I have an article published at the online magazine ‘Experimentation’. It’s entitled ‘Discussing Biodiversity’ and in it I attempt to cover the quantification of and current concerns relating to biodiversity in around 1,000 words. Click here to go to that article.

If you’re interested in science and the occasional nerdy offering, my Twitter feed continues to be active: Click here for twitterings.

My previous post discussed my reasons for putting the blog on hiatus. Since then I’ve toyed with retiring it entirely. That was until Snailquake posted the following (edited) comment a few months ago which was extremely kind, gratifying and encouraging:

…I just want to say that I really love the format your blog has taken so far. It’s the zoological factoids that I enjoy. Regardless of whether a species is endangered or not, you introduce the reader to interesting facets of behaviour, evolution, or ecology. You write in a way that’s accessible to the layperson, whilst maintaining a scientific edge and providing really helpful links.

By the way, I’ve just completed a pre-university Access course, and will be starting a Zoology degree in September. One of my assignments was to write an essay and literature review on biodiversity. Thanks to your blog, I got a real toehold on the subject. I was able to include details about umbrella species versus keystone species, and find further literature to improve my work. I got full marks! I won a prize for doing so well on the course. Because of YOUR BLOG.

I do hope you’ll consider continuing in the same vein of writing about random aspects of nature that interest or inspire you – things which may be common knowledge in the field, but which are news to the rest of us. And, if you must have a particular readership in mind, how about making it Zoology undergrads?

Thus I find myself somewhat stuck when it comes to choosing blog topics. The endangered species posts are popular enough that they – species rather than lists – will undoubtedly be a recurring theme. Aside from that, I am unsure how to progress. Regardless, I’m not closing the blog; simply taking a break to conduct my research and decide exactly what it is I want to write about.

Morphologically, gibbons are very different to their ‘great ape’ counterparts. Not only do they share several primitive characteristics with old-world monkeys but they exhibit exaggerated limb proportions and extreme basal separation of the first digit of both hands and feet. Like most primates, gibbons are predominantly arboreal. Unlike other arboreal primates which are largely obligate quadrupeds, gibbons have evolved to travel and forage using three main modes of horizontal locomotion: leaping, bipedalism and, largely and primarily, brachiation.

Brachiating is, put simply, a method of locomotion whereby the animal is suspended and travels hand-over-hand, much like a child on the monkey bars in a playground. Gibbons are the only ape – and one of only two primate taxa – which utilise brachiation as the primary mode of locomotion. The other primates said to brachiate are the spider monkeys (Ateles spp.) though their reliance on their prehensile tails disqualifies them as true brachiators. Using this method, gibbons are able to move through the canopy at great speed, often using their momentum to cross large gaps between trees. They have even been reported to snatch birds from the air. Brachiating also allows the species access to relatively inaccessible food as they are able to pull thinner fruit-laden branches, which would otherwise be inaccessible, down and towards themselves.

To facilitate such a lifestyle, gibbons have evolved several adaptations, primarily in the forelimbs. Their arms are greatly elongated and their hands permanently hooked, allowing the animal to swing like a pendulum, greatly increasing the efficiency of the movement. Uniquely, gibbons also have a ball-and-socket-type joint in the wrist, granting increased agility and allowing sudden changes of direction, even while moving at high speed.

Though gibbons are famed for brachiating, there were few studies conducted which examined their musculoskeletal structure and sought to link that data to the mechanical action of brachiation. Michilsens et al. (2009) compared gibbons to ‘occasional brachiators’ such as chimps and bonobos, the semi-brachiating spider monkeys and non-brachiating species. They found that while the organisational structure of gibbon musculature is broadly similar to that of other primates, there are differences in shoulder flexors, extensors and rotator muscles which result in an increased capacity for power generation. Further, gibbon wrist and elbow flexors are capable of generating a high degree of force and the species exhibit exaggerated muscular proportionality with the greatest density around the shoulders. This adds to the pendulum effect and can be used by a flexing of the arm to change various facets of the swing. Tellingly, muscle dimensions in different gibbons species are directly comparable when body mass is normalised, meaning that the largest gibbon (the siamang) exhibits the same relative muscular dimensions as the smallest (Nomascus sp.).

References

Alfred 1992; Islam & Feeroz 1992; Sati & Alfred 2002 – Primate Info Net – Hoolock

Biegert, J. (1973). Dermatoglyphics in gibbons and siamangs. In: Rumbaugh, D.M. (Ed.), Gibbon and siamang, vol. 2, pp. 163-184. Karger, Basel and New York.

Fleagle, J.G. (1999). Primate adaptation and evolution (2^nd ed.). Academic Press, San Diego & London.

