch, pollution, boat strikes and inbreeding. Maui’s conform to the common dolphin stereotypes of sociability and playfulness, grouping in pods over five strong. They have a slow reproductive cycle with females calving every 2-4 years and then only producing a single offspring. Approximately 111 individuals remain. Only 28 of these are likely to be mature females.
S. cebifrons is a gregarious pig which is endemic to the Visayan island chain – more specifically the islands of Panay, Negros and possibly Masbate – in the Philippines. The species are easily distinguished by the white band running laterally across the top of the nose which is present in both sexes. Little is known of their ecology though it is likely that in ideal circumstances it is an overall generalist. The remaining populations are fragmented, having been extirpated in 95% of the historical range by slash-and-burn agriculture, logging, hunting and hybridisation with feral animals. The species are nationally protected though enforcement is poor. The number of surviving individuals is unknown.
With a declining population numbering fewer than 250 mature individuals fragmented into sub-populations of fewer than 50 individuals in total, the Malabar Large-Spotted Civet is one of the planet’s most endangered mammals. Found in the Western Ghats, India, its favoured habitats of lowland swamps and forests have been completely removed. This forces the species to utilise previously undesirable degraded or secondary habitat and thickets in cashew plantations. Conflict with humans is a severe threat as the species will opportunistically raid for poultry. It does not currently exist within any protected areas.
Sheath-tailed bats are so-called due to the projection of the short tail through the tail membrane which effectively forms a sheath. The species is found on the islands of Silhouette, Mahe and Praslin in the Seychelles. There appears to have been several precipitous population declines; in the late 1800′s – 1900′s during the clearing of lowland forests and again since the 1970′s when the species was apparently common. It is now thought that there are fewer than 100 mature individuals remaining. Habitat loss for invertebrate prey, loss of roost sites and predation by introduced species are evident threats.
This sub-species exhibits a limited distribution in northwest Africa, specifically Algeria, Niger, Benin and Burkina Faso. Though very little is known about the species, it probably mirrors the ecology and life histories of other A. jubatus subspecies. There exists no sub-population of more than 50 mature individuals; the total number of mature individuals is thought to be fewer than 250 animals.
The Giant Sable is endemic to Angola where it inhabits the area between the Kwango and Luando rivers. This secretive species cuts a striking figure due to their large curved horns which are present in both sexes (though male horns are longer and more curved). They exhibit a preference for forest and associated riparian habitats where they a specific and preferential browsers. The population has declined and fragmented largely due to long-term military conflict and hunting; only 200-400 individuals remain. It is possible that a viable population (>50 individuals) exists within Luando Strict Reserve. Hybridisation with Roan antelope (H. equinus) is a current threat.
This species was thought to be extinct until an extant population was discovered. No specimens have been recorded since 1937 when the species was restricted to Zapata Swamp, Cuba. Introduced rats and mongooses and habitat destruction may have resulted in the extinction of the species some time ago. However, reports of tracks and droppings suggest that a small population may persist.
The brush-tailed bettong (or, to give it its Australian moniker, Woylie) belongs to the marsupial family Macropodidae which also includes kangaroos, wallabies and the like. Though it was once more widespread and could be found in a variety of habitats, it is now restricted to dry forest understory around Alice Springs, Western Australia. Despite conservation efforts, the species has continued to decline with some small populations disappearing altogether. There are translocated populations in Western Australia, New South Wales and South Australian islands which exhibit varying degrees of success.
The Yellow-tailed Woolly Monkey can be found in montane and cloud forest habitats of San Martin and Amazons in the Peruvian Andes. Originally described from a skin in the early 1800′s, it was re-discovered in 1974 (and anyone wishing to delve into this species’ history should note that it was reassigned from the genus Lagothrix to Oreonax in the early 2000′s). Since this time, the species has suffered a significant population decline as its previously inaccessible habitat was opened up by colonisation projects, road building, logging and other such projects. Habitat loss is a continued threat as is subsistence hunting by natives. Current population numbers are unknown.
