by Council of Outdoor Recreation Association NZ researchers (CORANZ)
The Department of Conservation is desperately trying to debunk the scientific view that deer and moa browsing are similar …
DoC challenging the science on moa and similar browsing today
The Department of Conservation is desperately trying to debunk the scientific view that deer and moa browsing are similar by its posted facebook items. The post is headed “Aren’t deer just replacing moa?” Here’s George Ledgard, DOC senior Technical Advisor, in Forest Hill, Southland busting some myths around the idea.
George Ledgard who may or may not have a scientific degree, is being very bold in challenging the views of some very highly regarded, indeed eminent scientists who see a strong similarity between the era when there was moa compared to today where moa are extinct and deer and other wild animals such as tahr and chamois are the browsers of grass and foliage.
George Ledgard’s credentials
CORANZ endeavoured to find George Ledgard’s qualifications. While it lists other DOC spokespersons as being a “scientist” or “biologist”, here is what DoC says about George Ledgard.
“George knows everything there is to know about hooved creatures that walk on their toes – ungulates, for those in the know – and he’s a keen hunter as well as a technical advisor on the topic of wild animals. Hear about where we’re at with hunting and wild animal control, from one of our foremost experts who is also a hunter. George wears all the hats.”
No mention of him being a scientist.
Assuming George Ledgard is not a scientist but a “technical advisor”, here are what some qualified scientists say.
World’s Number One – Dr Graeme Caughley
Top of the experts must be New Zealander the late Dr. Graeme Caughley who has been rated as the world’s number one authority on ungulates. Moa were and deer are herbivores, i.e. eating vegetation by browsing.
At a seminar in 1988, Dr Graeme Caughley presented a paper in which he said there were three regimes of defoliation (i.e. browsing.
“Up to about 1400AD the herbivore component of the plant-herbivore system was dominated by a number of large avian (bird) grazers and browsers. The best known of these, the moa, comprised 11 species varying in weight between about 30 kg and perhaps 350 kg”.
Basically there were three periods of browser/vegetation relationships:-
- Strong browsing pressure over some 60 million years by the various moa species which lived from lowland through forest and scrublands to alpine snow grass tops.
- With the extinction of moa by Polynesian colonists, the browsing of vegetation declined greatly to virtually no browsing except for canopy browsers like kokako and native pigeon.
- Introduction and acclimatisation of deer and other wild animals re-establishes considerable browsing.
Dr. Graeme Caughley termed period two with little browsing as “unnatural”.
Besides Dr Caughley’s very qualified view, others have acknowledged the similarity between moa and deer browsing in the ecology of New Zealand. Eminent biologist and writer A R Wallace in his UK book on “Darwinism” back in 1889 commented that “moa —-for countless ages, took the place of mammals in New Zealand”.
The phrase Countless ages is significant.
Millions of Years
New Zealand’s vegetation was subjected to browsing pressure by firstly vegetarian dinosaurs and then for probably 50 to 60 million years by moa.
Vegetation evolved defence mechanisms to counter the browsing by birds with thorns, divaricating branch structure and even toxins
More recently in 1986 at a symposium on “Moas, Mammals and Climate Change in the Ecological History of New Zealand” various scientists agreed with Dr Caughley’s assessment.
Typical was the comment by I A E Atkinson and R M Greenwood that “it is apparent that the established view that New Zealand’s plants and vegetation evolved in the absence of browsing animals is wrong.”
Little difference
At the same symposium, C J Burrows, B M McCulloch and M Trotter in a paper said “the feeding effects of moa may not have been very different from those of browsing animals.”
Scientist Les Batchelor referred to plants as being “a selective response to browsing by moa.” He estimated the moa population was between six and 12 million birds. Dr Caughley estimated the moa population as at least six million.
In 2002 the Department of Conservation based on Landcare Research estimated the wild deer population at 250,000.
The contrast between six million moa and 300,000 deer is obvious.
Two years later another seminar, Dr Peter Wardle of DSIR said “that these (divaricating) plants are adapted to withstand moa browsing.”
Dr Matt McGlone said habitats “were subjected to considerable browsing pressure by moas.” Two other scientists said ”browsing is not new to the New Zealand flora and landscape. Until about 1000 years ago, indigenous browsers probably exploited the plant cover to its capacity to sustain them, locally exceeding it and locally under-using it.”
They then said “browsing habits of introduced animals (deer) are not too dissimilar from those of lost avi-fauna (moas and others), natural soil and water values might not be compromised were animals left to achieve stable populations.”
Another scientist’s view was that the vegetation was dependent on a “browsing regime” for “its continued existence in that stable form.”
“Bafflegab” propaganda on browsing
Later at the 1988 seminar Dr Graeme Caughley delivered some sharp words on the role of deer and departmental attitudes. He added that staff departments found difficulty in justifying policies that were anti-wild animal.
“They cannot think up a general justification for using it, hence the bafflegab (propaganda) —that presently poses as policy.”
Is DoC with its facebook posts, such as George Ledgard’s, resorting to “bafflegab?
Moa’s chief predator was the giant Haast Eagle until the Maori colonists arrived and intensively hunted the moa.
The late Dr Graeme Caughley rated in his day as the world’s Number One wild animal ecologist.
And while on the subject of DOC, more on a very old awful practice:-
Interesting.