Geissmann, T. (1995). Gibbon systematics and species identification. International Zoo News. 42: 467-501.

Hollihn, U. (1984). Bimanual suspensory behavior: morphology, selective advantages and phylogeny. In The Lesser Apes: Evolutionary and Behavioral Biology (Preuschoft, D.H., Chivers, D.J., Brockelman, W.Y., Creel, N. eds.). Edinburgh, University Press. pp. 85–95.

Michilsens, F., Vereecke, E.E., D’Aout, K., Aerts, P. (2009). Functional anatomy of the gibbon forelimb: adaptations to a brachiating lifestyle. Journal of Anatomy. 215:335–354

Nowak RM. 1999. Walker’s mammals of the world. Volume I. Baltimore (MD): Johns Hopkins Univ Pr. 836 p.

Sati JP, Alfred JRB. 2002. Locomotion and posture in hoolock gibbon. Annal Forest 10(2):298-306.

This post is an edited version of a 10-minute presentation script written three months ago.

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.

References

Andren, H. & Delin, A. (1994) Habitat Selection in the Eurasian Red Squirrel, Sciurus vulgaris, in Relation to Forest Fragmentation. Oikos, Vol. 70, No. 1. pp. 43-48.

Dutton, C. (2004) The Red Squirrel: Redressing the Wrong. The European Squirrel Initiative

Forestry Commission (Report, 2002)  Towards a Forestry Commission England Grey Squirrel Policy Forestry.  Commission Publications, UK. [available online]

Gurnell, J. (1994) The red squirrel. The Mammal Society Publications, UK.

Harris, S., Morris, P., Wray, S. & Yalden, D. (n/k) A review of British mammals: population estimates and conservation status of British mammals other than cetaceans. Joint Nature Conservation Committee. [available online]

Paling, N. (2007) The Grey Squirrel in Britain:A major threat to our native biodiversity. Conservation Issues, UK

Red Alert North England (N/K) Squirrel poxvirus & treatment: Red squirrel post-mortems. Red Alert charity publication. [available online]

Teangana, D.O., Russ, J.M., Mathers, R.G. & Montgomery, W.I. (2000) Habitat associations of the red squirrel Sciurus vulgaris and grey squirrel S. carolinensis in Northern Ireland. Biology and Environment: Proceedings of the Royal Irish Academy, Vol. 100B, No. 1, 27–33

UK Biodiversity Action Plan (2007). Species action plan: Sciurus vulgaris [available online]

This piece is a heavily edited version of an essay from my BSc course. There’ll be some ‘new’ content appearing soon.

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Mammals (class: Mammalia) are a taxonomic group broadly defined by their milk-producing mammary glands, possession of hair and three ossicles in the middle ear. They also uniquely possess a neocortex; the area of the brain involved in higher functions. Most mammals give birth to live young though this is not true of the monotremes – platypus (Ornithorhynchidae) and echidna (Tachyglossidae) – which lay eggs. It is a relatively small taxa with only around 6,000 described species. These species range in size from Kitti’s hog-nosed bat (Craseonycteris thonglongyai) at 30-40mm and the Etruscan shrew (Suncus etruscus) which weighs only 1.8 grams, to the blue whale (Balaenoptera musculus) which with a length of 33m and a weight of 180 tons is the most massive animal known to have existed. True mammals first appeared in the Triassic when they exploited niches available to small, nocturnal predators. The group does not seem to have diversified much beyond these niches (though taxonomic orders were largely already in place) until the end of the reign of the dinosaurs c. 65 million years ago when they rapidly evolved to fill larger niches.

[1] Wund, M., Myers., P. (2005). Mammalia. Animal Diversity Web. [online]
[2] Tree of Life Web Project (1995). Mammalia. Mammals. Version 01 January 1995 (temporary). [online]
[3] Kumar, V. (2011). Mammalia. Encyclopedia of Life. [online]

Bawean deer (Axis kuhlii)
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.

[1] Semiadi, G., Pudyatmoko, S., Duckworth, J.W. & Timmins, R.J. 2008. Axis kuhlii. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4
[2] ARKive (2010). Bawean deer (Axis kuhlii). [online]
[3] Huffman, B. (2011). Axis kuhlii. Ultimateungulate.com. [online]
Image © Midori

Cozumel Raccoon (Procyon pygmaeus)
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.

[1] Cuarón, A.D., de Grammont, P.C., Vázquez-Domínguez, E., Valenzuela-Galván, D., García-Vasco, D., Reid, F. & Helgen, K. 2008. Procyon pygmaeus. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] McFadden, K.W., Sambrotto, R.N., Medellin, R.A., Gompper, M.E. (2006). Feeding habits of endangered pygmy raccoons (Procyon pygemaeus) based on stable isotope and fecal analysis. Journal of Mammalogy. 87(3):501-509 [available online]

Maui’s dolphin (Cephalorhynchus hectori maui)
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.

