A small step for koalas

I have been following certain developments on the koala front in Australia. The marsupial is an icon associated with Australia- and is also well known for its predilection for eucalyptus and sleep.

After a decline in the wild population (to approx. around 200,000 according to government figures), Tony Burke (Australia’s Environment Minister), following a Senate report, has listed koalas as ‘vulnerable’ species last week. However, the tag will be restricted to certain areas- i.e Queensland, New South Wales (both states experienced a heavy decline in population), and Australian Capital Territory (which now has no wild koalas), which is another example of effective lobbying by the industries concerned as both Victoria (which has the distinct Strzelecki koalas, most of which are in private properties) and South Australia are not included (Burke claims that there are large koala populations in these two states). Whilst NSW welcomed this development, the Queensland Premier, Campbell Newman, is disgruntled, labelling the move as a ‘mindless green tape’ and threat to the employment market and development in the state.

The Senate report associated the population decline with habitat destruction (mainly by coal mining, logging, and housing developments), climate change (drought and extreme weather resulting in bushfires), accidents (road-kill), attacks by dogs (especially in summer when they venture into gardens to drink from swimming pools and water bowls), and disease (notably: Chlamydia). In the case of bushfires, koalas’ slow-moving nature prevents them from escaping from fires.

The question now remains as to what will be done proactively to ensure that the koala isn’t driven to extinction.


Image source: BSPI/Corbis
Sources:


http://www.smh.com.au/environment/conservation/koalas-to-be-listed-as-threatened-amid-rapid-decline-20120426-1xo22.html

http://www.smh.com.au/environment/animals/youd-be-lucky-to-see-one-bid-to-protect-the-koala-20120430-1xv64.html#ixzz1tXMalDBm

http://www.smh.com.au/environment/conservation/koalas-get-some-protections-from-developers-20120430-1xtps.html#ixzz1tXMresPs

http://www.businessreviewaustralia.com/business_leaders/mining-boom-contributing-to-koala-decline

http://www.foxnews.com/scitech/2012/04/30/australian-govt-to-protect-koala-bears/#ixzz1tXLgGhYn

http://www.theaustralian.com.au/national-affairs/koala-listing-another-example-of-government-greentape-says-campbell-newman/story-fn59niix-1226342948508

http://www.environment.gov.au/biodiversity/threatened/pubs/guidelines-species.pdf

http://www.canberratimes.com.au/environment/koalas-protected-in-north-but-need-managing-in-south-20120430-1xu13.html#ixzz1tXM4mhNF

http://www.canberratimes.com.au/national/qld-slams-koala-move-as-mindless-green-tape-20120430-1xvfm.html#ixzz1tXN8svj7

http://www.abc.net.au/local/photos/2012/04/30/3491805.htm

http://www.abc.net.au/local/stories/2012/04/30/3492033.htm

http://www.abc.net.au/news/2012-04-30/koala-listed-as-vulnerable/3980216/?site=sydney
http://www.abc.net.au/news/2012-04-30/no-protection-for-victoria27s-koalas/3981160?section=vic

http://www.theage.com.au/victoria/victorian-koalas-left-out-in-the-cold-20120430-1xv2b.html#ixzz1tXMRlXGf

http://news.ninemsn.com.au/national/8459541/nsw-govt-welcomes-koala-listing

More scientific grub on migration

A previous post presented how those characteristic summer chorus of the English countryside may be soon an event of the past. This rapid decrease in the population of migratory birds in the UK was attributed to habitat destruction and other such anthropogenic factors, probably somewhere along the migration corridor. So what does habitat destruction and other anthropogenic influences bode for migrating organisms? Vishwesha Guttal and Iain Couzin, of Princeton University, try to predict this (amongst other interesting stuffs) via models explained in their paper on ‘Social interactions, information use, and the evolution of collective migration’, an interesting read, although a tad too technical for the layman.

Organisms, all along the phyla of the animal kingdom, are believed to migrate as a result of detecting and responding to factors governing resource availability. The foundational theory considers each migrating individual as “‘information processing units’, with interactions amongst them providing collective benefits”, such as improved migratory direction. Should an individual commit an error in the information processing, the aforementioned grouping would average the individual measurements, so as to deduce the mean migratory direction.

