…or, why is foaling by 2-year-olds not more common.

(image source: http://www.thehorse.com)

Young, still growing, mares face greater challenges to succesfully foaling (image source: http://www.thehorse.com)

Our transition from child to adult is a fraught with physical and mental challenges, made worse by our inexperience. We are less able, when our life’s challenges are greatest. Its tough being a teen.

For horses the transition to adulthood occurs from about just before their first birthday through their second year and, for some, into the beginning of their 3rd year. Compared to people, horses (and most other animals), mature up quickly.

A demanding, vulnerable time

Young mares are naive and still investing into growing their bodies. Their inexperience at competing for resources, like food and shelter, and protecting themselves from risks, like aggressors, competitors and predators, makes them vulnerable.

They have not yet formed protective relationships with other mares [1] and a stallion [2] in a breeding and social group called a band. They will, at some time during their teens and probably around their first oestrus, leave their mothers band for another – called natal dispersal [3].

During their teens they may move often between bands – called social dispersal [3] - where they will be more attacked and harassed by other mares, stallions, and bachelor males than at any other time in their lives. It is a high-risk period and the consequences are reproductive failure.

Reproductive delay

The challenges of maturing and growing can delay a mares first foaling and makes rates of reproductive failure higher in younger mares such that foaling rates rise as mares age into their middle years.

Mares are capable of conceiving as soon as they reach sexual maturity around 1 year and, therefore, foaling as a 2-year-old but more commonly they will foal for the first time as 3-, 4-, or 5-year-olds because the physical, cognitive (mental), and social demands of maturing place great demands on them.

Young mare foaling rates measured

The age that mares first breed and foaling rates of young mares have been measured in only a handful of studies where frequent observations have meant that mare birth dates were known and their subsequent foals found.

On Assateague Island National Seashore no 2-year-olds foaled but 23% of 3-year-olds did and from their foaling rates increased up to 69% in 6-year-olds [4]. Similar values with mare age are reported from Nevada, and Cumberland Island, Georgia [5, 6] (see accompanying graphic).

young mare foalingStallions impact on young mare breeding?

The pattern of climbing foaling success was very different in the Pryor Mountain population [7] because, although 2-year-olds did not foal and older mares had comparative low foaling rate, 3-year-olds had a substantial foaling rate – almost identical to the extraordinary foaling rate of 3-year-olds in Joel Berger’s erupting population in the Granite Range, Nevada [8].

I suspect that this difference reflects the extremely mare-biased adult sex ratio due to stallion removals from that population. Where there are substantially fewer stallions, the costs of social dispersal and sexual harassment for 1- and 2-year-old mares breeding for the first time might be substantially reduced. Sexual and social competition have consequences, especially during dispersal for first-time breeders.

Teen pregnancy in Nevada

The magnitude of the eruptive reproductive rates that Joel Berger observed in the Granite Range, Nevada (1979-93) are best revealed when plotted for comparison against other populations [8]. Not only were 2 year olds foaling, but all mares 2 years old and older were foaling at the highest rates ever reported. A remarkable 86% of mares foaled in their sixth year.

The extraordinary foaling rates to a suite of historical events, but particularly the removal of cattle – a competitor of horses – combined to improve the amount and quality of food (grass) available to the Granite Range population.

Kaimanawa mare foaling unremarkable

Although many claimed that Kaimanawa population was undergoing eruptive growth like the populations described in the Granite Range, and Jackie’s and Beaty’s Butte, Oregon, the data on foaling rates by mares did not support those claims [9].

The graphic serves to show how unremarkable foaling rates by young mares in the Kaimanawa Ranges were compared to other populations. Foaling rates by 3 and 4-year-olds were year olds were low compared to all except the Cumberland Island population, Georgia [6].

Interestingly though, in 1998 a single two-year-old foaled – the first and only one to do so. Was this an indication of improved range conditions because musters had reduced horse densities?

Bibliography

1. Cameron, E. Z., Setsaas, T. & Linklater, W. L. Social bonds between unrelated females increase reproductive success in feral horses. Proceedings of the National Academy of Sciences of the United States of America 106, 13850-13853 (2009).

2. Linklater, W. L., Cameron, E. Z., Minot, E. O. & Stafford, K. J. Stallion harassment and the mating system of horses. Animal Behaviour 58, 295-306 (1999).

3. Linklater, W. & Cameron, E. Social dispersal but with philopatry reveals incest avoidance in a polygynous ungulate. Animal Behaviour 77, 1085-1093 (2009).

4. Keiper, R. & Houpt, K. Reproduction in feral horses: An eight year study. American Journal of Veterinary Research 45, 991-995 (1984).

5. Siniff, D. B., Tester, J. R. & McMahon, G. L. Foaling rate and survival of feral horses in Western Nevada. Journal of Range Management 39, 296-297 (1986).

6. Goodloe, R. B., Warren, R. J., Osborn, D. A. & Hall, C. Population characteristics of feral horses on Cumberland Island, Goergia and their management implications. Journal of Wildlife Management 64, 114-121 (2000).

7. Garrott, R. & Taylor, L. Dynamics of a feral horse population in Montana. Journal of Wildlife Management 54, 603-612 (1990).

