Effects of the Tasmanian Wedge-tailed Eagle on the Eco-system

Tasmanian Wedge-tailed eagle

The Tasmanian wedge-tailed eagle (Aquila Audax fleayi) is an endangered species due to human activities and is under the Tasmanian Threatened Species Protection Act 1995 (Parks.tas.gov.au 2014). These marvellous creatures have been subjected to recovery plans since 1992 and are very close to extinction with only 130 successful breeding annually. However, a few strategies have been input to spread public awareness. Keystone species are organisms that play a vital role in the ecosystem and have an effect on their environment in relation to their abundance. The Tasmanian wedge-tailed eagle is a keystone species because they are a top-class predator that has a key role to play in keeping the ecosystem balance under control etc. consumption of small marsupials and mammals.

Habitat Loss  

The Tasmanian wedge-tailed eagle is distributed in Tasmania, Australia. They live in a wide variety of habitats including dry forest sclerophyll, rainforest, grassland, and farmland. But breeding is limited to a variety of native forests of old growth, especially those dominated by Eucalyptus.  Land clearances and fragmentation is the leading cause of habitat loss for the Tasmanian wedge-tailed eagle because it decreases their accessibility to food and shelter. Deforestation has been occurring in Tasmania since 1803 changes elsewhere in Australia are threatening nearly every type of its natural habitat. As a result, the Tasmanian wedge-tailed eagle faces major conservation issues. These days, the land is cleared to make way for vegetation crops but when this is done only little bits of habitat is left for the Tasmanian wedge-tailed eagle and other inhabitants. Deforestation just drives endangered, threatened and vulnerable species to extinction. A method of resolving this issue is simply arranging an agreement between a business, organisation or enterprise to stop cutting down the trees and educate them on the importance of life.

Unnatural Death Causes

Unnatural death causes remain high. Australia’s biggest bird of prey is the wedge-tailed eagle. Farmers once saw it as a menace, convinced that eagles swooped down and carried lambs in their claws. Thousands of eagles have been shot and poisoned as a result. It is known that wedge-tailed eagles mostly take rabbits, and rarely eat lambs — usually dead lamb carcases rather than live ones. Although, in some parts of Australia, despite being a legally protected species, these majestic raptors are still being shot and poisoned. This subspecies experience a lot of mortality varying from shooting, poisoning, electrocutions and collisions with wind turbines, planes, and fences, this is sometimes called ‘unnatural mortality’. Studies estimated that 5 percent of adult eagles and 35 percent of juvenile eagles are killed by human contact each year.

Nest disturbances and other leading factors

Figure 1 indicates North-East Tasmania’s Bass Forestry District. The shaded regions show 38 percent of the forest categorized as possibly accessible for native forest harvesting and/or conversion of plantations as of 2001.

The Tasmanian wedge-tailed eagle is an endemic subspecies that belongs to the Accipitridae, Falconiformes, Aves, Chordata and Animalia family (Environment.gov.au 2019). It can grow up to 1m in length and can weigh up to 5kg with a wingspan measuring up to 2.2 metres. The Tasmanian wedge-tailed eagle is endangered due to various reasons. The main reason is that their breeding rate of success is low.  Tasmanian wedge-tailed eagles breeding season occurs from August to January. They often nest in high branches of eucalyptus trees and deserted areas to be isolated from potential predators. Unlike mainland wedge-tailed eagles, the female Tasmanian wedge-tailed eagle only lays one egg instead of two. Their nesting behaviour is a fragile process because they are shy breeders and any sort of subtle movement in their nesting area can easily scare away a female eagle from her fertilised egg. With human encounters, this is more frequent.

Statistics

Graphs shown below indicate that the Tasmanian wedge-tailed eagle is vulnerable to plantation establishment and native forest harvesting, meaning that 70 percent likelihood expectation of a 75 percent decrease at least once over 160-year period when all variables are included in the graph.