[1] Reeves, R.R., Dawson, S.M., Jefferson, T.A., Karczmarski, L., Laidre, K., O’Corry-Crowe, G., Rojas-Bracho, L., Secchi, E.R., Slooten, E., Smith, B.D., Wang, J.Y. & Zhou, K. 2008. Cephalorhynchus hectori ssp. maui. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4
[2] Slooten, E., Dawson, S.M. (2008). Sustainable levels of human impact for Hector’s dolphin. The Open Conservation Biology Journal. 2:37-43. [available online]
[3] New Zealand Ministry of Fisheries and Department of Conservation (2007). Hector’s dolphin threat management discussion document. [available online]
Image © Will Rayment

Visayan Warty Pig (Sus cebifrons)
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.

[1] Oliver, W. 2008. Sus cebifrons. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] Huffman, B. (2011). Sus cebifrons. Ultimateungulate.com [online]
Image © B. Gratwicke

Malabar Large-spotted Civet (Viverra civettina)
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.

[1] Jennings, A., Veron, G. & Helgen, K. 2008. Viverra civettina. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4
[2] Schreiber, A., Wirth, R., Riffel, M., van Rompaey, H. (1989). Weasels, civets, mongooses and the relatives: An action plan for the conservation of mustelids and viverrids. IUCN/SSC Mustelid and Viverrid Specialist Group. [available online]
[3] Animal Info (2005). Viverra civettina (V Megaspila c.). [online]

Seychelles sheath-tailed bat (Coleura seychellensis)
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.

[1] Gerlach, J., Mickleburgh, S., Hutson, A.M. & Bergmans, W. 2008. Coleura seychellensis. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] ARKive.org (2011). Seychelles sheath-tailed bat  (Coleura seychellensis). [online]
[3] Gerlach, J. (2007). Vocalisations of the Seychelles sheath-tailed bat Coleura seychellensis. Le Rhinolophe 18:xx-xx. [available online]

Northwest African Cheetah (Acinonyx jubatus hecki)
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.

[1] Belbachir, F. 2008. Acinonyx jubatus ssp. hecki. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
Image © Farid Belbachir

Giant Sable Antelope (Hippotragus niger variani)
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.

[1] IUCN SSC Antelope Specialist Group 2008. Hippotragus niger ssp. variani. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4
[2] Huffman, B. (2004). Hippotragus niger. Ultimateungulate.com. [online]

Dwarf Hutia (Mesocapromys nanus)
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.

[1] Soy, J. & Silva, G. 2008. Mesocapromys nanus. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
Image depicts Demarest’s hutia (Capromys pilorides)

Brush-tailed bettong (Bettongia penicillata)
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.

[1] Wayne, A., Friend, T., Burbidge, A., Morris, K. & van Weenen, J. 2008. Bettongia penicillata. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] ARKive.org (2011). Brush-tailed bettong  (Bettongia penicillata). [online]
[3] Start, A.N., Burbidge, A.A., Armstrong,  D. (1995). Woylie recovery plan Wildlife Management Program. 16. State Recovery Plan. [available online]
Image © Gary Lewis

Yellow-tailed Woolly Monkey (Oreonax flavicauda)
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.

[1] Cornejo, F., Rylands, A.B., Mittermeier, R.A. & Heymann, E. 2008. Oreonax flavicauda. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4
[2] Mittermeier, R.A., Wallis, J., Rylands, A.B. et al., eds (2009). Primates in Peril: The World’s 25 Most Endangered Primates 2008–2010. Illustrated by S.D. Nash. Arlington, VA.: IUCN/SSC Primate Specialist Group (PSG), International Primatological Society (IPS), and Conservation International (CI). pp. 1–92. [available online]
[3] Buckingham, F., Shaneee., S. (2009). Conservation priorities for the Peruvian yellow-tailed woolly monkey (Oreonax flavicauda): a GIS risk assessment and gap análysis. Primate Conservation (24). [available online]
Image © Platyrhinnus

Iriomote cat (Prionailurus iriomotensis)
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.

[1] Izawa, M. 2008. Prionailurus bengalensis ssp. iriomotensis. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] Okamura, M., Doi, T., Sakaguchi, N., Izawa, M. (2000). Annual reproductive cycle of the Iriomote cat Felis iriomotensis. Mammal study. 25:75-85. [available online]

Pygmy three-toed sloth (Bradypus pygmaeus)
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.

