Hi everybody! Just wanted to let you all know that this is my last post for the university term :( but thanks for reading! I would very much like to continue with the blog in future, although I have far too much work for the foreseeable future (as I'm sure many of you can sympathise with!).
The Minute Leaf Chameleon, one of the smallest lizards ever found! Photo: Arkive.
During the past couple of months we have looked at some of the current impacts on biodiversity, recent related news stories and some amazing species in imminent danger of extinction. Some of my favourite parts have been writing about the stories and scientific research on Lonesome George (the deceased remnant of the Pinta Island tortoise) and the proposed British badger cull. We have also looked at topics such as the uses of biodiversity, the effect of global warming on biodiversity, the use of planetary boundaries, eutrophication and the monetary cost of conservation. I sincerely hope I have managed to impress on you the huge diversity of life on Earth, how wonderful it can be, and how much it is threatened by negligent human activity. I also hope I have inspired some of you to seek out more information on biodiversity and conservation (like I have been prompted to while writing these posts!).
Hi everybody; just wanted to say a big thank you to everyone who read and commented on my blog in the past few months! For those of you with a continuing, or newly established, interest in biodiversity I thought I would link some other related blogs I have been looking at. ---------------------------------------------------------------------------------------- EDGE (Edge of Existence) Blog: various bloggers write on recent updates in the field of biodiversity, and recount the actions of conservationists at EDGE (by ZSL). The Artful Amoeba: now located at Scientific American, Jennifer Frazer writes this blog on the 'weird wonderfulness of life on earth'. This is full of intriguing posts, written in an accessible tone. All About Wildlife: an educational blog for wildlife lovers that has recently posted their list of top 10 endangered species for 2013.
The Northern Sportive Lemur featured in All About Wildlife's top 10 endangered species for 2013. Photo: Coke Smith, obtained from blog.
Lost Worlds: a blog series by Dave Hone at The Guardian. As a palaeontologist, most posts are on palaeontology and evolutionary biology (which are my main interests!), but also discusses other topics such as science in the media. Very informative, accessible and interesting to gain a professional point of view.
Body Horrors: sporadic, and not that relevant to my theme of biodiversity. However I really enjoy keeping up to date with this blog by Rebecca Kreston. Posts are on the interaction of infectious diseases, the human body and sociology, and are written in a funny, entertaining and intelligent style. Really worth a look!
Following our quick look at the more generalised for and againsts (that I can see) of the proposed badger cull, I thought I would go through the findings and contradictions in some of the scientific studies that are used to inform on this current debate. As I stated, each 'set' of papers appear to directly contest each other, highly complicating matters!
Badgers are at risk of being widely hunted in Britain based on some papers which conclude a cull could reduce incidences of bovine TB. Picture source.
Following the Krebs Report and Bourne Report from 1997 and 1998 respectively (the latter initiating a trial cull to determine results; in Part 2), a review was published in 2005 by Reading University.
This was to address the question 'how responsible are badgers for higher incidences of TB in cattle'? As Krebs (1997) points out, an association between TB infection in badgers and cattle is not evidence of high transmission between the two. This adds increased uncertainty over how much of a change badger culling could produce (ISG, 2007); if there is little transmission then badger culls will be ultimately pointless. This review from Reading (2005) concluded there is strong evidence that badgers provide a reservoir for TB infection, however culling strategies functioning in other countries were found unlikely to help in Britain. There appears to be little quantitative information on transmission from badgers, although Bohm, Hutchings and White (2009) found that badgers and cattle come into contact with each other much more often than previously thought; possibly indicating high badger-cattle infection rates. In 2007 the ISG published their follow up Bourne Report from that in 1998, which discussed the results of their trial badger cull. In my opinion the section on recommendations and conclusions is most interesting to the controversy. The study seems to practically damn any feasible badger cull, stating that only a sustained and coordinated proactive (i.e. before badgers/cattle are infected in an area) cull would be effective. This seems like far too great a measure (and too expensive and difficult!) against one species. The paper contains many telling statements that comment on the feasibility and likely futility of a British badger cull, for example:
"...we conclude that badger culling is unlikely to contribute positively, or cost effectively, to the control of cattle TB in Britain." (Pg 23).