Figure 2 shows the pathway summaries under two management situations for the Tasmanian wedge-tailed eagle population, Scenario 1 (no harvest) and Scenario 3 (native forest harvesting and conversion to plantations to 2010). (Citeseerx.ist.psu.edu 2009)

Figure 3 shows the interval population limit risk curves under four management scenarios for the Tasmanian wedge-tailed eagle population. The dotted lines represent the likelihood of the population falling below 35 breeding adults under different situations (2 percent in scenario 1 and about 70 percent in scenarios 2, 3 and 4).

How will the loss of the Tasmanian wedge-tailed eagle impact humans?

The loss of such an important keystone species could lead to more damage for the

environment. The ecosystem could lose a lot of more species as a result. The role of the Tasmanian wedge-tailed eagle in the ecosystem is to balance the population of small mammals and marsupials. If the Tasmanian wedge-tailed eagle were to go extinct, their prey like rabbits for example could reproduce too much offspring making the population of rabbits too much for humans to handle and maintain. Having lots of rabbits roaming out and about could lead to them being listed as “pest”.

Conclusion

Dismissing the myths and learning about the importance of the wedge-tailed eagle has encouraged farmers to be more cautious and aware of their surroundings. More nests will remain active by encouraging foresters and landowners to keep in mind at least 10 hectares of bush around nest sites.

Bibliography

1. Environment.gov.au 2019, Aquila audax fleayi — Tasmanian Wedge-tailed Eagle, Wedge-tailed Eagle (Tasmanian), Australian Government Department of Environment and energy, viewed 30 May 2019  <http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=64435>.
2. Naturetrackers.com.au. n.d, Where Wedgie, viewed 30 May 2019, <https://naturetrackers.com.au/about.php>.
3. Jantos, J. 2014, 10 Australian keystone endangered species – Australian Geographic. Australian Geographic, viewed 31 May 2019,  <https://www.australiangeographic.com.au/topics/wildlife/2014/09/australias-keystone-endangered-species/>. 
4. Mooney, N. and Holdsworth, M. n.d, The effects of disturbance on nesting wedge-tailed eagles (Aquila audax fleayi) in Tasmania, Cabdirect.org, viewed 31 May 2019, <https://webcache.googleusercontent.com/search?q=cache:0n1Ig-7FsGUJ:https://www.cabdirect.org/cabdirect/abstract/19980600193+&cd=1&hl=en&ct=clnk&gl=au>.
5. Newgreenbusinessideas.blogspot.com 2012, New Green Business Ideas, viewed 31 May 2019,  <https://newgreenbusinessideas.blogspot.com/search/label/Keystone%20Species>.
6.  Parks.tas.gov.au. (2014), Parks & Wildlife Service – Wedge-tailed eagle, viewed 30 May 2019, <https://www.parks.tas.gov.au/?base=1001>.
7. Parks.tas.gov.au. 2014, Parks & Wildlife Service – Wedge-Tailed Eagle, Aquila audax. Viewed 31 May 2019, <https://www.parks.tas.gov.au/index.aspx?base=5121>. 
8. Birdsinbackyards.net. n.d,  Wedge-tailed Eagle | BIRDS in BACKYARDS, viewed 31 May 2019, <http://www.birdsinbackyards.net/species/Aquila-audax>.
9. Hentschel, T. 2016, ‘Deforestation in  ’, Prezi Presentation, Viewed 1 June 2019, <https://prezi.com/koxyjuf4_irw/deforestation-in-tasmania/>.
10. http://www.carterdigital.com.au, C. n.d, Wedge-tailed Eagle | BirdLife Australia. Birdlife.org.au. Viewed 1 June 2019,  <http://birdlife.org.au/bird-profile/wedge-tailed-eagle>.
11. Citeseerx.ist.psu.edu. 2009, ‘Modelling human impacts on the Tasmanian wedge-tailed eagle (Aquila audax fleayi)’, Viewed 4 June 2019, <http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.542.4739&rep=rep1&type=pdf>.
12. Staff, A. (2018). Scientists call on the public to look to the sky to help the Tassie wedge-tailed eagle – Australian Geographic, Australian Geographic viewed 4 June 2019, <https://www.australiangeographic.com.au/news/2018/03/scientists-call-on-the-public-to-look-to-the-sky-to-help-the-tassie-wedge-tailed-eagle/>.