8. Berger, J. Wild horses of the Great Basin. (University of Chicago Press, 1986).

9. Linklater, W. L., Cameron, E. Z., Minot, E. O. & Stafford, K. J. Feral horse demography and population growth in the Kaimanawa Ranges, New Zealand. Wildlife Research 31, 119-128 (2004).

For many years during the early, vigorous debates about how fast wild horse populations could grow, the ability of younger mares to foal, especially 2-year-olds, was unknown. The first few studies found that 2-year-olds did not foal and so it was believed unlikely.

Even in the Chincoteague Ntional Seashore, a population with comparatively high reproductive rates at ? foals for every other horse, 2-year-olds were not reported to foal (image source: )

Even on the Chincoteague Island, a population in which mare foaling rates were the highest reported (74% during 1975-82), 2-year-olds were not reported to foal (image source: http://a-glo.com/Wildlife/wildlife51.htm).

The first few studies of wild horse demography, by Ronald Keiper on Assateague Island (1975-79) [1] and Lee Boyd from Wyoming’s Red Desert (1978-79) [2], found no 2-year-olds foaled.

Even in populations like Chincoteague (1975-82), with the highest foaling rates reported, no 2-year-old mares foaled.

Pregnancy testing wild mares

The early development of pregnancy testing by radioimmunoassay and its application to wild mares mustered from their range also found no evidence for 2-year-old foaling.

From three places near Salmon, Idaho, during October, 1980, musters removed about half the horses – 300 horses all together including 137 mares – but found no evidence of pregnancy in 1-year-olds or lactation by 2-year-olds [3].

Mares most often foal for the first time as 3- or 4-year-olds and some older still, having become pregnant as 2-year-olds. Nevertheless, yearlings can also successfully conceive and foal s 2-year-olds (image source: www.wildhorsepl.org/mustangs).

Mares most often foal for the first time as 3- or 4-year-olds and some older still, having become pregnant as 2-year-olds. Nevertheless, yearlings can also successfully conceive and foal as a 2-year-olds (image source: http://www.wildhorsepl.org/mustangs).

First-foaling as a 3-year-old was the norm

During the early years of the debate, however, high population growth rates were being calculated from sequences of population counts.

Counts from Beaty’s Butte and Jackie’s Butte during the 1970s indicated a 20-22% average annual increase [4].*

Similar, but probably less reliable count sequences, led to reports such as:

During the past 3 years it has been estimated that wild horse numbers are increasing at an estimated rate of 20-30% each year” [5] – C. Wayne Cook: Rangeman’s Journal, 1975

To achieve population growth of this magnitude, high foaling rates, especially by younger mares, were expected but not being supported by demographic evidence from the better studied populations.

From Assateague Islands and Chincoteague (1975-82) [1, 6], and the deserts of Wyoming (1978-79) [2] and Nevada (1980-82) [7], mares foaled for the first time only as 3-year-olds and most in all populations did not foal until they were 4 or 5 years old. Two-year-olds did not foal.

But then came Joel Berger’s landmark fieldwork in the Granite Range of Nevada during the early 1980s [8]. It changed our minds entirely.

Joel Berger's 1986 book - amongst the first to identify comparatively high reproductive rates amongst 2- and 3-year-old mares.

Joel Berger’s 1986 book – amongst the first to identify comparatively high reproductive rates amongst 2- and 3-year-old mares.

Teen pregnancy, Nevada

From 1979 to 1983 Joel Berger followed a population that was 58 at the beginning of his study.

He discovered extraordinary foaling rates, especially in younger mares foaling for the first time.

About 37% of 2-year-olds and 40% of 3-year-olds foaled. Given that 2-year-olds that foaled are unlikely to have foal again as 3-year-olds, these figures indicate that about 80% of mares foaled for the first time as 3-year-olds or younger. Suddenly, the capacity for rapid population growth was understood.

During the five years of the study, the Granite Range population grew by 91 horses to 149 – an instantaneous rate of increase (r) of 0.188 or a finite rate of increase (lambda, λ) of 1.21. In other words, the population had an average annual increase of 21% **. Clearly, two-year-old foaling in large numbers was possible.

Young mare foaling and eruptive growth

Joel’s work explains how some populations of horses can undergo, what is called, eruptive growth – short periods of maximum reproduction and survival leading to rapid population growth.

It is clear that for short periods of time, such as 4-5 years, extraordinarily high rates of first time foaling by 2- and 3-year-olds can translate into population growth that just exceeds 20% per annum. Importantly however, the population growth that Joel observed did not approach the earlier alarmist reports of growth rates up to up to 30% per annum [5].

Joel’s work linking first-time foaling rates and rapid population growth is exceptional and a useful insight into the largest growth rates possible for wild horse populations. Nevertheless, many subsequent studies would continue to demonstrate that in other places 2-year-old foaling was uncommon.

In similar North American studies on Pryor Mountain (1976-86) [9] and Cumberland Island (1986-90) [10], in the mountains of New Zealand (1994-98) [11], and grasslands of Argentina (1995-2002) [12], 2-year-old foaling either did not occur or was rare.