"...priority should be given to [...] application of control measures to cattle, in the absence of badger culling." (Pg 23).
"It is highly unlikely that reactive culling (which is what the proposed cull would be) could contribute other than negatively to future TB control strategies." (Pg 23). They concluded that reactive culling (the most likely form) actually increased bovine TB within culled areas!
"Repeated reactive culling is likely to increase, rather than decrease, the detrimental effect associated with localised culling." (Pg 23).
"Culling badgers under license not only could fail to achieve a beneficial effect, but could increase the incidence of cattle TB and increase the geographical spread of the disease" (Pg 24).
The study also concluded that cattle-cattle transmission is additionally very important in the spread of TB within infected areas, and between new areas.
However the King Report (also 2007) assessing this scientific evidence came to an entirely different conclusion; it stated that the removal of badgers could significantly contribute to control of bovine TB where its incidence is high and persistent (i.e. reactive culling)! This lends support to another side of the debate, however I, and the ISG, are not sure how they came to this. The ISG published a swift reaction to the King Report, also in 2007, asking how they so misinterpreted the findings, given the former state "badger culling can make no meaningful contribution to cattle TB control in Britain." A study by Jenkins, Woodroffe and Donnelly (2010) further supports this conclusion that a badger cull would be ultimately futile in reducing bovine TB incidences. This found that culls initially cut TB (a fall of ~38%), however any benefits disappeared within three years of the cull being carried out. Additionally, they found culling caused perturbation; infected badgers were disturbed and moved into new areas, sometimes causing increasing transmission in nearby zones. Again there is a comparative study that contests these results; the Farmers' Union of Wales in 2010 used a computer model to show herd incidences of TB could be reduced by about 5-30% in a five year cull, and even more in the few years following. However this could be subject to slight bias, given farmers obviously have much more to gain from a badger cull than most (even if reductions in bovine TB were negligible).
In some countries badgers are trapped and then shot as a way of culling, to attempt to reduce bovine TB. Picture source.
Personally, I know I would from the start favour preservation of another species, however I don't believe that there is enough significant evidence out there to prove that a badger cull would have any real effect on bovine TB incidence in Britain. I think with this limited support the passing of any widespread cull would be basically groundless (until further studies are published), and that this is not a sufficient basis for hunting a species.
After this look at some of the main studies informing on the badger cull, hopefully you will feel better equipped to decide for yourself whether a cull would be worthwhile!
I thought we should kick of our analysis of the debate over badger culling with some general (and sometimes ethical) for and against points I have come up with, followed by the initial scientific papers that started the controversy. Many vehemently believe it is ethically wrong to destroy another species just to provide slight aid to our civilisations; fundamentally as this promotes humans as 'more important' than other groups. While I believe this is not true (clearly, given my past posts...), and greatly object to culling of other species just because they are a nuisance, I also believe the farmers that call for badger hunts have a point. We should therefore look at both sides of the argument, if only to be more informed when we come down on one or the other.
Reasons FOR a badger cull:
Protecting cattle against TB could increase agricultural productivity; providing lower food prices, and food to more people.
Protecting cattle helps protect farmers' livelihoods, as less of their produce is wasted.
Bovine TB costs society a huge amount every year; £500m in the last 10 years according to the BBC, decreasing its transmission would save a fair amount of money.
Reasons AGAINST a badger cull:
I believe, as do many, that it is unjust to massively harm the survival of another species, just to marginally help our own.
Culling methods must be assuredly humane - this seems unlikely to happen, but rather that many individuals will be trapped and left to die.