[1] Samudio, R. & Members of the IUCN SSC Edentate Specialist Group 2008. Bradypus pygmaeus. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] Anderson, R. P., Handley, C. O., Jr. (2001). A new species of three-toed sloth (Mammalia: Xenarthra) from Panama, with a review of the genus Bradypus. Proceedings of the Biological Society of Washington 114(1):1–33. [available online]
Image © Bryson Voirin

Riverine Rabbit (Bunolagus monticularis)
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.

[1] South African Mammal CAMP Workshop 2008. Bunolagus monticularis. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] ARKive.org (2011). Riverine rabbit  (Bunolagus monticularis). [online]
Image © van Dyke

Umbrella species: “a species whose conservation confers protection to a large number of naturally co-occurring species.” Roberge and Angelstam (2003)

In the face of increasing rates of habitat loss, fragmentation and species extinctions, the maintenance of global biodiversity has become one of our most pressing issues. In an effort to ensure the persistence of biodiversity, practitioners, biologists and managers have developed shortcuts for applied conservation efforts based on focal species. The umbrella species concept is one such shortcut.

Jaguar (Panthera onca) - An umbrella species for sympatric felids (2)

Focal species concepts are advantageous to conservation planners and practitioners as they conceptually permit the monitoring of a few select species rather than carrying out costly and time-consuming ecosystem-wide surveys. The underlying assumptions of the umbrella species concept state that meeting the requirements of the focal species is sufficient to meet the requirements of a number of co-occurring species. However, umbrella species do not fit a single biological profile and it is highly unlikely that a single species will confer benefits to all sympatric species.

Potential umbrella candidates should exhibit certain traits: species should be neither rare nor ubiquitous, should be sensitive to anthropogenic disturbance and account for a mean proportion of occurring species. Combining these attributes ensures that the focal species is common enough to confer adequate protection to sympatric species and protect similarly sensitive species from disturbance. These guidelines however are simply that. There is no strict definition, nor combination of life history traits commonly used to characterise an umbrella species.

Northern Goshawk (Accipiter gentiles). Effective umbrellas in the Italian Alps, ineffective in Japan (7)

Choosing umbrella species is often a reactive rather than proactive process as priority is often placed on endangered or threatened taxa. Large visible species such as mammals and birds are frequently the subject of investigations into the effectiveness of the umbrella species concept, possibly because such species are more commonly targeted by conservation efforts and frequently receive a disproportionate amount of funding and publicity. In such instances, the efficacy of the species to act as an umbrella is often determined post-hoc rather than basing management decisions on specific research and objectives. There is often a basic assumption inherent to this approach; that the minimum-area requirements for large species are likely to coincide and overlap with the area requirements of those species which are seemingly beneath the umbrella.

The umbrella species concept is increasingly used in synonymy with other focal species concepts. The most common perceived overlap occurs between umbrella and keystone species. Keystone species are those species whose presence is a key factor in maintaining the ecological structure of a community, often disproportionately so. Removal of a keystone species results in rapid and dramatic alterations in associated communities. Based on this definition and the given definition of the umbrella species concept it is evident that the two concepts are not as readily interchangeable as is often assumed. Protection of a keystone species does not necessarily confer protection to all other species which occur within its range. Similarly, removal of an umbrella species will not necessarily cause a dramatic change in community composition. It should be noted that a species can indeed fulfil both roles. North American grizzly bears are cited as keystone species for the roles they play in dispersing nutrients away from rivers (in faeces) and are also classed as umbrella species due to their trophic status and typical range size.

Sources and relevant literature

[1] Caro, T. M. (2003). Umbrella species: critique and lessons from East Africa. Animal Conservation. 6:171–181.

[2] Davis, M. L., Kelly, M. J. (2010). Carnivore co-existence and habitat use in the Mountain Pine Ridge Forest Reserve, Belize. Animal Conservation. [early view online] 1–10

[3] Fleishman, E., Blair, R. B., Murphy, D. D. (2001). Empirical validation of a method for umbrella species selection. Ecological Applications. 11:1489–1501

[4] Lambeck, R.J., 1997. Focal species: a multi-species umbrella for nature conservation. Conservation Biology 11, 849–856.

[5] Launer A. E., Murphy D. D.  (1994) Umbrella species and the conservation of habitat fragments: a case of a threatened butterfly and vanishing grassland ecosystem. Biological Conservation. 69:145–153.

[6] Noss, R. F. (1990).  Indicators  for  monitoring  biodiversity:  a hierarchical approach. Conservation Biology. 4:355–364.

[7] Ozaki, K., Isono, M., Kawahara, T., Iida, S., Kudo, T., Fukuyama, K. (2006). A Mechanistic Approach to Evaluation of Umbrella Species as Conservation Surrogates. Conservation Biology. 20(5):1507–1515.

