A new study has revealed some striking and perhaps ominous similarities between New Zealand's endangered flightless birds and those that have already been lost to extinction.
Using computer simulations, scientists from the University of Adelaide have been able to reconstruct with some confidence the geographic range of extinct moa birds, and in particular their last refuges of habitat.
These so-called ‘moa graveyards’ are also where the islands’ remaining flightless birds, including the iconic kiwi, can be found today, as revealed in a new paper published by Nature Ecology and Evolution.
What happened to New Zealand's moa?
New Zealand was once home to many more unique animals than it is today, and amongst these were moa.
These large wingless birds stood as much as 12 ft in height and were once found across New Zealand in diverse habitats, from forests to coastal dunes.
The advent of human colonisation of the islands in the mid-13th century proved disastrous for moa however, with the fossil record revealing that most of them were driven to extinction within two centuries of the first human contact. This was due to a combination of habitat change, introduced species and hunting. Later arrival of Europeans only exacerbated these problems.
The flightless birds that survived these waves of human colonisation face similar threats to this day, with many of them classed as endangered or critically endangered.
Mountain refuges
This new research mapped out the last habitats of six species of moa from across New Zealand, using a combination of fossil evidence and fine-grained computer simulations, finding that the final populations of these birds lived in the high and cold mountainous areas of the islands. These were far from optimal habitats, but they were the areas least impacted by people.
Interestingly it is in these same sub-optimal mountainous regions that threatened but still-living flightless bird species have been found, prior to modern large scale conservation reintroductions.
This similarity between the extinct and extant is especially true of the most threatened of species, such as the kākāpō and takahē.
Repeat patterns: living birds follow extinct moa
Evidence suggests that moa are likely to have disappeared first from the higher-quality lowland habitats, with their rates of population decline decreasing with increased elevation and distance from the shore.
A very similar pattern seems to also have been true for the species that have persisted, with their once expansive ranges now restricted to the same small and suboptimal areas.
Even the most widespread of New Zealand’s eight remaining endemic flightless bird species, the weka and the North Island brown kiwi, have been most frequently sighted close to these final moa sanctuaries.
What does this mean for living flightless birds?
These findings are not necessarily a cause for despair for the fate of New Zealand’s flightless birds, however.
Intensive conservation efforts have been responsible for bringing some of the islands’ most iconic species, including the kākāpō, back from the very brink of extinction, and things are looking much more promising for New Zealand’s birds than they once were.
A deeper understanding of historical extinctions, as has been provided by this research, can only aid and inform such conservation efforts, by giving insights into the dynamics of and the forces behind such extinctions.
Knowing more about the behaviour of the flightless birds that have been lost may well give modern scientists better tools for helping those that remain.
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