Local badger culls could further spread TB: survivors could migrate, damaging so far unaffected areas, as Sir David Attenborough notes. The Dorset Wildlife Trust also states culls cause disruption and movement between badger groups, resulting in increased numbers of infection of badgers and cattle.
To provide any sort of significant reduction in bovine TB, an equally significant number of badgers must be killed.
There will be a high monetary cost involved to hunt enough badgers in each area; either the value of a huge number of traps or guns to shoot them.
One of the first papers to lend scientific evidence to the problem of bovine TB was the Krebs report in 1997. This concluded that badgers are a significant source of TB infection in cattle (although at this point this was mostly unfounded), however at the time the effectiveness of badger culling as a control measure couldn't be quantified. Thus it recommended DEFRA (the governmental department responsible) set up an experiment on culling badgers. The following year the first Bourne report was published by the ISG. They followed the recommendations set out in Krebs (1997), announcing a randomised badger culling trial and research; the results of which would be published in 2007.
The following scientific papers and reports published on this topic contain information on the literal results and interpretations from test culls. However it appears that each paper published has an opposite discussing contradictory findings! Therefore in part 3 we will look at whether there is significant scientific support that a country-wide badger cull can help reduce bovine TB.
Today is our last Critically Endangered Species of the Week; sad, I know! All I hope is that this segment has helped highlight a few of the many endangered species in different evolutionary groups, and that some of you may think more than you did about what a large impact human society is having on other species. Thanks for reading these, and today I thought we would look at a larger, more well-known species: the Black Rhinoceros.
The Black Rhinoceros, native to Africa and critically endangered. Photo from the IUCN.
About: The Black Rhinoceros, Diceros bicornis, is one of the most well-known critically endangered species on Earth; being a somewhat 'poster-species' against poaching. They have two horns, the anterior longer than the posterior, and sometimes a third horn further back [2, 3]. Individuals may weigh 800-1,400 kg [3]. Black Rhino occur in a variety of habitats, from desert in Namibia to wetter forested areas. They are found in highest densities on savanna. The rhinos are browsers, feeding mainly on small Acacias and other woody species of plant, herbs and succulents [1, 2, 3]. Like White Rhino, Black Rhino are actually grey but have an identifiable pointed upper lip due to plucking off leaves and fruit for their browsing diet [2, 3]. Aside from females and their offspring, individual Black Rhino are solitary [2, 3]. Females reproduce every two and a half to five years, with calves becoming independent only after three years [2]. Black Rhino can reach 40-50 years of age [3].
The Black Rhinoceros, Diceros bicornis, has been hunted almost to extinction for it's horn. Photo from National Geographic.
Geographical Range in the wild: There are actually three remaining subspecies of the Black Rhino, due to their occupation of different African countries. The D. b. michaeli subspecies is found in primarily Kenya, South Africa and Tanzania [1, 3]. D. b. bicornis occur likely in only Namibia and South Africa [1, 3], and D. b. minor can be found in South Africa, Zimbabwe and southern Tanzania [1, 3]. All subspecies have much wider historical ranges, but are extinct in many of their native African countries - a fourth subspecies is also considered extinct.
Geographical range of the Black Rhinocerous. Red = extinct, Orange = extant, Purple = Reintroduced, Blue = Introduced. Map from IUCN.
I find it particularly sad that the IUCN cannot even release more detailed information than the country on the whereabouts of rhino populations for fear of poaching.
Number left in existence: Throughout much of the 20th century the Black Rhino was the most numerous of the world's Rhino species, with a population of around 850,000 [1]. The population of Black Rhino has declined by around 97.6% since 1960 [1, 3]. Numbers were at an all-time-low in 1995 with 2,410 (Emslie and Brooks, 1999), but have steadily increased to 4,880 by the end of 2010 (Emslie, 2006; AfRSG data 2008, 2011) [1, 3]. However current numbers are still 90% lower than they were three generations ago [1]. Why they are endangered:
The main, historical, threat to the Black Rhino is poaching for the international trade in rhino horn [1, 2, 3]. A recent surge in black market prices for rhino horn has lead to an increase in poaching in some ranges; this has also coincided with its new use to supposedly treat cancer (unsubstantiated).