This extremely rare and elusive species is endemic to the 284km2 Japanese island of Iriomote, 200km off the coast of Taiwan. Despite the largely mountainous evergreen nature of the island, the cat apparently favours lowland wetland, streams and small hills. Loss of this lowland habitat over the course of the last decade may have resulted in population decline. There are fewer than 100 individuals remaining though the population is contiguous.
B. pygmaeus is thought to have diverged from the mainland brown-throated sloth (B. variegatus) lineage when the island of Escudo de Veraguas split from the Panamanian mainland c. 8900 years ago. The species seems to exist on nutritionally poor red mangrove leaves. Its island home is less than 5km2; what little habitat it supports is declining is quality. There is no information available on its population status.
The Riverine rabbit, probably the most endangered lagomorph in the world, is endemic to the Karoo region of South Africa. Its population has been severely fragmented due to anthropogenic impacts on the landscape. These factors have also served to isolate the remaining sub-populations, limiting or omitting effective gene flow. Though the rate of habitat loss has been arrested, hunting and accidental snaring does occur and the remaining population may become extinct within 50 years without intervention. There are fewer than 250 breeding pairs remaining.
criteria when assessing species abundance. The primary criteria include population size, geographic range and the projected population size over a given period. In order to full quantify their assessment, the organisation also takes other factors such as habitat quality, exploitation, pollution, competitive species, hybridisation and introduced species into account. This approach is designed to incorporate as many parameters and influencing factors as possible so that accurate assessments can be made. It is so highly regarded that several countries including Canada, Mexico and Australia use IUCN criteria as a basis for their national strategies when assigning conservation priorities to rare or endangered species.
status according to three parameters: population size (somewhere large and everywhere small), geographic range (wide and narrow) and habitat specificity (broad and restricted). There are of course limitations inherent in this system, not least the suggestion that applying these criteria is a subjective and context-dependent endeavour. but it appears to be broadly effective nonetheless. It is worth noting that several studies, each surveying disparate taxa, have been unable to classify any organisms in the category of narrow distribution, broad habitat specificity and small population size.
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It’s like the Sarlaac, only in the sea. With a fish head. And no tentacles. Alright, it’s nothing like the Sarlaac really. It is however an excellent image. © Douglas David Seifert
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It is also a commentary on the exploitation of the natural world; more specifically whales as commodities in the nineteenth century when commercial whaling in America was a massive business. Oil and bones were extremely valuable for the range of products the could provide. The sperm whale was considered to be particularly valuable due to the unique oil – spermaceti [1] – found in its massive head.
countries turning to the more populous minkes [2]. In 1982, the IWC introduced a moratorium on commercial whaling which was to come into force in 1986 [3] after which time international trade in great whale products was also banned as all great whale species were by that time listed under Appendix I of the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES) [4, 5]. However, leeway was given to certain indigenous groups who rely on a small annual catch to sustain their communities and other loopholes allowed Norway, Japan and Iceland to continue whaling activities, either by objection to the moratorium or under the guise of ‘scientific whaling’ [3, 6, 7].
While divisive, the proposal is nevertheless pragmatic. The likelihood of countries splintering from the IWC and resuming commercial whaling irrespective of a moratorium is a very real possibility and adherence to an agreed catch limit for a ten-year period would both allow continued recovery of stocks and the development of a long-term process thereafter.
this [13, 14]. One of the most critical points is whether the IWC allow commercial whaling in the Southern Ocean Whale Sanctuary, a vital feeding ground for many species. Japan currently hunts in the Sanctuary under the auspices of scientific whaling [7] but conservationists argue that this and other whaling activities should be outlawed in such a critical area [15]. Indeed, the Australian government had suggested that it may take legal action to stop Japan’s activities in the Southern Ocean, though it has been suggested that this is a purely political move to curry good favour with voters [16].
