Conservation or management?

The international furore over cats in New Zealand took my attention from Perissodactyla for a week to also post on my other blog but I am back now. While away I have been thinking about how to start the topic of populations and how we conserve or manage them.

Getting populations to grow is a central objective of wildlife conservation – fundamental to the rescue of rare and declining species. Larger populations are less vulnerable to unexpected catastrophes, like extreme weather events, and more robust to environmental changes, especially because they retain a greater diversity of individuals – genetic and cultural variation.

Grevy’s zebra. Only around 750 remain in the wild.

Larger populations are also more likely to sustain a harvest by another component of the ecosystem’s biodiversity, like a predator or parasite, or by people for food, clothing or recreation. It is more difficult to extinguish or over-harvest a larger population and diverse populations are more adaptable to changing circumstances. Thus, conservation is successful when it makes populations larger.

Reducing or maintaining a population at a particular size is a central objective of wildlife management. Population growth may need to be controlled or reversed to prevent a species from being at densities where it impacts other values of the landscape, like other plant and wildlife diversity, or the services that the ecosystem provides, like clean water. Some populations are pest species because they impose a social or economic cost on communities – impacting the quality of peoples’ lives. A pest population’s decline is the first step towards its eradication.The Perissodactyla are interesting because species are rare or endangered but also common. They are conserved in some ecosystems, but regarded as a pest in others.

Black rhinoceros in iMfolozi Game Reserve, South Africa. Photo: Dale Airton

The Javan and Sumatran rhinoceros are amongst the most endangered large mammal species on the planet. Black rhinoceros of southern and eastern Africa are critically endangered and illegal hunting for their horns threatens their extinction.

The world’s tapir were recently common but are in rapid decline due to deforestation in equatorial Asia and South America.

Plains zebra is amongst the most common ungulates on the African continent, but Grevy’s zebra number only around 750 individuals and they are endangered. Domestic horses are one of our most common large animals and released to re-wild or become feral on the landscape are regarded as pest species by some.

Posting under the category ‘Population growth’ I will explain how populations change and how that change can be measured and calculated. The uncertainties inherent in estimates of population growth will be discussed and the reliability of estimates for horses and rhinoceros debated. I will use characters of these species lives to calculate the maximum population growth rate that it could achieve under best conditions. I will evaluate some of the extraordinary claims about how fast these populations can grow or how slowly they are growing – hoping to inform the debates around the world about the conservation and management of wild Perissodactyla.

Knowing your wild horse

A growing number of more technical tools and techniques in wild animal research make advances in our understanding of animal behaviour and ecology possible. Many of the most fundamental and important tools and techniques remain rudimentary however, like ways to identify individual animals. Nevertheless, the successful application of even rudimentary techniques has its challenges.

The accurate and repeatable identification of individuals is critical to studies of wild animal behaviour and ecology, and the demography of populations. It allows us to reliably attribute different observations at different times to the same individual. From individual observations we can build an understanding of how populations’ respond to change.

In wild animal research identification must be possible quickly from a distance. Animals might not be approachable. They may flee from the researcher or live in habitats where visibility is poor. Fortunately, it is comparatively easy to distinguish individual horses.

The coat (pelage), and mane and tail, colours of horses vary in ways that are richly described by the equestrian community. Horses can be black, chestnut, bay, dun, roan, palameno, appaloosa, and many more. Some resources for understanding coat colour are fun. Coat colour is an excellent first step towards identification because it highly visible from all perspectives.

Mary’s band, Kaimanawa Ranges circ. 1994-98 – a diversity of coat colours.

How variable coat colours are will depend on how many breeds contributed to the feral population. In the Kaimanawa Ranges, for example, breeds used by the military and local farms, and both riding and pack horses during the regions colonisation by largely British immigrants contributed at different times to the feral population and so coat colour is moderately diverse. Coat colour variation is less variable in other populations, particularly those in Europe managed as ancient breeds. Coat colours are more variable in other populations, especially populations in North America that resulted from releases of horses at different times by a diversity of European colonists.