If 2-year-old foaling is possible and can occur at high rates, then why wasn’t it more commonly found?

Or, if 2-year-old foaling is more common than studies have detected, why is rapid population growth not more common?

- topics for subsequent posts.

Footnotes

* Eberhardt, Majorowicz & Wilcox (1982) has been repeatedly used as supporting evidence of high population growth rates in wild horse populations but the authors were careful to write “We do not propose that these herds are necessarily typical of feral horses in general”. It should not be assumed that the high growth rates reported by Eberhardt, Majorowicz & Wilcox are ubiquitous, only possible.

** In Joel Berger’s book (P76) the average finite rate of increase is written as 31%. This is incorrect and probably a printing error that should have read 21%. A 31% rate of increase would have generated 225 horses from 58 over the study period, not the 149 horses that were alive at the end of the study.

Bibliography

1. Keiper, R.R. (1979) Population dynamics of feral ponies. In Symposium on the ecology and behavior of feral and wild equids (Denniston, R.H., ed), pp. 175-183, University of Wyoming, Laramie.

2. Boyd, L. (1979) The mare-foal demography of feral horses in Wyoming’s Red Desert. In Symposium on the ecology and behavior of wild and feral equids (Denniston, R.H., ed), pp. 185-204, University of Wyoming, Laramie.

3. Seal, U.S. and Plotka, E.D. (1983) Age-specific pregnancy rates in feral horses. Journal of Wildlife Management 47, 422-429.

4. Eberhardt, L.L., et al. (1982) Apparent rates of increase for two feral horse herds. Journal of Wildlife Management 46, 367-374.

5. Cook, C.W. (1975) Wild horses and burros: a new management problem. Rangeman’s Journal 2, 19-21.

6. Keiper, R.R. and Houpt, K. (1984) Reproduction in feral horses: An eight year study. American Journal of Veterinary Research 45, 991-995.

7. Siniff, D., et al. (1982) Wild Horse Survival and Foaling Rates: Final Report to BLM (Contract AA851-CTO-52). University of Minnesota.

8. Berger, J. (1986) Wild horses of the Great Basin. University of Chicago Press.

9. Garrott, R. and Taylor, L. (1990) Dynamics of a feral horse population in Montana. Journal of Wildlife Management 54, 603-612.

10. Goodloe, R.B., et al. (2000) Population characteristics of feral horses on Cumberland Island, Goergia and their management implications. Journal of Wildlife Management 64, 114-121.

11. Linklater, W.L., et al. (2004) Feral horse demography and population growth in the Kaimanawa Ranges, New Zealand. Wildlife Research. 31, 119-128.

12. Scorolli, A.L. and Cazorla, A.C.L. (2010) Demography of feral horses (Equus caballus): a long-term study in Tornquist Park, Argentina. Wildlife Research 37, 207-214.

- pressed from original post at http://sciblogs.co.nz/politecol/

Resurgent killing for horn that is then traded on the international black market for thousands of dollars a gram threatens to undo two decades of progress recovering the black rhinoceros from near extinction. Countries are mobilising and people are dying protecting rhino from international crime syndicates that out manoeuvre and out gun them. Do not underestimate our situation – we at war for biodiversity and the environment.

In this context the sale of a permit to hunt a black rhino in Namibia for US$350,000 at the Dallas Safari Club created a mad furore. For many, especially of the well-to-do, comfortable, urbanites of the West, conservation hunting is oxymoronic.

Neto - field assistant and rhino ranger - and I shelter behind tree trunks as Alice mock charges. Black rhino, when not frightened away, can be aggressive towards people and so make themsleves as easy, and thrilling, target for hunters.

Neto Pule, field assistant and rhino ranger, and I shelter behind tree truncks as Alice mock charges. Black rhino can be aggressive towards people and so make themselves easy, and thrilling, targets for hunters. See also the video of a rhino charing below.

But we should try to achieve a more considered and carefully articulated response to this event than the one heard from many individuals and groups who claim the mantle of animal rights or conservation in our first-world countries.

Some conservation organisations, like the International Union for the Conservation of Nature, and the US Fish & Wildlife Service, support the hunt. Why would they?

On my way to answering this question, let me begin with my experience of stalking rhino.

Hunting rhino is easy

It is not difficult to shoot a rhinoceros – thousands of successful poachers and the near extinction of the species attest to that. They can be dangerous, of course. Regrettably, I have seen how dangerous rhino can be and I don’t wish to revisit the images seared into my brain that still wake me some nights. But rhino are also very vulnerable to a bullet.

In my work with black rhino I have been close enough to shoot over 100, and I am not a practiced shot. But black rhino make the task easy. They leave their heavy, easily followed, tracks from waterholes where they must drink each day. They are terribly poor sighted – relying on their sense of hearing and smell to detect danger – and so I have routinely stalked rhino to within 30 metres downwind without being detected.

How close can you get?