[8] Primack, R. B. (1993).  Essentials of Conservation Biology.  Sinauer Associates Inc.,  Sunderland, Massachusetts.

[9] Roberge, J.M., Angelstam, P., (2004). Usefulness of the umbrella species concept as a conservation tool. Conservation Biology. 18:76–85.

 

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Fire Salamander (Salamandra salamandra) © Marc Dezemery

The term ‘aposematic colouration’ describes the often vivid markings of animals which may as a deterrent or warning signal to any potential predator. These signals are a secondary defence mechanism, advertising that the animal is toxic, noxious or otherwise able to defend itself in a manner which may result in injury to the predator. Such colours may also be the result of Batesian mimicry, whereby an otherwise harmless species closely resembles an unpalatable species with such a degree of accuracy that it too is avoided by experienced predators. Mutual mimicry between species sharing similar anti-predator colouration may occur (Mullerian mimicry). Colour, along with startling behaviours and/or sounds may form an effective predator deterrent.

The very definition of aposematic colouration demands that an animal’s colour be bold or vivid enough to be visible against an often homogenous background of neutral shades such as greens and browns – the more conspicuous an animal is, the more likely it will be seen by a predator. The most visible colours are most often those at the red end of the spectrum and indeed reds, oranges and yellows are extremely common. While some individuals will perish as a result of their enhanced visibility, the predator will learn to associate such marking with unpalatability or danger and thus ignore similar in the future. To quote Spock¹: “The needs of the many outweigh the needs of the few. Or the one.”.

Aposematism is most frequently associated with invertebrates and is indeed much more common in such taxa than in vertebrates.Ladybirds provide a classic example; their brightly coloured elytra warning of their toxicity. Many moth and butterfly caterpillars are similarly brightly coloured and may combine colouration with other defences such as eye-like markings. Warning colouration need not be immediately apparent or even visible. Some, like the caterpillar of the swallowtail butterfly, are cryptic from afar but quite alarmingly conspicuous close-up, a dual defence which proves to be quite effective. Similarly Poecilotheria regalis, a tarantula from India (above, left), is very well camouflaged from above but when disturbed it rears on its hind legs, displaying a black ventral surface surrounded by startlingly white or yellow limbs.

Of course, vertebrates may also – and do – express aposematic colouration. Poison dart frogs are often extremely colourful, vividly advertising their toxicity (though the degree of toxicity varies between species). Larger species such as skunks and porcupines are more boldly patterned, their greater size ensuring that they are readily visible. Though the colouration of these two species is somewhat similar, they both advertise very different characters. The skunk (and some mustelids, though to a much lesser degree) famously excretes a foul-smelling liquid which can be sprayed a considerable distance. The porcupine on the other hand advertises its impressive armoury of sharp spines; modified hairs coated in keratin which can inflict a painful or even fatal wound on an attacker.

The evolution of aposematic traits may appear somewhat paradoxical if taken from the commonly assumed starting point of successful crypsis (camouflage). If such vivid secondary defences evolved in an already successfully cryptic prey animal, it would seem logical to assume that the new rare and more conspicuous morphs would experience a greater degree of predation. Such frequency-dependent selection would surely result in the early removal of these individuals from the population. It would therefore seem more reasonable to explain the evolution of aposematic colouration in terms of species which are already conspicuous by virtue of their behaviour. In such instances the gradual evolution of brighter colouration imposes fewer costs in comparison to those imposed on already cryptic species. Enhanced colouration may also confer an array of benefits, from deterring predators to increased mating success. Evolution in this regard may thus be focussed by any one, or a combination of, sexual selection, facultative aposematism or the enhancement of pre-existing traits.

[1] Alright, Spock and Kirk. Start Trek II: The Wrath of Khan.

Ridgway's Hawk (Buteo ridgwayi)

In my previous blog post, I noted that Ridgway’s hawk (Buteo ridgwayi) has been lumbered with an incorrect common moniker (taxonomically speaking). As a member of the genus Buteo, it is in fact a buzzard and not a true hawk, all of which are species of the genus Accipiter. Both genus are indeed members of the same family, Accipitridae. Commenting on this post,  Snailquake queried the difference.