White face markings described. Source: Canadian Food Inspection Agency, www.inspection.gc.ca

Fortunately, even horses in populations with limited coat colour variation can be distinguished by highly variable patches of white hair on their face and feet. These too have a ready-made official and richly descriptive language. White markings on the face might include a star, strip, snip or full blaze, depending on their position and extent, and occasionally faces are entirely white – a condition called ‘bald’. Chins may also be white, even if the face is not marked.

White markings on the face are a particularly useful second-step towards identification because even startled horses will turn to look at a researcher.

For horses without white facial markings, the position of the hair whorl – also called a cowlick, swirl, crown, or trichoglyph – might be helpful. The hair whorl results from variation in the direction that short air grows and most horses have a hair whorl on their face. Again there is a rich vocabulary describing small differences in whorls. Most are not useful for identifying wild horses from a distance – being often small – but the position and shape of larger hair whorls might be useful because they can be low or high on the face, and variously circular or linear.

Basic white leg markings described. Source: Canadian Food Inspection Agency, www.inspection.gc.ca

White leg markings add considerably to the variety of identifying marks, especially because marks on different legs are seldom the same. It is rare for the leg to be white if the foot is not and so white markings on the feet are most often described by the height of the mark. Only the heel or coronet (the band of hair circling the hoof) might be white, or the mark extend upwards above the hock – progressively described as a pastern, fetlock, sock, and stocking. For a few horses, white patches on flanks and belly can also occur. Some wild horses might also have feathered feet, especially if breeds of heavy (work) horses have contributed to the population.

Marks on legs, although more variable than facial markings or coat colour, are usefully a third step towards identification because lower legs are sometimes not visible in tall vegetation and certain identification, if leg markings alone are used, might require seeing more than one leg.

Other rarer types of natural variation in a horses’ appearance can be useful such as scars, or indentations in the muscle – called dimples, especially if they occur in easy to view places like the face, neck, and flanks. These are seldom used in wild horse identification, however, because it is unlikely that the most difficult to distinguish individuals have them.

I have outlined only those marks that are permanent. The more often you see an individual the more you can rely on markings that might change. For example, distinctive tangles of hair in the mane or tail that might rip out, or overgrown or split hooves that might break off, would not be reliable features for identification if you did not see the horse frequently enough to know when the feature has been lost. They can, however, aid rapid identification if you are seeing the horse frequently.

An example of a horse identification card where unique markings on the face, legs and body can be recorded and described for future reference.

In long-term studies of wild horse populations descriptions and drawings of each horse’s colour and white markings should be made and catalogued for easy reference to prevent errors of identification. Electronic versions or physical copies might also accompany the researcher into the field site. Many existing formats are available and developed by government and equestrian groups and artists that can be simplified and adopted to your particular needs.

Using natural marks like these it is possible to identify almost all wild horses reliably and studies of large populations have been successfully conducted on this basis. Nevertheless, more rapid progress in studies of wild horse behaviour and ecology is made if artificial markings can also be applied. In a future post I will discuss the different types of artificial marking available and their advantages and disadvantages for wild horse studies.

The time before people had horses

Horses transformed human societies. The domestication of the horse, more than any other animal, altered the trajectory of our species – accelerating knowledge, resource and cultural exchange and conflict, leading to cycles of technological revolution [1]. And yet…, ironically, we almost exterminated them all.

 Twenty thousand years ago, in the midst of our planets last ice age, perhaps one million or so modern humans like you and me were living as hunter-gatherers. They had no domestic plants or animals – relying entirely on what they could win from a biologically diverse wilderness for survival. They hunted horses… and a number of other large herbivorous mammals besides.

Palaeolithic people hunting horses and aurochs at Olga Grande, Portugal. Source: artist Marcos Oliveira, http://donsmaps.com/coavalley.html.