One of the students in my research group, Roan Plotz, who recently finished his PhD, measured how quickly a black rhino detects a person walking towards it by asking his field ranger and assistant to walk crosswind, without concealment, directly at black rhino. The black rhino failed to detect 77% of approaches before Roan had to call off the approach out of fear for the field ranger’s safety. Even when detected, the field ranger first got to within 23m of the black rhino (59m if there are oxpecker birds on the rhinos back, but that is another story for another time).

We had been watching this adult female rhino for over 20 minutes undetected. But then she smelt or heard us. I am unsure which. She turned towards us to investigate, paused for what seemed several minutes, but then charged. This was not a mock charge. Snorting as she ran at us, she hit the other side of the tree trunk with her horns and full weight - more than 1 tonne. I felt the tree move and almost droped the camera

Rhinos’ death-wish behaviour

If disturbed by the smell or sound of danger – a snapping twig, a scent of human – rhino lift their heads and turn to face the danger, thus providing the perfect forehead shot. They will flee if they detect people, but not always. Sometimes they will approach to confirm the danger. Sometimes they will charge, but often only to threaten.

I have stood behind many a tree trunk with a black rhino 2 or 3 car lengths away having halted its charge, and occassionally even within arms-reach as it pounded the other side of the tree with its horn. My field ranger could have rested the loaded barrel of his rifle against the rhinos’ forehead.

All of these behaviours provide the hunter of black rhino ample opportunity for a well-placed bullet. White rhino are even easier to kill. They are social and prefer to eat grass, and so live in small groups and more open habitat with better visibility for the stalker.

Hunting as part-solution

Nevertheless, some find the power and prestige, or mana as we call it in New Zealand, of killing a rhino with modern weaponry an achievement. And, against my experience, I accept their preferences as another example of the diversity of human approaches to our natural world because hunters can play a small but important role in the conservation of endangered species like rhino.

Solutions to the extinction crisis come in many forms. I wager that there are almost as many parts to the solutions as the people contributing to them. I am not a hunter. But I am a rhino conservationist. The evidence leads me to believe that they can sometimes the same thing.

I’m unlikely to ever want to kill a rhino. But, here – in the following posts of this series – I will defend rhino hunting as an appropriate, useful, and important contribution to species conservation.

It will be a journey in ecology, economics, and social psychology, not of rhino, but of people.

Ponies in Chincoteague National Wildlife Refuge (Image courtesy of TripAdvisor http://www.tripadvisor.com)

Chincoteague National Wildlife Refuge, during the late 1970s [1, 2], yielded an average 74% of mares foaling each year – the highest average rate ever reported.

The lowest average reproductive rate is reported from the Elcana Range, Nevada, from 1989 to 1998 when just 36% of mares foaled each year [3, 4].

All other populations have mare reproductive rates that fall between these two extremes. And so it is typical for around half of all mares of reproductive age to foal each year with some variation between populations (see the table below). Rates greater than 65% are comparatively high, and rates less than 50% are comparatively low.

No population is the same…

Large variation, therefore, exists between populations in reproductive rates and their capacity to grow. Most variation between populations is likely driven by the fundamental characters of their Table adult mare foalinglocations – their topography and climate – and the influence of those on the quantity and quality of food and shelter, and ease-of-access to water. Some places are just nicer and easier to live and breed.

… even from year to year

It is also evident from the accompanying table, however, that variation in annual reproductive rates from year to year for the same sites are greater than the spread of values between sites, due to annual changes in range conditions.

Range conditions can improve or deteriorate dramatically between years because they are driven by both changes in climate and animal density – food and shelter, and competition for them.

The high reproductive rates on Chinocoteague [1, 2], for example, were probably facilitated by the annual live harvest from the population that occurs to this day and reduces competition amongst horses for grazing.

The annual muster and swim of the Chincoteague ponies (image courtesy of The Baltimore Sun http://www.baltimoresun.com).

New Zealand’s wild horses in the Kaimanawa Mountains (highlighted in the Table) mares had comparatively moderate foaling rates averaging 55% during the late 1990s and so sit squarely between the extremes reported [5].  Nevertheless, the substantial population reductions that have occurred since this time are likely to have elevated reproductive rates.

It is likely that average, and especially single annual [6], rates could be found that are lower than the values shown – extreme climatic events or disease might result in some very poor foaling rates in some years. But it is much less likely that new higher values will be found. Individual annual rates exceeding 81% and average rates of around 75% are probably at or near the largest possible given the inherent constraints on mare reproduction.

These real-world values are a useful insight informing our conversation about population growth and what is and is not possible or claims credible.

The question of 2-year-olds foaling

In this post, I have considered only mares 3 years old and older as adult (reproductive age) because most studies, including those represented in the Table above, report that 2-year-olds did not foal. Nevertheless, in a few populations 2-year-olds do foal with potentially important consequences for population’s capacity to grow.

Does earlier-age  foaling elevate a population’s reproductive rate or are younger, still growing mares so exhausted by raising their foal that they are unable to foal again for several years?

I will address reproductive rates of 2-year-old and their adult mare populations next.

Bibliography and notes

1. Keiper RR. 1979. Population dynamics of feral ponies. In Symposium on the ecology and behavior of feral and wild equids; University of Wyoming, Laramie. Edited by Denniston RH. University of Wyoming, Laramie; 175-183.