It is true that there are a great many similarities between hawks and buzzards.  Further, definitions for each group often differ between countries. For example, vultures (most commonly Turkey Vultures, Cathartes aura) in the US are commonly saddled with the name ‘buzzard’ while true buzzards are often referred to as hawks.  In this context, buzzard is a word which carries negative connotations, as exemplified by the use of the word ‘buzzard’ to define one who scrounges (scavenges). Nevertheless, there are some features which may be used to distinguish between the two genus*:

• Buzzards generally have longer wings which exhibit long, splayed primary feathers, in contrast to the short, rounded wings of hawks.
• Hawks exhibit a longer, narrower, more manoeuvrable tail, giving then greater aerial agility. Buzzard tails are generally broad and rounded.
• Buzzards are generally slower fliers, poorly adapted to pursuing swift prey. This contrasts with hawks who rely on great bursts of speed to ambush prey items.
• Hawks often inhabit and hunt in more densely wooded areas whereas buzzards often require more open habitat.
• Hawks tend to have longer legs.
• Hawks exhibit a procoracoid foramen; an opening in front of the coracoid bones which is reduced or absent in other species (Olson, 2006).

Goshawk (Accipiter gentilis)

Ridgway’s Hawk is, of course, not the only species to be saddled with a taxonomically incorrect common name. There are many examples of harriers and buzzards being labelled hawks, including Red-tailed Hawks (Buteo jamaicensis) and Marsh Hawks (Hen Harriers, Circus cyaneus). Even the Peregrine Falcon (Falco peregrinus; belonging to the family Falconidae) has been called the ‘Duck Hawk’. Thus it is evident that there is great variation in common accipitrid nomenclature which is largely dependant on location. Here in the U.K. we have only two true hawk species – the Sparrowhawk (Accipiter nisus) and the Goshawk (Accipiter gentilis) – amongst our birds of prey which also include the Common Buzzard (Buteo buteo). It is likely that the British once called all raptors ‘hawks’ (the American propensity for such may be a cultural carry-over) but that has since been superceded by recognition of the true phylogeny.

*Note that these are not hard-and-fast rules.

References

Olson, S.L. (2006): Reflections on the systematics of Accipiter and the genus for Falco superciliosus Linnaeus. Bull. B.O.C. 126: 69-70. [PDF link]

Birds first appeared during the Late Jurassic, arising from amongst the therapod dinosaurs; the infamous Archaeopteryx has been dated to c 150-145 mya. Modern birds are, by and large, much more accomplished fliers than the early avians and have evolved to fit all manner of ecological niches. There are around 9,000 known species. Representatives can be found all around the world, enriching our lives as they go about the messy business of living. Birds are generally defined by several characteristics: a toothless beak; feathers (that many dinosaurs are known to also have feathers has raised etymological issues); high metabolism; hard-shelled eggs; lightweight, robust skeleton. As birds are so varied in distribution and form, they are threatened by a great many natural and anthropogenic factors. This might seem to be counterintuitive; surely an organism capable of flight can escape such pressures. For some species, this is possible. Others are less capable of responding to limiting factors and thus exhibit similar responses to threats as do other taxa.

[1] Waggoner, B., JRH (1996). Introduction to the Aves. University of California at Berkeley. [online]
[2] Tudge, C. (2009). The Secret Life of Birds. Penguin. [available to buy]

Campbell Islands Teal (Anas nesiotis)

A. nesiotis is a nocturnal local endemic of Dent Island, New Zealand. The species was first described in 1886 but was not collected from Dent Island until 1975. In 1990, the breeding population was estimated at 60-100 birds, which declined further to 25 pairs in 1998. The species has been successfully introduced to Codfish and Campbell Islands. The total population is now estimated to be around 200 birds, though this includes captive specimens. Alien species, severe weather and avian diseases are primary threats.

[1] Birdlife International (2010). Anas nesiotis. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] Birdlife International (2010). Anas nesiotis. [online]

Black-breasted Puffleg (Eriocnemis nigrivestis)

The attractively named black-breasted puffleg is a hummingbird endemic to Ecuador where it inhabits the north-western slopes of the Volcan Pichincha and the Cordillera de Toisan. The Pinchincha population numbers approximately 160 individuals and is restricted to an area of around 34km². The total wild population has been estimated at between 250 and 999 individuals. Deforestation and habitat destruction is the greatest cause of past decline and the greatest ongoing threat to the species.

[1] Birdlife International (2010). Eriocnemis nigrivestis. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] Birdlife International (2010). Eriocnemis nigrivestis.  [online]
Image © Benjamin Schwartz

Enigmatic Owlet-nightjar (Aegotheles savesi)

Sighted only once since 1960, A. savesi is endemic to New Caledonia where it likely exists as a tiny and spatially restricted population. Little is known of the species, even amongst local people. It is thought that it exploits a more terrestrial lifestyle than that of other Aegotheles species. Based on a similar species – A. cristatus – it is thought that introduced predators and habitat loss are primary threats.