From 20,000 to 12,000 years ago northern Europe and Asia were dominated by the mammoth fauna, including bison, rhinoceros, horse and reindeer. In some places our species were relatively sedentary and made shelters of mammoth bones, tusks and hides. In the south we were more nomadic and followed migrating herds of horses and reindeer. Our late-Palaeolithic ancestors drove horses up against rocks or into corrals – helped by commensal dogs –  and slaughtered them with spears [2]. Horses roamed Eurasia in enormous numbers. Their broken remains after slaughter and consumption are common where Palaeolithic people lived.

Paintings of mammoths, a horse, and a rhincoeros by Palaeolithic people in Kapova Cave, Burzyanskiy, Republic of Bashkortostan, Russia. Source: http://donsmaps.com/kapova.html. Photo by Ivan Shkalikov via Panoramio.

Planet temperature rose by a staggering 7 degrees Celsius after the final cold-snap of the ice age – called the Younger dryas 12,800 to 11,500 years ago – rapid climate change. Forests advanced over Europe’s receding steppe and the ice-age mega-fauna of gigantic mammoths and woolly rhinoceros retreated to the still cold and far reaches of northern Europe and Asia to finally disappear between 8,000 and 3,800 years ago. Horses still lived in parts of Eurasia but in smaller herds.

It is unknown what contributed most to the mammoth fauna’s collapse and the final demise of the wild horse over most of Europe and Asia – climate and habitat change or hunting – probably a combination. It is certain, however, that we hunted horses and the Eurasian wild horse is now extinct.

But then, sometime, just before extinction took the last Eurasian wild horse, some were domesticated.

Today we seven billion people and our few domestic animal species, a fragment of the planets vertebrate biodiversity, populate the world. Together we are the majority – a staggering ~97% – of the world’s land-living vertebrate biodiversity by weight (biomass) [3]. The 65% of vertebrate biomass attributable to domestic stock is made up largely of the five big herbivores- sheep, goats, pigs, cattle and horses [1].

Horses transformed the relationships of our species races and cultures. The forty metre tall statue of Genghis Khan on horseback, Tov Province, Tsonjin Boldog, Mongolia. Source: http://www.mongolia-attractions.com/genghis-khans-riches.html

Horses were domesticated last of the ‘big-five’ domesticates but are most responsible for the composition, distribution and relationships of our species races and cultures today. Horses transformed agriculture, industry, medicine, communication, and conflict because they were adaptable as beasts of burden, for food and clothing, and more rapid transportation. Almost 60 million horses again populate our planet – check out the informatoin available from the Food and Agriculture Organisation (FAO) of the United Nations.

There is a lesson our relationship with horses for the conservation of other species and their habitat. A few domestic survivors of the horse – an animal we exploited to extinction in the wild – became fundamental to advances in the quality of our lives. How many species extinctions since were, or in the future will be, plants and animals with yet unrealised potential to make our lives better?

In future posts under the category ‘People & Horses’ I will explore the relationship between our species and the horse, beginning with what we know about how they were domesticated and the consequence of that new relationship for both our species.

Bibliography

1 Guns, Germs, and Steel. Diamond, J. (1999) W. W. Norton & Company, Inc.

2 Animals as Domesticates. Clutton-Brock, J. (2012) Michigan State University Press

3 Eating Our Future: The Environmental Impact of Industrial Animal Agriculture. Appleby, M. (2008) World Society for the Protection of Animals

The problem with a P-centric world

10 disadvantages of null-hypothisis testing:
1. The alternative hypotheis is not evaluated,
2. The null hypothesis is uninformative, often ridiculous (e.g., males and females are different – duh!)
3. It assumes asymptotic distributions,
4. It assumes thresholds of ‘evidence’, but
5. A P-value is not evidential, and
6. A P-value is not a strength of evidence, 7. The world is not explained by single models, 8. A null-hypothesis test has no ability to add and quantify model selection uncertainty, and 9. No ability to deal with large systems or datasets, and, lastly, 10. It has proven to be unuseful in a court of law!

