Friday 30 January 2015

Autotomy: The 'Tail' of a Great Escape

Self-mutilation, self-amputation, separation of a body part: it all comes down to one thing – autotomy can be ‘Life over Limb’!

As a little girl, I remember watching in horror as a lizard I was trying to protect from my pet cat suddenly ran off without its tail, leaving my cat and I staring in bewilderment at a wriggling lizard tail. I now know that this was a great example of ‘autotomy’.
 

Image source: buzz-master.com
Autotomy is a self-defence mechanism that many animal species can utilise. For example, if a predator seizes the tail of a striped skink, the skink can detach its tail from the rest of its body, sacrificing the tail, but escaping with its life.

If the predator does not consume the tail, the skink may return to the 'scene of the crime' once the predator has left and eat its own discarded tail.

As the skink’s tail is an important site for the storage of nutrients, the skink can ‘win back’ some of the nutrients lost in the fight (glad I’m not a skink).

Further, in the case of the striped skink, the animal can regenerate the sacrificed tail.

So the question remains - despite its immediate advantage in terms of survival, does autotomy have a downside?


The answer is most likely 'yes'.

http://blog.thereptilezoo.com/post/Auto-Whaty!.aspx
The animal could have impaired locomotion and reduced ability for foraging in the event a limb is lost...and even limited reproductive options if the detached body part is important for mate attraction.

Is autotomy really the 'great escape' or merely a short-term survival mechanism? We'd like to ask what you think...

 
The ANT Blog
(Written by Jenny Bell)

Friday 16 January 2015

New year, new beginnings...

Happy New Year everyone!

All of us at ANT hope that you had ample opportunity to rejuvenate during the festive period. Just before we closed for the year in 2014, we received an e-mail from the Chairman of the Black Eagle Project Roodekrans (who attended our Savanna Bird Course), which we thought you might find interesting, even though it's not exactly 'hot off the press' now.

Hi All,
It has been some time since I last updated you on what is happening.
Our juvenile “Jono” is still in the natal area although the aggression towards him has started to escalate, and it won’t be too long now before he will have to leave and fend for himself. The latest newsletter below will explain this a little more.
The project itself received a huge financial boost on Monday this week when Silverstar Casino handed over a cheque for R 157,433.50 to us at a special function. Their support for our work has been absolutely amazing and we are indeed privileged to have them as our main sponsor. Watch our Facebook page for a full report, and we also hope to see the Press coverage in the next few days.
Remember our website address is
www.blackeagles.co.za
Regards
Gerald Draper


Jono, an immature Verreauxs' Eagle, surveying the gardens before he was forced to leave forever
A note about the naming of the offspring by the 'Black Eagle Project Roodekrans':
Jon Oliver, CEO of Africam.com sadly passed away just a few days before Emoyeni's chick was born in June 2014, therefore, we think it only fitting that this eaglet should be named 'Jono', which is what he was always called by his friends and family.


The juvenile Verreauxs' (Black) Eagle had only been off the nest for six and a half weeks when the first unsuspected parental blows of aggressive behaviour struck him during the weekend of 25/26 October!
12 November 2014:
This behaviour is deemed far too soon by any standards for this species and should only have commenced during the tenth week, post fledging. Having thus requested that the 'Black Eagle Project Roodekrans' members specifically monitor this behaviour, the juvenile had been fortunate in that there did not appear to be too much conflict during the following week and weekend, thus being quite relaxed.
 
It's not fun having your parents turn on you so aggressively...
The calm before the storm was short-lived in that a major onslaught rained upon him from all directions on Saturday 8th November, with the female contributing for the first time too! One can only imagine how the juvenile must have felt…here he is biding his own…his parents bring him prey…he still roosts on the nest…then without any warning whatsoever the adult pair launch a very aggressive and prolonged attack upon him, and as the proverbial saying goes “you have to be cruel to be kind” rings true in this regard under these circumstances! Some of the most hardened avian photographers that have been recording the onslaught mentioned that at times it was too difficult to observe as the juvenile called incessantly in his attempt to escape the blows, be it in flight or perched…his world is coming down on him…fast and furious! Interestingly however, that Sunday, 9th November, was a quiet day with no aggression noted…as if nothing happened, which will confuse the juvenile even more in the days to come.
 
Jono will have no choice but to leave his parents' territory
Ultimately, in an effort to escape the relentless harassment, the juvenile will gradually be pushed out of its natal home range (territory) by the adults, which is a gradual process that can last two or three weeks and, during this period, he is unable to return to the nesting gorge that was his home since hatching five months ago. One can really feel for him, he will soon be unable to sleep on the nest that was his comfort zone and will be obliged to roost in a tree just like his parents have been doing…something he is not used to...yet.

As mentioned in October, it is imperative that the juvenile achieves 100% in all his subjects as, without these qualifications, his chances of survival lessens should he be unable to grasp the importance of tuition during the post fledging stages. Sleeping on the nest during the first month after fledging is acceptable, but not during the second month and beyond...mainly because when he is shoved out of the home range area, there will be no nest anywhere that awaits him and suddenly his own instinct will have to be engaged to ensure that he must roost out of harm’s way…most preferably on a sheer inaccessible rock face or a tall secure tree.

More so, he has never been taught to hunt, he has never accompanied his parents on a hunting sortie and, for as long as he has been at the nesting gorge, prey has always been delivered to him and all he had to do was consume. Whilst he is yet within the home range, they will continue to feed him, but not too frequently and possibly only half a meal every two or three days maybe more. Quite inadequate for a growing juvenile and instinct will once again drive himself to hunt his own prey and this may be difficult as he will never be certain of a successful hunt. During the first few attempts, he may only get lucky once in every tenth try, which is particularly nerve wracking! On the positive side though, whilst growing up from chick to eaglet to juvenile stages, he had imprinted all the prey types that were brought to him and this should give him a head start to survive as he will recognise the items within a split second of seeing them and specifically hunt that prey type. It is finding these that will put him to the test once more...

Written by Bo van der Lecq,  Black Eagle Project Roodekrans
Photos by Ernest Porter
12 November 2014 - reproduced here with permission (and grateful thanks from ANT!)
 
Jono was last seen at Walter Sisulu National Botanical Gardens (Johannesburg) on 12th December 2014...and we wish him a successful future - hambe kahle Jono!
 
The ANT Blog