The coat colour variation described by Harvey Morrow  in feral horses of central North Island during and around the 1920s is not evident in today’s Kaimanawa horses. The colour illustrations of Kaimanawa horses in his early 1970s book also look to have todays more limited palate.
But Morrow’s photographs of the remnant but now extinct Roto Aira population around National Park just 35 kilometers from where the Kaimanawa population roams today shows a Tabiano pony behind two chestnuts and a bay (see photograph below). Have alleles for pattern and hue been lost or were they never present in the Kaimanawa herd?
Any of the few more colourful horses might have been taken from the population, being more attractive to the musterer’s eye. Harvey Morrow indicates as much – horses with unique coats were favoured for capture.
The steel-grey mare was still on her own when we made our usual survey from Wild Horse Lookout next morning. […] Her capture was only a matter of minutes. Chapter 7 – The Steel-grey Mare.
Not long after the return of the grey mare to the run a new mare appeared. […] She was roan in colour and in due course produced a lovely roan colt. […] Her colt developed into a very attractive animal. … we did covet the colt. Chapter 8 – The Roan Colt.
The large musters from the Kaimanawa population during the 1950s and 60s for pet food too might have culled colour from the population. It is more likely, however, that alleles for hue and pattern were never bred into Kaimanawa horses.
The domestic origins of the Kaimanawa population are not as diverse as those that no longer exist in other parts of New Zealand. The Kaimanawa population are most recently descended from the release of cattle and sheep station (farm) and cavalry (military) horses that were less likely to be bred for brighter, patterned colours. Genetic studies confirm that Kaimanawa horses are most similar to thoroughbreds and thoroughbred crosses that made up most of the military and hill-country farm horses of the early 20th century .
Some surmise the genetic influence also of the Carlyon and Comet ponies in the Kaimanwa population today – ponies bred during the late-19th century for the demanding conditions of colonial New Zealand. And, the Carlyon and Comet were not colourful breeds either, being descended from imported Exmoor and Welsh stock renowned for their plain ‘browness’.
Such ‘brown’ horses are certainly not a genetic type but chestnuts or, less often, bays whose coat colour is much darker than is typical but it is not possible, without genetic testing, to know which. Indeed, indecipherable brown coat colours amongst the Kaimanawa horses, where they made up almost 10% of our studied population, might be attributed to this early English and Welsh genetic stock.
The Kaimanawa horse, is seems, is classically plain – its genome being largely dominated by black and chestnut alleles and bereft of alleles for hue and pattern.
Colours amongst the brown
And so it seems Harvey Morrow’s colourful wild horses and their descendants didn’t make it to the Kaimanawa Mountains or, if a few did, they didn’t elude capture or muster. Instead, the stoic, pragmatic choice for browness by first-colonists and then by cavalry and hard-country farmers, colours the Kaimanawa horse of today.
Nevertheless, over the four years that would follow seeing my first Kaimanawa horse, we would adapt descriptions of coat colour as part of our horse identikit and make the most of what variation there was. We developed detailed, sometimes unorthodox, descriptions of a horse’s pelage, especially amongst new foals to the study and unbranded horses. Sometimes descriptions of variations in the darkness of ‘brown’ across a horse’s body proved valuable. We recorded lighter, darker, chocolate and black browns. Some had lighter brown muzzles, breasts and barrels.
Looking closer now and for longer at my first band on that cool, clear August day in 1994, I began to differentiate amongst Kaimanawa colours. The mare was lighter than her foal – what I might describe now as a yellow chestnut with flaxen (bleached) mane and tail. Another mare was bay and the stallion was so dark as to probably be black. More brown than most they may be, but I would learn to see individuals and discover the colourful lives of Kaimanawa horses.