They are hunted for traditional rhino horn use in Chinese medicine, and secondly for ornamental use; i.e. it is highly prized to form handles of ceremonial daggers used in some Middle East countries [1, 2].
Black Rhino populations have also suffered due to African civil unrest and free flow of weapons since the 1960s; this has hampered conservation efforts (Emslie and Brooks, 1999; 1, 3). Due to this, funds have also been diverted away from wildlife conservation, and further harmed the species.
Like other species, the Black Rhino is also under threat of habitat changes and alien species [3].
What can we do to help? Many measures to protect the Black Rhino are already in place (thanks to it being a large, well-known species): all international commercial trade in Black Rhinos and their products has been prohibited; many remaining individuals are present in fenced sanctuaries with more concentrated law enforcement; populations are constantly monitored and managed; and animals have been translocated to set up new populations [1, 3]. Additionally, the rhinos are now managed by a range of different stakeholders to increase their long-term security, and several regional Africa rhino conservation initiatives operate [1, 3]. Thankfully all that needs to be done to hopefully improve population numbers is continued enforcement of the above measures, and increased effort to improve biological management so we can aid rising populations more. However, the Black Rhino is very much in the minority of endangered species that are actually receiving sufficient aid, and so it needs to be remembered how much other species need similar help.
Watch this video to see Black Rhino closer up!
From the National Geographic on the move of a Black Rhino
The incidence of Tuberculosis (TB) in badgers, the spread to cattle, and the resulting proposed cull of UK badgers has seen huge news coverage and debate in the past year. This story resurfaced after further scientific investigation gave way to a proposed badger hunt, which was postponed as of October this year. The most famous opponent to this cull is Dr Brian May, who has been campaigning to stop what some see as unnecessary killing of native species; and even has his own website to this end. The problem lies in the fact that badgers can spread TB to cattle (and vice versa), as the same bacterium causes the disease in both animals; Mycobacterium bovis. Once cattle are infected with TB, they can easily infect other cattle, and so have to be immediately killed; harming agricultural production.To get up-to-date on the matter as it stands, I suggest visiting the BBC Q&A on the topic.
Badgers are still threatened by a possible go-ahead on the proposed cull to reduce incidences of bovine TB. Source.
So over the next couple of posts I thought I would look at the scientific papers that provide evidence on whether a badger cull could be effective, and therefore whether it is right that we should seriously harm another species to aid our agriculture.
This followed the study published in Current Biology by Ridgway et al., 2012, concluding that a beluga whale kept at the National Marine Mammal Foundation in San Diego had learned how to modify sounds to make them more human-like. Apparently this sounded so convincing it fooled a diver into thinking someone had yelled to get out the water; surfacing and calling "who told me to get out?". Ridgway et al., 2012, recorded and analysed these sounds, determining that they were several octaves lower than regular calls, and demonstrate "spontaneous mimicry of the human voice, presumably a result of vocal learning".
Figure 1 from Ridgway et al., 2012, demonstrating acoustic similarities between human vocalisations (A) and Noc's vocalisations (B).
The researchers have therefore interpreted Noc's unusual vocalisations as an attempt to mimic humans, due to the presence of human keepers and divers. They found that Noc's vocalisations had an amplitude rhythm similar to human speech (as in figure 1 above); vocal bursts were also similar, averaging around 3 per second. Noc has remained vocal, but stopped demonstrating speech-like behaviour after he matured. Vocalisations similar to human speech have also been recorded in white (beluga) whales in the wild, however Ridgway et al., 2012, note that Noc was not a 'good mimic' compared to well-known mimics like parrots. Although it does seem clear that a close association with humans can produce definite behaviour of vocal learning in other species.
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