Monday, December 23, 2013

Who uses tree cavities and nest boxes in PNG?


Who uses tree cavities and nest boxes in PNG?
(continued)

Part of the study surveyed publications to tally which species are known to occupy cavities for den or nest sites.  As might be expected, there are quite a few species in New Guinea where we have no records of where they nest or den.  But from the records we could find, at least 50 species of mammals and 118 species of birds use tree cavities.  That makes this a pretty important resource! 

We also were able to count how many trees have cavities in a hectare of lowland rainforest thanks to a project by the Binatang Research Centre in Madang that included felling the trees in a hectare of primary and a hectare of secondary forest.  The secondary forest had no cavities and a hectare of primary forest had 26 cavities, mostly in large trees-- the same ones that would be harvested by loggers.  In other words, those 168 species of birds and mammals are somewhat to very reliant on there being large trees in primary forest.  Availability could decrease as more and more forest is logged in the New Guinea region.



So did the nest boxes attract many occupants?  After less than a year, things were moving into the boxes.  Sugar gliders and Northern common cuscus moved in some boxes at Wasu, especially the largest ones.  A good assortment of snakes and geckos also moved in.  Honeybees occupied quite a few boxes and probably kept out mammals and birds.  The team had to be careful when climbing up to inspect a box to make sure they weren't going to be stung when so vulnerable high in a tree. Unfortunately we were not able to follow up with long term monitoring at Wasu for a variety of reasons (Searching for pekpek lays it all out).  We think it takes many months for animals to find the boxes.


Sugar glider at the bottom of a box, it has built a nice den of leaves in the box.

Sugar gliders would burrow into the wood shavings we put in the boxes.

At Gahavasuka Daniel Solomon Okena monitored 30 boxes for about two years and found Silky cuscus (8) took to them quite readily, along with more Sugar gliders.  We did not have birds moving into the boxes to nest.  We did find feathers in some boxes, suggesting maybe they roosted in the boxes at night.  But the monitoring period was relatively short and quite possibly with a bit more time birds will find them in future breeding seasons. 

A few Sugar gliders in a box with fresh leaves added to their den.

A gecko inside one of the nest boxes


What started with some incidental observations at Crater Mountain, led to a nice project by the gang at the PNG Institute of Biological Research and a publication in Tropical Conservation Science.




you can get the full publication here under the Academic Research tab
 or at:
http://tropicalconservationscience.mongabay.com/content/v6/index-dec-13.html

Thursday, December 19, 2013

Wildlife in tree cavities and nest boxes in Papua New Guinea

A view to the coast from the Wasu study area




You never know where some incidental observations will lead.

One of the best aspects of my research studying cassowary dung was that I was free to observe and explore the forest around me.  If you observe or monitor animals in any way, you often have to focus on your beast to the exclusion of cool things happening around you.  Not so with cassowary pekpek.  It stays put and can be ignored while watching something else.  The data are just as good if you stop to watch a hornbill.

While doing my fieldwork I made several observations of parrots and other birds fighting over ownership of tree cavities where they presumably nested.  Sometimes I'd note the occupant as one species only to return later and find some usurper had taken over the site.  I suspected tree cavities were in strong demand.  There are no woodpeckers in New Guinea, so everyone that nests or dens in tree hollows pretty much has to find one.  No one is excavating new holes.

As a preliminary experiment I made and put up an artificial nest box within view of the station verandah.  Soon it was evident that some animal had chewed the opening to make it larger and some twigs were protruding through the hole.  Possibly one of the many rat species endemic to New Guinea had made a nest.  In a few months a bat displaced the presumed rat.  We could often see the claw on the "finger" at the bend of the wing protruding through the hole and hanging on to the outside of the box.  I stored away this information.

Some of the team horsing around in the study area.  Paul Igag seated.

Years later a PNG student, Diatpain Warakai, was looking for a field project and we thought about nest boxes.  Deb Wright worked her magic raising funds and obtained support to build and deploy a bunch of nest boxes. 

The study was a large collaboration.  A carpenter was hired to build the boxes.  Our friends now at the PNG Institute of Biological Research, Muse Opiang and Daniel Solomon Okena, helped Diat with the fieldwork.  Paul Igag acted as uncle and trained the others in tree climbing (sadly Paul passed away before the publication of the results).  Half a dozen local men helped put the boxes up.  The team put out nest boxes and monitored them to learn what occupied them.  Would cuscus move in?  Would parrots nest in them? Would we be able to use nest boxes as a way to study the elusive arboreal mammals of New Guinea?  Putting out nearly 200 boxes in 2006 was the culmination of those first incidental observations fifteen years earlier while roaming the Crater Mountain forests searching for pekpek.

One of the boxes in place and waiting for an occupant
[more to follow on the results]


Carrying the pre-made boxes to the study site employed a lot of workers.