Don the technophile

Don is one year old!  It has been an exciting journey following this particular eagle, made possible from the start by constructing a makeshift nesting platform.  Granted it wasn't photographically aesthetic, but the eagles liked it.  And Victoria and Albert soon had a nest they were happy to use. The little crowned eagle chick(s) hatched on the 8 October 2012.  Twenty days later the monitoring camera was installed, and from that point the nest activities were observed in intimate detail. 

100,000 images later Dons development, and all the food he’d consumed in 5 months, had been recorded.  He fledged from the nest on 19 Jan, and has been tended to by his parents all this time.  We are not sure if he’s managed to hunt successfully yet, but his dependency is now lapsing its first year.  Recently some aggressive confrontations between the queen of this realm Victoria, and son Don have suggested he’ll soon no longer be welcome at home.  Sometime between 7 and 13 months old the young crowned eagles will be ousted from their parents’ territory.  Its time to travel the world, become self-employed and eventually invest in the housing market.  Don may have a tough time establishing a new territory; a raptors survival is most tenuous in its first few years, and he'll have to face many challenges.  It will be about four years before he’s man enough to breed himself. 

How far and for how long crowned eagles roam is still not clear and so, with the support and financial support of the Victoria Country Clue Estate management and residents, and the technology, knowledge, and advice from Ben at Raptor Rescue, we have been able to fit an Avi-Track solar-GPS telemetry unit to Don. Weighing 70 grams, it is 2.2% of his weight, while bulky, the box dimensions have to be tall to capture enough sun over his back feathers.  While these units have been used effectively on vultures, and many other large raptors, crowned eagles spent much of their time in the shadows of the forest so the solar powered units are going to be tested to their limits.  

The dispersal data that we record from Dons movements will be aiming to answer many still unanswered questions about the crowned eagles sub-adult years.  And most importantly we will be able to respond quickly to any suspected inactivity indicating injury or death.  Five juveniles born in 2011 were killed by various causes including a pellet gun, and three electrocutions.

Ferncliffe, where Don was captured on 26 September.  Photo Burkhard Schlosser 2013

Don showing interest in the trap.  Photo Burkhard Schlosser 2013

Ron Perks and Ben Hoffman assisting with the project.  Photo Burkhard Schlosser 2013

Threading the Avi-track GPS unit.  Photo Burkhard Schlosser 2013

The makeshift field lab.  Photo Burkhard Schlosser 2013

fitting the solar powered GPS - GSM device. Photo Burkhard Schlosser 2013

Fitting the harness.  Photo Burkhard Schlosser 2013

biometrics: inner talon 52.4mm. Photo Burkhard Schlosser 2013

keep clear of the pointy end. Photo Burkhard Schlosser 2013

Preparing to weigh Don, at 2,700g he is fit and healthy.  Photo Burkhard Schlosser 2013

Taking the hood off a few seconds prior to release.  Photo Burkhard Schlosser 2013

Lift-off.  Photo Burkhard Schlosser 2013

Up up and away.  Photo Burkhard Schlosser 2013

and cruising back to his perch for the evening.  Photo Burkhard Schlosser 2013

Its been time-consuming this week.  With GPS positions appearing on a private webserver exactly on schedule three times a day, I chased a few morning and noon fixes.  Its already dark by the evening fix, when Don should be settled in to roost, and finding him then is difficult.  Finding him anytime is difficult, but I did manage to hear him twice from the vicinity of the GPS location.

We watch in anticipation for Dons next move, maybe he'll leave soon, or he might even stay until this time NEXT year, when the Victoria and Albert will hopefully breed again and kick him out for good.  So it time to wish Don well for this next stage of his life.

A bat in the hand

One of the first discoveries having arrived at UKZN in Pietermaritzburg in April last year,was the roost of the Epauletted Fruit bats right here on campus.  Its such a novelty for a Kiwi, to have big bats so close to home and work.  Infact Prof Downs was recollecting a story about a lady that worked in her office right against the roost tree.  She had to work with her curtains closed because she was uneasy with the bats constantly staring at her with those big beady eyes all day.  Personally I would move into that office right now given half a chance!

An MSc research project was completed in 2012. "Seasonal home range and foraging movements of the Wahlbergs Epauletted Fruit Bat in an urban environment." By D P Rollinson.  The bats were fitted with transmitters and followed on foraging expeditions.  The research was wrapping up when I arrived in April, and while bats were being recaptured to remove the transmitters used in the study,  sadly I never managed to get involved at that time.

Fortunately new research is beginning on the bats that use this roost. Providing an opportunity to get in amongst it. Dr. Lorinda Jordaan is hoping to catch a few bats every month. The longitudinal study will focus is on the bats breeding cycle, and in particular on the aromatic compounds secreted special glands on their shoulders that give them their namessake - epaulettes.

This last weekend was particularly successful, we caught four on the first night and six on the second. Getting an opportunity to get up close, extract them from nest and handle them in the lab, it was a real buzz. Swabs of the epaulettes were taken and then the bats were weighed and released.

Fruit bat roost tree

The flyway interceptor

Prof. Colleen Downs extracting a bat from the net

Released after sampling

Wireless Wildlife GPS 1

Early in December I also received the batch of GPS data loggers that will be fitted to resident adult eagles, and be used to inform habitat use and home range.  One such bird was captured and the GPS unit has been operating very well.

To have the first adult eagle in the hand was a magical experience.  There was a feeling mixed between absolute awe at the size and beauty of this female, and coherent awareness of need to get our job done with the minimum stress to her.  The unit was fitted surprisingly quickly, having settled on a pelvic mount design rather than the traditional backpack harness that is typical for raptor telemetry.  This is an emerging technique that has proven very successful on the Drakensberg Bearded Vulture research.  The design was decided on after much deliberation between eagle fundi's and incorporates factors such as speed of fitting, less risk of entanglement during aggressive attacks in forest cover, and the snug fit that doesnt require fine tuned allowances for changes in shape that unit fitted by a chest harness requires (allowances for breathing and flapping, and changes in muscle mass and fat deposits).  These units will also more safely fall away when the teflon wears through and the unit falls off.

Despite many 4am starts, and many attempts at various birds around the study site, other eagles have thus far eluded me.  My techniques were devised for use when there young nestlings.  They are now about a month older than I'd hoped, and as the young eagles fledge in the coming month or two, the adults will be more and more difficult to find.