2. Keiper R, Houpt K. 1984 Reproduction in feral horses: An eight year study. American Journal of Veterinary Research, 45:991-995.

3. Greger PD, Romney EM. 1999. High foal mortality limits growth of a desert feral horse population in Nevada. Great Basin Naturalist, 59:374-379.

4. I have not used values from studies where only one year of data is available because they are much less likely to represent the population average. For example, Kirkpatrick and Turner (1991) [6] reported 32.5% of mares foaling in 1990 on Assateague Island National Seashore.

5. Linklater WL, Cameron EZ, Minot EO, Stafford KJ. 2004. Feral horse demography and population growth in the Kaimanawa Ranges, New Zealand. Wildlife Research, 31:119-128.

6. Kirkpatrick JF, Turner JW. 1991. Compensatory reproduction in feral horses. Journal of Wildlife Management, 55:649-652.

7. Garrott R, Taylor L. 1990. Dynamics of a feral horse population in Montana. Journal of Wildlife Management, 54:603-612.

8. Scorolli AL, Cazorla ACL. 2010. Demography of feral horses (Equus caballus): a long-term study in Tornquist Park, Argentina. Wildlife Research, 37:207-214.

9. Goodloe RB, Warren RJ, Osborn DA, Hall C. 2000. Population characteristics of feral horses on Cumberland Island, Goergia and their management implications. Journal of Wildlife Management 2000, 64:114-121.

10. Boyd L. 1979. The mare-foal demography of feral horses in Wyoming’s Red Desert. In Symposium on the ecology and behavior of wild and feral equids; University of Wyoming, Laramie. Edited by Denniston RH. University of Wyoming, Laramie; 185-204.

The ratio of foals to other horses, or foals as a percentage of total population, are comparatively easy to gather and interpret reproductive rates that have a direct relationship to how much a population grows or declines each year (lambda, λ) and the population’s instantaneous rate of increase or decrease (r). Averaging and comparing reproductive rates over several years and how they vary from year to year provides insight about the potential of populations to grow.

Reproductive rates from Jackie’s and Beaty’s Buttes from 1969 to 1980 are amongst the highest and most variable reported. Around 26 foals for every 100 other horses was the average annual rate and it ranged from 15 to 39 foals for every 100 other horses in different years (image source: http://www.blm.gov).

The most extraordinary foaling rates with equally extraordinary variability between years are reported from Jackie’s Butte and Beaty’s Butte, Oregon. Foals to other horse ratios averaged 0.27 and 0.25, respectively, and ranged from 0.19 to 0.39 in Jackie’s Butte, and 0.22 to 0.30 in Beaty’s Butte, from 1969-80 [1]. Thus, foaling rates ranged up to 30% below to 44% above the 12-year average.Similarly high rates are reported from the Red Desert, Wyoming [2], where the foals to other horse ratios were 0.295 and 0.217 in 1978 and 1979, respectively (average 0.256).

Moderate foaling

Foaling rates were not nearly as high in other places but still highly variable from year to year. From 1990 to 1994, in the Elcana Range between the Mohave and Great Basin deserts, at a place better known for being Nevada’s nuclear weapons test site [3], foal to other horse ratios averaged 0.196 and ranged from 0.148 to 0.262, or from 25% below to 34% above the 5-year average [4]. In the Tornquist Park population, Argentina [5], the ratio is not presented but I was able to calculate it for 1995 and 2002 because population counts for those years are also given. Similarly, the foal to other horse ratio was 0.196 and 0.21 for those years.

…even though they had mare-biased sex ratios

Foaling rates on the Pryor Mountain Wild Horse Range from 1976 to 1986 averaged 0.189 and, although reported to be high [6], can be seen here to be moderate. Indeed, the reproductive rate was inflated by

Horses of the Assateague Island National Seashore (1975-79), like the Pryor Mountain herd around the same time, had twice as many mares as stallions but comparatively moderate reproductive rates less than 0.20 foals for every other horse, although a higher ratio of mares to stallions will elevate population-level reproductive rates (image source: tlc.howstuffworks.com).

an adult sex ratio biased towards mares. There were twice as many mares as stallions due to a history of removals that were selective of males. If managers had preserved an even ratio of adult mares and stallions the population would have reproduced itself at a much lower rate.

There were also over twice as many mares as stallions on the Assateague Island National Seashore (2.1 mares per stallion) when Ronald Keiper, Pennsylvania State University, investigated the population dynamics of its introduced horses during the late-1970s. Nevertheless, those rates too were moderate at 0.198 foals per other horse [7].

When comparing reproductive rates it is important to check for distortions in adult sex ratio away from male-female parity (that is equal in number). Stallion-biased sex ratios will suppress, and mare-biased ratios inflate, population-level reproductive rates like those presented here.

Lower foaling rates

Other places had much lower foaling rates. The foaling rate in Stone Cabin Valley, Nevada, during 1975 and 1976 was 0.12 and 0.18 foals for every other horse [8]. Similarly low rates of 0.15 to 0.19 between 1986 and 1990 also occurred on Cumberland Island, Georgia (USA) [9]. Examples of populations with lower reproductive rates appear to be less often written about although they must occur. One would expect a scientific publication bias towards populations with higher reprodcutuve rates where population impact and control, not conservation, has been the motivation for research.

