๐Ÿพ Maybe the reason I love animals so much, is because the only time they have broken my heart is when theirs has stopped beating.

Saturday, 23 May 2009

Black Eagles

"When we open ourselves to the natural world, we escape the fast-paced bustle of our daily lives. That experience, not only reduces our stress, it also grounds us, reaffirming our connection to the Earth and all its creatures."


"Black Eagle" water colour - Maree©

I am utterly fascinated by birds, raptors in particular. To me they are the kings of the skies and their survival plight, as cities grow and multiply, is of on-going concern to everyone, or should be, at least.

The resident pair of Black Eagles in the Walter Sisulu Botanical Gardens in Roodepoort, Gauteng, South Africa, is under threat from urban spread.



Earlier nesting reports on the Black Eagle pair reads as follows :

Mating
Mating was first observed in March becoming frequent in April 2003. The day prior to laying the eagles were seen to mate five times. The mating observations were consistent with prior years.


Nest of the Black Eagles at Walter Sisulu botanical Gardens, Roodepoort. The nest is monitored by the Black Eagle Cam.



Nest building and laying
Nest building was first observed in February 2004, but increased significantly in March 2004 were on occasions that the black eagles would bring in excess of 10 branches on a daily basis. As Garget (1990) has noted in the Matopos study that after an unsuccessful breeding year there is a tendency for black eagles to move nesting site and use an alternate nest site. However, the Roodekrans black eagles spend most of there efforts building the bottom nest only. It was apparent that they were not going to change nest site. Building continued up to the day of egg laying. It was interesting to note that the male was seen to initiate building on a number of occasions.

Incubation and hatching
Incubation commenced with the laying of the first egg. The majority of the incubation being undertaken by the female, however the male would often relieve the female for periods. The first egg hatched on 2 June 2003, 45 days after laying which is normal. The second egg hatched on 6 June 2003, four days later.

Cain and Abel
The Cain and Abel struggle lasted for 3 days, young Abel died on 9 June 2003. This year the aggression from Cain was minimal and the project thought there might be a chance that Abel would survive. After two days Cain suddenly attacked Abel and did not let up for 24 hours, intervening the prey that was offered to them by the female eagle. On the morning of the 9 June 2003 Abel was dead when the female left the nest at 8.15am.



Fledging
We knew the Roodekrans black eagles were going to surprise us as they do every year. The juvenile eagle only fledged on the 22 September 2003. At 112 days this is the longest recorded fledging for the Black Eagle Project. The longest prior fledging recorded was 106 and 104 days in 1998 and 1993 respectively.

Newton (1979) highlighted that the male eagle chicks in most raptors tend to develop more quickly than females and are therefore more likely to fledge earlier. Observing the chick flying it was obvious from it size that it was a female which corresponds to the lengthy fledging period. It is generally believed that the male juvenile black eagles fledge from about 95 days, in 1993 the chick fledged at 93 days.

Gargett (1990) also notes that observations do not support statements that the young are deliberately starved by the parents in order to encourage them to fly nor that the parents bait the young off the nest with prey. This has not been observed in the Roodekrans black eagles either.
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However, after the juvenile eventually fledged, it was soon apparent that this was a very confident juvenile. This juvenile was very confident in its behaviour when compared to prior juveniles. Prior juveniles tended to hide away in the ravine on the eastern ridge. This juvenile black eagle spend most of it time on Butchers Block while prior chicks have hid in the ravine and were difficult to locate. Soon after fledging the juvenile black eagle was soaring with the adult eagles and would often follow the adults in flight. The juvenile would even sit in the three trees perching area near the public which was very uncommon.

We were however still surprised at how early the juvenile left the nesting area. There was not even the aggression from the parents as in the past. The young eaglet was seen in the last week of November 2003 and returned several times before leaving the territory mid December. The prior juveniles were often in the nesting area for 12 weeks, 17 weeks in 2001. This juvenile black eagle was only in the nesting area for 9 weeks. Little has been written about the Black Eagle post nesting period which makes it difficult to explain this unusually short period.

Urban Development
The development in the last year(2006/2007) has been immense and the eagles are certainly finding this very disturbing. The northern and southern borders of the Walter Sisulu National Botanical Garden have residential developments with no green belt available for migration paths for small mammals. With the future developments in the pipeline it will not be long before the Botanical Garden will be the only green space left in this immediate area. The project has observed adverse behavioural pattern for the latter part of 2003 and it is certainly man who is now the eagles main adversary. It is really surprising these tolerant birds stay in what has become a very unsuitable territory for eagles of their stature.


Waterfall with Black Eagles' nest to the left, identified by the white droppings left on the cliffs - Walter Sisulu Botanical Gardens, Roodepoort, Gauteng, South Africa

4 comments:

  1. Fascinating, you were so lucky to have an eagle nesting so close and for a young to fledge and survive is wonderful.
    We have almost tame hand raised Falcons in some of our vineyards to keep the grape eating small birds down, they wear radios on their backs so they can be kept track of, and some of them have nested in the open plains where there have been no NZ Falcons for many years. Always good to hear a success story!
    Oh yes, they sure do keep the small bird population in check around the vineyards too.

    ReplyDelete
  2. ...beautiful watercolor. What an interesting post...so full of information. I was sad when I got to the end to hear about development squeezing out the park. It's a shame there isn't a naturalist on all the building committees, to help buffer our wildlife.

    ReplyDelete
  3. Thank you Kelly, and thanks for visiting my site. Had a look at 'Red and the Peanut' - what a lovely site! Decided to follow your blog and your up-dates.

    For more information on the black Eagles, see the new post "Black Eagle Cam Project".

    Regards

    ReplyDelete
  4. How high does these black eagles fly, I am in a debate with a lady from the USA and she states that the black eagles is a low flying bird.

    Vincent

    ReplyDelete

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