[1] Birdlife International (2010). Aegotheles savesi. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] Birdlife International (2010). Aegotheles savesi. [online]

Bengal Florican (Houbaropsis bengalensis)

The Bengal florican is a bustard – the Family Otididae which includes the heaviest flying bird, the great bustard (Otis tarda) – which occurs in two populations; one in India, through Nepal, the other in southeast Asia. These populations fragmented into small sub-populations. The total global population is thought to be between 250 and 999 individuals. There have been no recent surveys of the Indian population. The primary threat is loss of key grassland habitat.

[1] Birdlife International (2010). Houbaropsis bengalensis. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] Birdlife International (2010). Houbaropsis bengalensis. [online]

Blue-throated Macaw (Ara glaucogularis)

A much loved staple of the pet trade, the blue-throated macaw saw its population decimated in three generations. The remaining wild population – estimated at around 250-300 individuals – is found in Llanos de Mojos, Bolivia. Drastic reduction of the trade in wild-caught birds has halted the decline and there are signs of recovery. Other threats are hunting for feathers and meat, inter-specific competition and inbreeding of fragmented sub-populations.

[1] Birdlife International (2010). Ara glaucogularis. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] Birdlife International (2010). Ara glaucogularis. [online]
Image © Jeff Kubina

Masafuera Rayadito (Aphrastura masafuerae)

The Masafuera Rayadito is a member of the ovenbird family (Furnariidae), a family famous for the horneros (Furnarius spp.) which build oven-like clay nests. The Rayadito is more demure, nesting in natural cavities. It is found only on the island of Alejandro Selkirk in the Juan Fernandez Islands, Chile. Recent surveys put the population at c. 248 birds though based on availability of suitable habitat, the total population may number as many as 1,000. Primary threats are habitat loss, climate change and an increase in red-backed hawks (Buteo polysoma exsul).

[1] Birdlife International (2010). Aphrastura masafuerae. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] Birdlife International (2010). Aphrastura masafuerae [online]

São Tomé/Dwarf Olive Ibis (Bostrychia bocagei)

First sighted in 1990, this species was long considered a subspecies of the larger olive ibis (Bostrychia olivacea). It is endemic to São Tomé, São Tomé e Príncipe where it inhabits catchments in the south-west and centre of the island. Threatened by habitat loss and intense hunting pressure, the population has dwindled to fewer than 50 birds.

[1] Birdlife International (2010). Bostrychia bocagei. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] Birdlife International (2010). Bostrychia bocagei [online]
Image © Christian Hinzen

Réunion Cuckoo-shrike (Coracina newtoni)

Neither a cuckoo nor a shrike, C. newtoni can be found in two small patches of forest to the north of the island of Reunion in the Indian Ocean. One of these sub-populations now consists of fewer than 25 individuals. From 2003 to 2007, numbers of unpaired males increased by over 10% every year, indicative of a heavy male skew in the population. Predation by rats, disturbance, invasive plants and inter-specific competition continue to contribute to the decline of the species. Fewer than 25 breeding pairs remained as of 2007.

[1] Birdlife International (2010). Coracina newtoni. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] Birdlife International (2010). Coracina newtoni. [online]
Image © Jean-Michel Probst

Kaempfer’s Woodpecker (Celeus obrieni)

Since collection of the type specimen in 1926, this Brazilian woodpecker was thought extinct for several decades. However, a male was caught in a mist net in 2006; several specimens have been recorded since. It is known from several states where it is thought to be associated with bamboo and babassu palm forest. The current population is cautiously estimated at 50-250 individuals. Due to the number of captures and the likely size of its range, however, it is likely that the population is large and the species may soon be downlisted.

[1] Birdlife International (2010). Celeus obrieni. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] Birdlife International (2010). Celeus obrieni.  [online]
Image © Ciro Albano

Ridgway’s Hawk (Buteo ridgwayi)

Thos familiar with bird taxonomy will notice that the common name of this species is a misnomer. Rather than being a true hawk (Accipiter spp.), Ridgeway’s is in fact a buzzard (Buteo spp.). Once recorded from Haiti and many associated islands, the species is now likely restricted to Los Haitises National Park in the Dominican Republic. The species is undergoing an annual decline of c. 5-10% of breeding pairs at one site which also experiences 10-15% annual forest loss. There were estimated to be between 80 and 120 breeding pairs as of 2006. A translocation effort by the Peregrine Fund is ongoing.

[1] Birdlife International (2010). Buteo ridgwayi. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] Birdlife International (2010). Buteo ridgwayi. [online]

Black Stilt/Kakī (Himantopus novaezelandiae)

This species has been subjecty to intensive management efforts since 1981 when the population was just 23 individuals. Despite contstant effort, the species remains one of the rarest shorebirds in the world. The wild population has almost certainly been saved from extinction by the annual release of large numbers of captive-bred birds. Once widespread across North and South islands of New Zealand, breeding is now restricted to the Waitaki Valley on South Island. The total population stood at 78 birds as of 2007-08, 20 of which were breeding pairs. Predators, nest-site disturbance and stochastic weather events are the primary threats.

