Researchers found the faeces, known as coprolites, at the entrance to the remote Euphrates Cave, which is at the base of a cliff at the eastern end of the Garibaldi Plateau in Kahurangi National Park.
The cave is at the treeline - about 1000 metres - in an environment and region from which the diets of moa have been virtually unknown.
The oldest of the 35 coprolites studied were deposited as long as 7000 years ago, making them the oldest moa coprolites yet discovered.
The most recent is from about 600 to 700 years ago, just before moa became extinct.
Researchers identified at least 67 plant species from the coprolites, including the first evidence that moa fed on the nectar-rich flowers of New Zealand flax and tree fuchsia.
The presence of intact seeds in many of the coprolites suggests moa were an important seed disperser for a range of alpine plant species.
The coprolites provided some evidence for recent changes in plant abundance and distribution since human settlement, the study said.
The research was led by Dr Jamie Wood from Landcare Research and published in journal PLoS ONE.
Fuchsia and wineberry were identified from the coprolites, yet were not recorded recently from the Garibaldi Range.
Both plants were highly palatable to introduced herbivores and could suffer severe local declines due to over-browsing.
Further evidence that the pressure from introduced mammals was greater than that in prehuman times, came from the fact that a third of the plants in the coprolites were now largely restricted to trench and sinkhole walls on Garibaldi Plateau.
"Rather than reflecting a tendency for upland moa to feed around these holes, it is more likely that these sites are now refuges to a range of palatable plants, which once may have been more widespread in subalpine herbfields but are now heavily browsed by introduced mammalian herbivores," the study said.
The research did raise the possibility that moa themselves may have caused reduced densities of some plant types.
Several of the plants identified in the moa coprolites also showed structures generally considered to be defensive, including wiry stems, which it is thought could have co-evolved against browsing.
No evidence from the plant remains in the coprolites indicated major vegetation change in the area of Garibaldi Plateau during the 6500 year time span covered by the research.
Beech pollen was common in the coprolites, suggesting beech was the dominant forest type around Euphrates Cave by 7300 years ago, the study said.
Replacement of podocarp forests by a spread of beech is a common pattern of vegetation change found in sedimentary records across the South Island during the Holocene period, which started about 12,000 years ago.
The coprolite study said a soil pollen core from the Garibaldi Range would provide useful information on local vegetation change during the Holocene, particularly for measuring changes in treeline boundaries.
That could show whether grasslands may have been more accessible to moa from the Euphrates Cave entrance than was now the case.
Due to its elevation, the Garibaldi Plateau received a large amount of snowfall during winter, and the dominance of pollen from late spring-summer flowering plants in the coprolites suggested feeding during those seasons.
It was likely that upland moa moved from the subalpine zone into lower elevation forests during winter.
Overall, the floral composition of the Euphrates Cave coprolites supported previous interpretations that upland moa were highly generalist feeders, browsing trees and shrubs, and grazing low herbs, in a broad range of habitats including forest, shrubland and grassland, the study said.
The relatively recent extinction of moa meant the ecological impact of their loss was yet to be fully realised.
Some long-lived trees that may have had their juvenile branches browsed upon by moa, or grown from seeds dispersed in moa dung, may still be present in forests.
Across the globe, the functioning of ecosystems had been fundamentally altered by the widespread extinction of many large herbivores during the past 125,000 years.
Replacement of podocarp forests by a spread of beech is a common pattern of vegetation change found in sedimentary records across the South Island during the Holocene period, which started about 12,000 years ago.
The coprolite study said a soil pollen core from the Garibaldi Range would provide useful information on local vegetation change during the Holocene, particularly for measuring changes in treeline boundaries.
That could show whether grasslands may have been more accessible to moa from the Euphrates Cave entrance than was now the case.
Due to its elevation, the Garibaldi Plateau received a large amount of snowfall during winter, and the dominance of pollen from late spring-summer flowering plants in the coprolites suggested feeding during those seasons.
It was likely that upland moa moved from the subalpine zone into lower elevation forests during winter.
Overall, the floral composition of the Euphrates Cave coprolites supported previous interpretations that upland moa were highly generalist feeders, browsing trees and shrubs, and grazing low herbs, in a broad range of habitats including forest, shrubland and grassland, the study said.
The relatively recent extinction of moa meant the ecological impact of their loss was yet to be fully realised.
Some long-lived trees that may have had their juvenile branches browsed upon by moa, or grown from seeds dispersed in moa dung, may still be present in forests.
Across the globe, the functioning of ecosystems had been fundamentally altered by the widespread extinction of many large herbivores during the past 125,000 years.
Source: Stuff
Journal Reference:
Wood JR, Wilmshurst JM, Wagstaff SJ, Worthy TH, Rawlence NJ, et al. (2012) High-Resolution Coproecology: Using Coprolites to Reconstruct the Habits and Habitats of New Zealand’s Extinct Upland Moa (Megalapteryx didinus). PLoS ONE 7(6): e40025. doi:10.1371/journal.pone.0040025