Toothed conflict

1 11 2012

Left: An Anatolian shepherd (a Turkish breed improved in the USA) guiding a herd of boer goats whose flesh is much appreciated by people in Namibia and South Africa. Right: A cheetah carrying a radio-transmitter, within a project assessing range movements of this feline for the Cheetah Conservation Fund. Cheetahs refrain from moving close to the herds when the latter are looked after by the guardian dogs. Photos courtesy of Laurie Marker.

Another corker from Salva. He’s chosen a topic this week that’s near and dear to my brain – the conservation of higher-order predators. As ConBytes readers will know, we’ve talked a lot about human-predator conflict and the inevitable losers in that battle – the (non-human) predators. From dingos to sharks, predator xenophobia is just another way we weaken ecosystems and ultimately harm ourselves.

Rural areas devoted to livestock are part of the natural landscape, so it is inevitable (as well as natural) that predators, livestock and humans interact in such a mosaic of bordering habitats. However, their coexistence remains an unresolved conservation problem. 

When two species, people, political parties, enterprises… want the same thing, they either share it (if possible) or one side eliminates the competitor. The fact that proteins are part of the diet of humans and other carnivore species has resulted in a trophic drama that goes back millennia. Nowadays, predators like eagles, coyotes, lions, wolves and raccoons are credited for attacks on cattle and poultry (and people!) in all continents. This global problem is not only economic, but interlaces culture, emotion, policy and sanitation (1-4). For instance, some carnivores are reservoirs of cattle diseases and contribute to pathogen dispersal (5, 6).

Management options

Managers of natural resources have implemented three strategies to handle these sorts of issues for livestock breeders in general (7). Those strategies can be complementary or exclusive on a case-by-case basis, and are chosen following cost-benefit assessments and depending on the conservation status of the predator species involved. (i) ‘Eradication’ aims to eliminate the predator, which is regarded as noxious and worthless. (ii) ‘Regulation’ allows controlled takes under quota schemes, normally for pre-defined locations, dates and killing methods. ‘Preservation’ is applied in protected areas and/or for rare or endangered species, and often requires monitoring and measures set to prevent illegal harvest or trade. Additionally, many livestock breeders receive money to compensate losses to predators (8).

Many experts now advocate non-lethal (preventive) measures that modify the behaviour of people, livestock or predators (2, 7). The use of livestock-guarding dogs is one of those preventive measures (9). As an example, Laurie Marker (director of the Cheetah Conservation Fund) et al. (10) studied the use of 117 Anatolian shepherds adopted by Namibian rangers between 1995 and 2002 (Fig. 1). In this African country, cheetahs (Acinonyx jubatus) selectively forage on small-sized cattle and juveniles. Despite this feline being protected nationally, Namibian laws authorise rangers to shoot cheetahs in situations of risk to people and their properties, with more than 6,000 cheetahs having been killed in the 1980s alone (11). Through face-to-face interviews, Marker found that since the arrival of the Anatolian shepherds, > 70 % of the rangers perceived a pronounced reduction in cattle mortality (10). Although, the use of livestock-guarding dogs has worked out fine in many places worldwide, it is no panacea. In many other instances, the dogs dissuade some predator species and not others from harassing the livestock, or are only effective in combination with other measures (7, 9). Read the rest of this entry »





Can Australia afford the dingo fence?

18 05 2012

I wrote this last night with Euan Ritchie of Deakin University in response to some pretty shoddy journalism that misrepresented my comments (and Euan’s work). Our article appeared first in The Conversation this morning (see original article).

We feel we have to set the record straight after some of our (Bradshaw’s) comments were taken grossly out of context, or not considered at all (Ritchie’s). A bubbling kerfuffle in the media over the last week compels us to establish some facts about dingoes in Australia, and more importantly, about how we as a nation choose to manage them.

A small article in the News Ltd. Adelaide Advertiser appeared on 11 May in which one of us (Bradshaw) was quoted as advocating the removal of the dingo fence because it was not “cost effective” (sic). Despite nearly 20 minutes on the telephone explaining to the paper the complexities of feral animal management, the role of dingoes in suppressing feral predators, and the “costs” associated with biodiversity enhancement and feral control, there wasn’t a single mention of any of this background or justification.

Another News Ltd. article denouncing Ritchie’s work on the role of predators in Australian ecosystems appeared in The Weekly Times the day before, to which Ritchie responded in full.

So it’s damage control, and mainly because we want to state categorically that our opinion is ours alone, and not that of our respective universities, schools, institutes or even Biosecurity SA (which some have claimed or insinuated, falsely, that we represent). Biosecurity SA is responsible for, inter alia, the dingo fence in South Australia. Although our opinions differ on its role, we are deeply impressed, grateful and supportive of their work in defending us from biological problems. Read the rest of this entry »





Twenty landmark papers in biodiversity conservation

13 10 2011

While I can’t claim that this is the first time one of my peer-reviewed papers has been inspired by ConservationBytes.com, I can claim that this is the first time a peer-reviewed paper is derived from the blog.

After a bit of a sordid history of review (isn’t it more and more like that these days?), I have the pleasure of announcing that our paper ‘Twenty landmark papers in biodiversity conservation‘ has now been published as an open-access chapter in the new book ‘Research in Biodiversity – Models and Applications‘ (InTech).

Perhaps not the most conventional of venues (at least, not for me), but it is at the very least ‘out there’ now and freely available.

The paper itself was taken, modified, elaborated and over-hauled from text written in this very blog – the ‘Classics‘ section of ConservationBytes.com. Now, if you’re an avid follower of CB, then the chapter won’t probably represent anything terribly new; however, I encourage you to read it anyway given that it is a vetted overview of possibly some of the most important papers written in conservation biology.

If you are new to the field, an active student or merely need a ‘refresher’ regarding the big leaps forward in this discipline, then this chapter is for you.

The paper’s outline is as follows: Read the rest of this entry »





Classics: Mesopredator Release

17 03 2010

© J. Short

Although popularised by Crooks & Soulé (1999), Soulé et al. (1988) first gave us the term that described how entire ecosystems can become unbalanced by a reduction of a higher trophic-level predator exerting so-called ‘top-down’ control on the abundance of species occupying lower trophic levels.

The idea had theoretical support in ecology (Wright et al. 1994; Litvaitis & Villafuerte 1996), but it was not until Soulé and colleagues described how the decline of dominant predators combines with habitat fragmentation to release top-down pressure on smaller predators, thereby increasing predation rates on prey lower down the trophic web.

Crooks & Soulé (1999) described an example where the decline in coyotes (Canis latrans) in combination with urbanisation-driven habitat fragmentation led to an increase in cat (Felis catus) densities and the subsequent decline in scrub-breeding birds. More recent examples attest to the importance of the mesopredator release phenomenon: Myers et al. (2007) described how the decline in large coastal shark species has allowed mesopredator cownose rays (Rhinoptera bonasus) to increase, leading to a reduction in commercially important shellfish densities; and Johnson et al. (2007) showed how dingoes (Canis lupus dingo) in Australia suppress populations of exotic predators such as cats and foxes, leading to more locally abundant populations of native marsupials (see previous post).

Conservation biologists have benefited from this knowledge because we’ve realised that top-order predators affect far more than their immediate prey. These examples really hit home how a fully functional community is required for ecosystem stability, so we should strive to preserve complete complements of communities, not just our favourite species.

CJA Bradshaw

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