These migrating populations have two types of individuals:

-Leaders, who have a higher ability to detect and respond to directional gradient from the environment, but with weak (or none) social skills. They tend to occupy frontal or peripheral positions and expend more energy in trotting off the beaten track and facing dangers such as predators.
-Social individuals, who have strong social skills but weak ability to detect and respond to gradient. However, they utilise the strengths of the leaders for a free ride.

Population density, according to the model, is a crucial leverage factor. Extremely low-density populations (ergo, lesser probability of encountering others) comprises of leaders, thus resulting in solitary migration. Extremely high-density populations results in resident population due to a lack of migration (attributed to frequent ‘collisions among individuals’). It is when leaders and social individuals coexist that collective migration ensues. The bottom-line is that ‘the evolution of the migratory strategy (resident, solitary, or collective) is determined by the ecology of the species (i.e population density, habitat structure, costs and benefits of migration)’. Presumably, there could be other regressors as well....

Anthropogenic factors have been exerting pressures (such as habitat fragmentation and changes in population density) on the existence of many migratory species (examples cited in the paper includes: American bison and its steep decline in its population density; extinction of passenger pigeon) and migratory patterns (Blackcaps becoming resident; Eastern house finch exhibiting the reappearance of lost migration). As habitat fragmentation increased, the individuals adapt their migratory strategy by travelling longer distances to find an appropriate habitat. The researchers’ model predicted that in such cases, paradoxically, the population’s migration ability reduces relatively gradually with increasing habitat fragmentation. The reasoning is that: ‘at high levels of habitat fragmentation, no individuals evolve to be leaders, and therefore, the population loses its migratory ability. Even after restoring the habitat, a population’s migratory ability does not recover at the same habitat quality at which it declined due to the relatively short time scale of these changes’.

Guttal V, & Couzin ID (2010). Social interactions, information use, and the evolution of collective migration. Proceedings of the National Academy of Sciences of the United States of America, 107 (37), 16172-7 PMID: 20713700


Image Source: The Wandering Angel

Migratory bird species in the UK

I will always maintain that the loveliest spring and summer are experienced in England. Apart from the profusion of flowers and exceptionally pleasant weather, there was always a persistent backdrop of birdsong, regardless of whether I was in town or country, sidewalks or fens. This chorus now stands the danger of disappearing from the British Isles, as explained in the 2010 Breeding Bird Survey (BBS) report which lists the statistics of bird population from 1995 to 2010. But first the good news…

Good news:

- Two warbler species have reached their highest numbers in 15 years: Blackcap (+73%) and Whitethroat (+25%). The Whitethroat population had plummeted in 1969 due to the drought in Sahel (the arid zone south of Sahara where they spend winter), but have now risen probably due to increased rainfall in the region.

-Chiffchaff (+52%).

Bad news:
10 species have experienced a decline in population numbers between 1995 and 2010. Of these, 8 are annual migratory species which spend autumn and winter in sub-Saharan Africa and return to the UK in spring and summer for breeding (viz, turtle dove, cuckoo, nightingale, wood warbler, whinchat, yellow wagtail, pied flycatcher, and spotted flycatcher).

-Turtle dove: a decline of 74%, with 2009-2010 experiencing a slump of -21%.
-Nightingales: decline of -63%, with a -27% fall in the 2010 level from the 2009 levels. Now seen mainly in SE England.
-Wood warblers: -60%
-Whinchats: -55%
- Yellow wagtails: -55%
- Pied flycatcher: -51%
- Cuckoo: decline of -48%; Now more commonly sighted in Scotland than in England.
- Spotted flycatcher: -47%
The two non-migratory species which have shown a marked decline are:
- willow tit (-76%)
-grey partridge (-54%)

The trend is that relatively short-distance migrants (such as Blackcap and Chiffchaff which fly down to southern Spain and Northern Africa, without crossing Sahara) are doing better, whilst those that travel further (such as Turtle Dove, Cuckoo, and Nightingale) are showing a steady decline in population. The reasons are postulated to be habitat destruction (due to anthropogenic factors), desertification, hunting, and repercussions of climate change- but it is most likely to be a combination of many factors. Since the bird species’ migration corridor covers many regions/countries during the course of the year, the manifestation of any such factor anywhere could act as a leverage point.

* I apologise for any mistakes which might occur when one had taken a cocktail of medicines (am battling a wrist sprain, (another) bout of food poisoning, and an exceptionally torturous flu- all at the same time).

Image source: Scott Barrow/Corbis