[1] BirdLife International (2009). Himantopus novaezelandiae. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] BirdLife International (2009). Himantopus novaezelandiae.  [online]
Image © Yang Zhang

White-chested White-eye (Zosterops albogularis)

Looking much like a colourful warbler, Z. albogularis inhabits Norfolk Island where the remnant population is confined to Norfolk Island National Park. Despite occasional reported sightings, official surveys have been unable to find a single individual. If the species persists, it does so in low numbers. It is threatened by rat predation and the destruction and alteration of suitable habitat.

[1] Birdlife International (2010). Zosterops albogularis. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] Birdlife International (2010). Zosterops albogularis. [online]

Beck’s Petrel (Pseudobulweria becki)

Recently rediscovered (2007-08), Beck’s petrel is generally found along the island chain which includes Papua New Guinea and the Solomon Islands. The extent of its breeding range or area of occupancy whilst at sea are unknown. The global population is thought to be larger than originally estimated due to the sighting of around 160 birds between New Britain and New Ireland in 2008. The species may be threatened at its breeding grounds by invasive predators.

[1] Birdlife International (2010). Pseudobulweria becki. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] Birdlife International (2010). Pseudobulweria becki. [online]
Image © Hadoram Shirihai

Raso Lark (Alauda razae)

As its common name attests, A. razae is found only on the islet of Raso (7km²) in the Cape Verde Islands. The species’ population appears to fluctuate in response to climactic conditions with recorded numbers veering from a low of 20-50 pairs to around 250 individuals. The species is especially vulnerable during periods of low abundance as the sex ratio becomes skewed 3:1 towards males. Primary threats are grought and nest predation.

[1] Birdlife International (2010). Alauda razae. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
[2] Birdlife International (2010). Alauda razae. [online]

Image via Wikipedia

News emerged this week that trial culls of magpies and crows are to go ahead at several sites in an effort to arrest the decline in UK songbirds [1]. Whether this action is justified or not is being hotly disputed, with the RSPB in the ‘anti-cull’ corner and Songbird Survival proclaiming its support. While this announcement largely appeared as if out of the blue, this particular issue has raised its head repeatedly over the years [2, 3, 4, 5, 6]

Do most UK corvids (birds of the crow family, Corvidae) take the eggs and/or nestlings of other birds? Undoubtedly. They are extremely adaptable and intelligent opportunistic omnivores. Are songbirds in decline? Generally speaking, yes.  And they have been in decline for the past 25 years or so.Data published a in January by DEFRA described the following [breeding] bird population fluctuations (note woodland and farmland bird population trends) [7]:

• Farmland birds: Down 8% between 2003 and 2008.
• Woodland birds: Little change between 2003 and 2008.
• Water and wetland birds: Down 5% between 2003 and 2008.
• Seabirds: Up 10% between 1999 and 2009.
• Wintering waterbirds: 9% between 2002-03 and 2007-8.

Source: RSPB, BTO, Defra Note: figures in brackets show the number of species

But are corvids responsible for these declines? No. At least, not solely. As common predators, they unquestionably impact the populations of prey species. And in certain situations, it may be necessary to control their numbers. However, if the current trial is to be the precursor to a general cull, I’d be intrigued to know whether the science supports such action (and indeed, I’ll be doing some research on this topic). A recent study by the BTO found that there is no evidence to support the hypothesis that common avian predator (and corvids surely count as such) abundance is correlated with large declines in songbird populations [8].

“Although it is widely accepted that, in some situations, predators of nests, chicks and full grown birds do affect the abundance of avian prey species, until now the evidence that such effects are widespread amongst songbirds has been weak, having been based on a relatively small number of studies.”[8]

It seems that we must find a non-anthropogenic cause for the decline in songbird numbers, so we point our fingers at cats, raptors, corvids, squirrels; anything and everything but ourselves. As is so often the case, the decline in songbird numbers is likely to be largely attributable to human activities and then largely changes in land management. I’ll be interested to read the results of these trials though at the moment it appears to be little more than a case of throwing the sheep to the wolves, as it were.

[1] The Telegraph – Magpies and crows to be culled to protect songbirds
[2] Mail Online – The magpie menace slaughtering our songbirds
[3] The Telegraph – Magpies not to blame for songbird decline
[4] The Guardian – Magpie threat to songbirds
[5] Times Online – Charities in dispute over culling magpies
[6] Times Online – Songbirds and culling magpies
[7] DEFRA – Population of wild birds: 1970 – 2009
[8] BTO – Are predators to blame for songbird declines?

 

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