More detailed demographic studies

Unfortunately, most other more detailed demographic studies are more difficult to interpret for comparison because they report the foaling rate as a percentage of adult mares foaling and define the age a mare is adult differently. Some define all females 3 years old and older as adult mares, while others consider 2-year-olds also adults.

This difference in how studies report foaling rate per adult female results because only a few populations report 2-year-olds foaling [10]. In most populations 2-year-olds were not reported to foal and so were excluded from calculations.

Joel Berger's 1986 book - amongst the first to identify comparatively high reproductive rates amongst 2- and 3-year-old mares.

Joel Berger’s 1986 book – amongst the first to identify comparatively high reproductive rates amongst 2- and 3-year-old mares.

Joel Berger reported 37% of 2-year-olds foaling in the Granite Range, Nevada [10], and was the first to find substantial foaling by young mares and so explain why some feral horse populations could grow more rapidly. Because the rate at which 2-year-olds foal may be critical to rapid population growth I will devote a post to two-year-old foaling rates later.

Upper limits to population growth

Studies report, therefore, from 15 to almost 30 foals per 100 other horses and so help define the upper limits of population growth. A population cannot grow 30% or more over several years if each year it averages fewer than 30 foals per 100 other horses each year.

For the moment, reports of the ratio of foals to other horses in populations indicate that their average growth rate should not exceed 27% per year and can vary considerably – by as much as 110%  between years and from 30% below to 44% above the long-term average.

Bibliography

1. Eberhardt, L.L., Majorowicz, A.K., Wilcox, J.A. 1982: Apparent rates of increase for two feral horse herds. Journal of Wildlife Management 1982, 46: 367-374.

2. Boyd, L. (1979) The mare-foal demography of feral horses in Wyoming’s Red Desert. In Symposium on the ecology and behavior of wild and feral equids (Denniston, R.H., ed), pp. 185-204, University of Wyoming, Laramie.

3. Nuclear explosions at Nevada’s nuclear weapons test site occurred above ground 1951 to July 62, and below ground until 1992.

4. Greger PD, Romney EM. 1999. High foal mortality limits growth of a desert feral horse population in Nevada. Great Basin Naturalist, 59:374-379.

5. Scorolli, A.L. and Cazorla, A.C.L. 2010. Demography of feral horses (Equus caballus): a long-term study in Tornquist Park, Argentina. Wildlife Research 37: 207-214.

6. Garrott R, Taylor L: Dynamics of a feral horse population in Montana. Journal of Wildlife Management 1990, 54:603-612.

7.Keiper RR: Population dynamics of feral ponies. In Symposium on the ecology and behavior of feral and wild equids; University of Wyoming, Laramie. Edited by Denniston RH. University of Wyoming, Laramie; 1979: 175-183.

8. Green, N.; Green, H. In The wild horse population of stone cabin valley, Nevada: A preliminary report, Proceedings of the National Wild Horse Forum, University of Nevada, Reno, 1977; University of Nevada, Reno, pp 59-65.

9. Goodloe, R.B.,Warren, R.J., Osborn, D.A., Hall, C. 2000. Population characteristics of feral horses on Cumberland Island, Goergia and their management implications. Journal of Wildlife Management 64, 114-121.

10. Berger, J. (1986) Wild horses of the Great Basin. University of Chicago Press.

As discussed in Sex and Magic: Tapir anthropomorphism, the tapir is a sacred animal whose place within these animist cultures can approach what those of us in the West would understand as  “anthropomorphized”.

While anthropomorphism is often used in a pejorative sense to describe a sentimental view of animals that lacks a certain sort of scientific objectivity, this blog post instead proposes reframing the issue through Eduardo Vivieros de Castro’s concept of the “multinatural”, developed in his ethnography of the Achuar people [1].

Despite originating from a different Amazonian ethnic group, the animist Nukak practice of building “the house of the tapir” serves as an example through which we can explore the potential application of “multinaturalism” to conservation practice, and contemporary ecology.

“the house of the tapir” from Nukak: Ethnoarchaeology of an Amazonian people.

“the house of the tapir” from Nukak: Ethnoarchaeology of an Amazonian people [1].

 

“The house of the the tapir” is a peculiar structure in that it “manifests the highest energy investment per architectural unit of all the structures built by Nukak” [2], yet is not meant to be inhabited by humans. In fact, it is relatively rare. Anthropologists posit that the “house of the tapir” serves as a refuge for the spirits, taking the form of the tapir, as they roam and graze the forest during the night.

While this this may be understood as a structure performing a sacred or merely symbolic function, it is not quite a temple in the conventional western sense of the word. It doesn’t quite translate as a “sacred site”, as it also serves as a place to to store tools, and rest while working cultivated garden areas or chagras, where the house of the tapir is often sited. Some suggest that it is in fact better understood as a replica or model –  “the house of tapir” is at once both the literal building seen in the photograph above, but also refers to an entire parallel spirit underworld.

