Protect our Eungella Honeyeater

Climate and selective logging impacts on the Eungella Honeyeater (Bolemoreus hindwoodi), Mackay’s only endemic bird species

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Mackay Conservation Group has partnered with Birdlife Australia, Birdlife Mackay and other volunteers for the past three winters, 2014-2016, to monitor the impacts of logging on the endemic Eungella Honeyeater and other honeyeaters in the state forests surrounding Eungella National Park west of Mackay in the Clarke Range.

For bird species with a population of 10,000 or less if the population shows a decline in three consecutive years of monitoring, it can be nominated under the Australian Environmental Protection and Biodiversity Conservation Act 1999 as a threatened species. That designation could give it increased protection from any threatening processes.

The Department of Agriculture, Fishing and Forestry (DAFF) approved the resumption of logging in the Cathu and Crediton State Forests in 2013 more than a decade after logging ceased. The Eungella Honeyeater is only found in the rainforest of Eungella National Park (http://www.nprsr.qld.gov.au/parks/eungella/) and surrounding state forest woodlands.

Along with other honeyeater species there, they play an important ecological role in keeping these forests healthy by eating lerps, (larvae of the psyllid insect with a high carbohydrate covering). They are also a pollinator of native tree and vine species as they take nectar from their flowers.

Birdlife Australia (http://www.birdlife.org.au/) helped us initially design and locate three 10 hectare monitoring sites in Crediton State Forest (http://www.nprsr.qld.gov.au/parks/crediton/) so we could gather data to see if logging was having an impact and if the population of this species is in decline. Monitoring also began in Cathu State Forest (http://www.nprsr.qld.gov.au/parks/cathu/) in 2015-2016. Birdlife Mackay volunteers conducted weekly surveys during winter months in Crediton State Forest in 2014 and 2015 and bi-weekly after that. Coordination of the surveys was by Darryl Barnes, President of Birdlife Mackay (http://www.birdlife.org.au/locations/birdlife-mackay). Analysis of data was undertaken by Mackay Conservation Group.

Earlier data from surveys conducted since 1998 recorded a dramatic drop from 60 to a current maximum of 10 birds per survey in 2007.  We found the most likely cause was a significant drop in the flowering density of the woodland trees. This was possibly due to a decrease in larger rainfall events since 1991.

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Our data through 2015 indicated that the Eungella Honeyeater population has not dropped much below the 2,500-population for the Area of Occupancy (estimated by Queensland Parks Wildlife Service ranger Derec Ball in 2007). That made it appear that the population of Eungella Honeyeaters was in dramatic decline.

Two of our 2014-2016 monitoring plots were close to the current logging operations. Eungella Honeyeater numbers were much lower, ranging from zero to just a few per site near the logging sites, and significantly higher at the third monitoring plot which was well removed from the logging.

The two sites near the logging were also lower in tree density than in site three so that may have been the cause of lower Eungella Honeyeater numbers there.  In 2016 we selected (with the assistance of DAFF) another site near the logged sites that was similar in tree density to the logged sites.  Results showed that there were more Eungella Honeyeaters in the unlogged lower tree density sites than in the logged sites, although numbers were still lower than in the higher tree density monitoring site.  This added to the evidence that selective logging was having an impact.

There was a strong linear correlation between numbers of Eungella Honeyeaters (EH) recorded through 2015 and tree density with none recorded once tree density falls below 10 per hectare.

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It appears that lerp populations can sustain the Eungella Honeyeater where tree density is above 10 trees per hectare, and the Eungella Honeyeater can be a significant pollinator of trees and vines when rainfall is high enough to sustain higher flowering densities.  Logging does have some adverse impact on the Eungella Honeyeater and other honeyeaters because it reduces tree density.

The 2016 data should be analysed by early 2017, and is expected to support the current conclusions. A more in depth analysis of the population estimates within the Area of Occupancy of the Eungella Honeyeater also needs to be done to see if current population estimates remain close to 2,500 i.e. has there been a significant drop in the population of this species?

Continuing research is now needed to understand and quantify the economic as well as the environmental benefits of protecting the habitat of the Eungella Honeyeater because it attracts many bird-watching eco-tourists each year and is unique to our region. This species is also classified as at medium risk from climate change as it is only found at higher elevations and if temperatures continue to climb it eventually will run out of room to go higher.

This research was partially supported by grants from the Norman Wettenhall Foundation in 2014, and by Mackay Regional Council in 2015 and 2016.  More detailed information about our research activities can be obtained by contacting Patricia Julien on patricia@mackayconservationgroup.org.au.

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