After 70 days, 14 helicopter flights and a large amount of stamina in the bizarrely hot, Southland summer, the majority of the wild takahē territories have been searched. This has completed the 2017 Murchison Mountain takahē survey. We checked in with Julie Harvey to look at what the Takahē Recovery Team found. This is the third blog in the takahē survey series. Check out the first and second blogs for more information.
How are takahē monitored?
Since 2011, the Takahē Recovery Programme has moved to a different method of monitoring the birds, utilising regular remote monitoring, known as Skyranger monitoring. This is where a large proportion of birds wear transmitters and are tracked via a receiver in an aircraft. The method provides a regular snapshot of not only individual bird’s locations but also population status. Regular remote monitoring also allows the team to respond more quickly with the most appropriate type of management.
How often is the traditional survey completed?
Traditional foot surveys, like the one we have just completed, are now only done once every 3-5 years, and are primarily a method of ground truthing the population estimate gained from the remote monitoring (Skyranger) survivorship study.
These population surveys are also compared over time. Repeating the surveys of the same known territories allows the team to monitor the health of the population and therefore how well the pest and bird management applied to the Murchison Mountains is going.
What did the team observe in this year’s survey?
The happiness of the takahē rangers who have completed numerous Murchison Mountain surveys has been evident when they return from trips to territories (previously empty from the devastating stoat plague in 2007) which are again home to takahē pairs and the sound of their calls.
The team observed a large amount of breeding signs, with most pairs in the early stages of setting up a nest, but also 10 nests with eggs and one pair with a young chick in tow! Although not all young will be expected to reach adulthood; the observations suggest that recruitment of young birds to the population will be comparable with previous years.
While surveying, the team worked to minimise disturbance due to the risk posed to breeding birds. However, they did manage to catch two wild pre-breeding sub-adults to fit with leg bands and transmitters. It is necessary to catch birds where possible to maintain a good sample for the remote monitoring study.
One unbanded bird caught in Takahē Valley, the site of the birds’ rediscovery, has been named Telfer, the maiden name of Joan Watson who was in Dr Geoffrey Orbell’s party. Another sub-adult was caught and has been named Luminosa – the latin name of the New Zealand glow-worms that live in the cave below the Murchison Mountains. Quite fitting given the iridescent colours of the takahē in the sun. The team also managed to catch Korokoro and fit a new transmitter to her (she had previously dropped hers) and Tintooki was sighted for the first time since 2007!
What are the results from this year’s survey?
A minimum number of 118 takahē are known to be roaming their wild refuge. Due to the ruggedness of the terrain, the sheer area to cover and the secrecy of the birds, the team cannot head count every individual takahē. The population survey cannot be referred to as a census as not every individual is accounted for.
The total count is up from the last survey conducted in 2014 where 79 birds were recorded. Although the population has been boosted with the release of over 50 birds since 2015, the team are pleased with the results. The tally of birds seen gives a minimum number and the dry conditions meant many birds wearing transmitters were found outside of their core territories i.e. in the valley floors where water is more readily available. Many of the birds recently released were found paired with ‘local’ birds and often nesting, confirming the pre-release ‘training’ they receive at the Burwood Takahē Centre, is suitable.
The survivorship analysis based on the monitoring data estimates a current population of 130 wild takahē, which is likely to be much closer to the actual population. Overall, the Takahē Recovery Programme is happy with the results of the survey, proving the population estimate derived from the remote monitoring is accurate. Seeing the population expand into previously empty territories, and the successful integration of many of the recently released birds, gives the team confidence that a large and healthy takahē population can be sustained into the future.