The existence of such parallel spirit worlds are understood by some as a cornerstone to understanding an animist worldview, one in which the nonhuman environment contains a spiritual or supernatural essence. As an example, where a westerner may see a garden as a miniature forest, the Achuar may see the forest as a garden that is tended by spirits. This animation of the natural world provides a framework based on social kinship relationships, sitting in stark opposition to a naturalist worldview of the moderns [3]. Instead of projecting the static “laws of nature”  in an attempt to understand our social relationships, anthropologists suggest animist cultures project social structures onto the natural world.

These kinship relations differentiate themselves from anthropomorphization in that in a multinatural worldview, “the common point of reference for all beings of nature is not humans as a species but…humanity as a condition” [1].

As advances in behavioral science and ethology prompt us to reconsider the cartesian supposition of nonhuman animals as simple machines, elements of an animst worldview seem to come back into focus [4].

Whether or not you believe in spirit underworlds or nonhuman animals with souls,  understanding the natural world as a set of vibrant social relationships may in fact be a more useful than one which restricts sociality to intra-human relationships. In this way, “building the house of the tapir” becomes less of an anti-modern, anthropomorphic practice, and perhaps more about taking time to acknowledge the overlapping worlds we share with the beings around us.

Marcus Owens is trained as an architect and currently in the PhD program in Landscape Architecture at University of California Berkeley. His interests hover around, urbanism, development, multispecies ethnography and the production of public art and design. He was co-curator of “Multinatural Histories”, a contemporary art exhibition at the Harvard Museum of Natural History. Marcus Owens is trained as an architect and currently in the PhD program in Landscape Architecture at University of California Berkeley. His interests hover around, urbanism, development, multispecies ethnography and the production of public art and design. He was co-curator of “Multinatural Histories”, a contemporary art exhibition at the Harvard Museum of Natural History.Bibliography

Bibliography

[1] De Castro, Eduardo Viveiros. “Cosmological deixis and Amerindian perspectivism.” Journal of the Royal Anthropological Institute (1998): 469-488.

[2] Politis, Gustavo. Nukak: Ethnoarchaeology of an Amazonian people. Left Coast Press, 2009.

[3] Conan, Michel. “From vernacular gardens to a social anthropology of gardening.” Perspectives on Garden Histories. Dumbarton Oaks Research Library and Collection Washington, DC (1999).

[4] Lorimer, Jamie. “Multinatural geographies for the Anthropocene.” Progress in Human Geography 36.5 (2012): 593-612.

- the third in a series of guest-posts by students of Animal Geography at UC – Berkeley

Alice and the Dodo in Lewis Carroll’s Alice’s Adventures in Wonderland, a classic story with many anthropomorphic characters. The Dodo is the leader of the playful Caucus Race in which characters run in patterns of any shape to get dry, and everyone wins. The Race and its candidates, with such lack of clarity and decisiveness, is satire on the political caucus system. Original illustration is by John Tenniel.

Alice and the Dodo in Lewis Carroll’s Alice’s Adventures in Wonderland, a classic story with anthropomorphic characters. The Dodo is the confused and indecisive political leader of the playful Caucus Race where everyone wins – a satire on the political caucus system. Original illustration is by John Tenniel.

Wiley foxes and wise owls, deceptive snakes, and elephants with impeccable memory…

We all attribute human-like qualities onto animals. This phenomenon, called anthropomorphism, has deep roots in our perceptions of nature and the cosmos. Every society does it.

Perhaps you see a compassionate soul when you look into your dog’s chocolately-brown eyes, or an autonomous freethinker in your cat. But have you ever related a wild animal to your favourite sexual taboo?

Dreams, dinner, disease, and demons

There are three tapir species in the Americas. They are large rainforest mammals hunted by many indigenous peoples.

Amazonian and Amerindian folklore render tapirs as possessing human spirits and existing as powerful sex-symbols [1].

Tapirs are depicted as “oversexed demons [2] as well as “trickster-like” figures [1] with uncontrollable passion. Their sex is ambiguous – gender association varies by community – but tapirs are commonly portrayed as masculine “seducers of women” [1].

Perhaps the sizeable genitalia of the male tapir are anthropomorphized. Thus the animal is constructed as a wildly sexualised creature [3].

Lowland tapir species adult and juvenile. Illustrated by Stephen Nash. Source: www.tapirback.com

Lowland tapir species adult and juvenile. Illustrated by Stephen Nash. Source: http://www.tapirback.com

This mythic relationship between tapirs and humans surfaces in shamanistic dream interpretation and folklore. Besides sex, the topics most often associated with tapirs are hunting, food, and illness.

Among the Kagwahiv people of Brazil, a shaman’s dream of sexual organs forecasts the capture of a tapir because the tapir is an adulterer in mythology [4].

A story of the Peruvian Ashaninka people involves a woman who seduced a prominent local man and then transformed into a tapir. The man became ill and died soon after, and the myth evolved into a lesson about the consequences of indiscriminate sex [2].