ConservationBytes.com

Quite some time ago I blogged about a ‘new’ book published by Oxford University Press and edited by Navjot Sodhi and Paul Ehrlich called Conservation Biology for Allin which Barry Brook and I wrote a chapter entitled The conservation biologist’s toolbox – principles for the design and analysis of conservation studies.

More recently, I attended the 2010 International Meeting of the Association for Tropical Biology and Conservation (ATBC) in Bali where I gave a 30-minute talk about the chapter, and I was overwhelmed with positive responses from the audience. The only problem was that 30 minutes wasn’t even remotely long enough to talk about all the topics we covered in the chapter, and I had to skip over a lot of material.

So…, I’ve blogged about the book, and now I thought I’d blog about the chapter.

The topics we cover are varied, but we really only deal…

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A beginning

The air is so clear. The distant hills are close with me. Looking around I feel like I am everywhere at once in the river basin below. Clean lines of brown-greens, grey-blues and living blacks peppered with snow turn me inside out into this landscape.

Argo River Basin, Kaimanawa Ranges and army training area, east of Waiouru township after light snow, late-winter 1994.

Deep cloud hugs these high lands today. I live in the narrow space between. The ceiling of cloud is penetrated occasionally by the sun illuminating groups of horses spread over hillsides. Relaxed, they take best advantage of the first warm rays in days.

Like a visitor in a new place, everyone looks the same to me. All horses are brown, but then also black-brown or yellow-brown. Then some have white socks and some have blazes. Patterns of colour and imperfection are who they become to me. But it takes a long time to distinguish and learn the many patterns. Some horses, though, still look the same, especially from a distance. They also flee at my approach – galloping around or over a ridge from view before I can identify or describe their pattern.

Freeze brand ’63’ on right croup of mare. A muster in July 1994 gathered and branded 139 horses 1 year of age or older prior to the start of the study.

Fortunately, numbers also mark my horses. The wild horses of Argo Valley were mustered by stockmen on horseback, motorcycle and helicopter and freeze-branded just five weeks ago. Two large (8 X 5 cm, 3 X 2 in), new, and white numbers are beginning to reveal themselves to me on each horse’s right rump (or croup) as hair from patches shaved to receive the branding iron grows back. White hair grows back over the brand slowly but after three weeks we are starting to read numbers. In late-August 1994 we read our first freeze-brand, 6 over 4, on a mare and call her Vicki. Brands 47 and 6 over 0 follow. Within three months all brands are clear outstanding numbers. We name our first band (breeding group) Ali’s band, then Mary’s band. By mid-October we had seen over 100 brands and were seeing many each day. Eventually with brands and natural marking we would reliably identify 455 horses.

Army training zones are my guide as I move about the study area in search of horses. Military lines on a map that tell me where I can go and where I cannot because soldiers are being trained, vehicles manoeuvred, and weapons tested. A snow drift at the end of Zone 29c halts my progress up Maowhango Bridge Road. I am surprised by horses with freeze-brands in Zones 27, 21 and even 17 and 18. There is army activity in Zone 30. I cannot go there – but I can peer into it from the hillock in Zone 28. My landscape is a colour-by-numbers for a palate of horses branded with numerals I do not yet know. I am an amateur again – re-learning colours and numbers.

Viewing Mount Ruapehu from the central volcanic plateau and southern Kaimanawa Ranges east of Waiouru Township. We negotiated greater distances on an all-terraine vehicle in our search for branded horses early in the study.

I would spend most of each month for the next four years roaming the ridges and valleys of military zones on foot or all-terrain vehicle. The foreign would become familiar – landscape and climate. Wild horses identified would became characters in my study of their behaviour and ecology. Not before a ‘horse lover’, I would become one. Scientific discovery was my path to an appreciation of horses and other Perissodactyla. But for the moment this was just a beginning. I was excited but nervous – naïve about what the next four years would bring.