A female Ashaninka shaman from the Peruvian Amazon. Source: http://vi.sualize.us

A female Ashaninka shaman from the Peruvian Amazon. Source: http://vi.sualize.us

Tukanoan shamans in Colombia ask ill patients about their dreams and what they have eaten. Patients’ dreams of threatening fauna, such as a giant tapir, are believed to reveal the disease as a consequence of over-hunting or broken food taboos [5].

Food is equated with sex: hunting and cooking are linked to mating by their association with pheromones and scent. Visions of tapirs signify the ill patient’s taboo sexual fantasies or disregard for the Tukanoan exogamic traditions [5].

A Nicaraguan Rama Indian narrative recounts the tale of a woman who runs away from her husband to live with a tapir, and together they produce a son. The loyal paramour provided sustenance for the woman until he was slain by her jealous husband. In this story, food and eating are again construed as a metaphor for copulation; the tapir is the only being that can truly satisfy the woman [6].

Who can resist this face? Source: www.irishmirror.ie

Who can resist this face? Source: http://www.irishmirror.ie

Plump, drooling, jungle beast: It’s what’s on the ‘inside’ that counts

For many from cultures with other perspectives, it may seem strange to associate a plump, drooling, jungle beast with human desire and sexuality.

During sex, however, humans are most like animals. It should come as no surprise that sexual behaviors are imposed onto animals in some societies.

Further, Amerindian and Amazonian shamanistic cultures generally consider animals as physically different but spiritually equal to humans. The souls of the spirit world embody and freely transform between humans, plants, and animals. These beliefs are derived from dominant animism ideology that shapes Amazonian indigenous philosophy and cosmology [2].

The Warao people of Venezuela and Guyana are known to avoid hunting big game species, such as tapirs, because they are considered “people of the forest with blood like humans” [7].

Tapir illustration. Source: www.luciekacrova.cz

Tapirs anthropomorphised, the monster of love – representing the human condition. Source: http://www.luciekacrova.cz

The unconditional human condition

The tapir exemplifies “the nature/culture gestalt” [3], transcending the natural world into the realm of the human condition. Though it is but one organism among thousands that humans anthropomorphize.

Why is this tendency to project human-like traits onto non-humans ubiquitous? Some contend that it arises from the human propensity to infer the mental states of others, a necessary skill for which to understand the intentions of peers [8]. It is a by-product of the process that led to human self-awareness and our need to relate to others experientially.

Ecological and cultural heritage at stake for tapir steak

Tapirs are endangered due to habitat loss and over-hunting. If they become extinct, the rainforests will lose not only a keystone species, but also the animal-human-spiritual relationships associated with them. And it is perhaps these fundamental human conceptions and intangible relationships to nature that primarily underlie motivations to care for our environment.

Besides, a world without tapirs is unsatisfying on so many levels!

About the Author - Charlotte Jennings is a PhD candidate in the Museum of Vertebrate Zoology and Department of Integrative Biology at the University of California, Berkeley. Her evolutionary biogeography research addresses questions related to latitudinal patterns and elevational gradients in biodiversity, though she has tangential interests in conservation, environmental science, anthropology, geography, the intersection of art and science, and education. She lives in Berkeley with her houseplants.  Charlotte is holding a microhylid frog in Papua New Guinea

About the Author – Charlotte Jennings is a PhD candidate in the Museum of Vertebrate Zoology and Department of Integrative Biology at the University of California, Berkeley. Her evolutionary biogeography research addresses questions related to latitudinal patterns and elevational gradients in biodiversity, though she has tangential interests in conservation, environmental science, anthropology, geography, the intersection of art and science, and education. She lives in Berkeley with her houseplants.
Charlotte is holding a microhylid frog in Papua New Guinea

Bibliography

1. Benson, E.P. Birds and Beasts of Ancient Latin America. University Press of Florida, 1997.

2. Bodley, J.H. Cultural Anthropology: Tribes, States, and the Global System, 5th ed. Lanham: AltaMira Press, 2011.

3. Gade, Daniel W. Nature and Culture in the Andes. Madison: The University of Wisconsin Press, 1936.

4. Tedlock, B. “Sharing and Interpreting Dreams in Amerindian Nations”. Dream Cultures: Explorations in the Comparative History of Dreaming. Ed. D. Shulman and G.G. Stroumsa. New York: Oxford University Press, 1999.

5. Reichel-Dolmatoff, G. Shamanism and Art of the Eastern Tukanoan Indians: Colombian Northwest Amazon. Netherlands: E. J. Brill, 1987.

6. Loveland, F.O. “Watch That Pot or the Waksuk Will Eat You Up: An Analysis of Male and Female Roles in Rama Indian Myth.” Sex Roles and Social Change in Native Lower Central American Societies. Ed. C. A. Loveland and F. O. Loveland. The Board of Trustees of the University of Illinois,1982.

7. Balick, J., Elisabetsky, E., and S.A. Laird. Medicinal Resources of the Tropical Forests: Biodiversity and Its Importance to Human Health. New York: Columbia University Press, 1996.

8. Eddy, T.J., Gallup, G.G., and D.J. Povinelli. 1993. Attribution of Cognitive States to Animals: Anthropomorphism in Comparative Perspective. Journal of Social Issues, 49(1): 87-101.

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