Adult disguises

2 12 2019

Skilled ornithologists can tell the age of a bird by the look of its feathers. But many species are advancing the moult of their first adult plumage in response to global warming, and the youngsters look more similar to the adults now than two centuries ago.

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The clothes don’t make the (wo)man, but how we dress sends out a lot of information about our tastes, emotional state, or financial situation. In nature, where species have evolved to exploit all kinds of physical and chemical cues, visual communication determines a wealth of feeding and reproductive strategies (1).

Birds are familiar to all of us by the beauty and variety of their plumages (see extreme examples commented by David Attenborough here, here and here), which bird fans use to tell juveniles from males, males from females and breeders from migrants. In evolutionary time, birds have gradually moved away from tree-bark browns and tree-leaf greens and, due to functional requirements, modern feathers only span about one third of the colours these animals can perceive (2). They obtain yellows, oranges, and reds from carotenoid-containing food, dark colours from melanin pigment of own synthesis, and the so-called structural colours depend on how light reflects on the barbs of the feathers (2).

Plumage, across its entire range of designs, is a factor crucial to the life history of our feathery friends and, consequently, to evaluate how and how much anthropogenic climate change is impacting them (3).

Plumage and temperature

We know that mammals and birds are modifying their fur and feathers to optimise camouflage against landscapes with more or less snow (4), but less-known are the implications of climate change for feather moulting. Read the rest of this entry »





What is a ‘mass extinction’ and are we in one now?

13 11 2019

(reproduced from The Conversation)

For more than 3.5 billion years, living organisms have thrived, multiplied and diversified to occupy every ecosystem on Earth. The flip side to this explosion of new species is that species extinctions have also always been part of the evolutionary life cycle.

But these two processes are not always in step. When the loss of species rapidly outpaces the formation of new species, this balance can be tipped enough to elicit what are known as “mass extinction” events.


Read more: Climate change is killing off Earth’s little creatures


A mass extinction is usually defined as a loss of about three quarters of all species in existence across the entire Earth over a “short” geological period of time. Given the vast amount of time since life first evolved on the planet, “short” is defined as anything less than 2.8 million years.

Since at least the Cambrian period that began around 540 million years ago when the diversity of life first exploded into a vast array of forms, only five extinction events have definitively met these mass-extinction criteria.

These so-called “Big Five” have become part of the scientific benchmark to determine whether human beings have today created the conditions for a sixth mass extinction.

An ammonite fossil found on the Jurassic Coast in Devon. The fossil record can help us estimate prehistoric extinction rates. Corey Bradshaw, Author provided

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Victoria, please don’t aerial-bait dingoes

10 10 2019

Here’s a submission to Victoria’s proposed renewal of special permission from the Commonwealth to poison dingoes:

dingo with bait

08 October 2019

Honourable Lily D’Ambrosio MP
Minister for Energy, Environment and Climate Change
Level 16, 8 Nicholson Street, East Melbourne, VIC 3002

lily.dambrosio@parliament.vic.gov.au

cc:

The Hon Jaclyn Symes, Minister for Agriculture, Victoria

(jaclyn.symes@parliament.vic.gov.au)

Dr Sally Box, Threatened Species Commissioner

(ThreatenedSpeciesCommissioner@environment.gov.au)

The Hon Sussan Ley MP, Minister for Environment, Australia

(Farrer@aph.gov.au)

RE: RENEWAL OF AERIAL BAITING EXEMPTION IN VICTORIA FOR WILD DOG CONTROL USING 1080

Dear Minister,

The undersigned welcome the opportunity to comment on the proposed renewal of special permission from the Commonwealth under Sections 18 and 18A of the Environment Protection and Biodiversity Conservation Act 1999 (Commonwealth) to undertake aerial 1080 baiting in six Victorian locations for the management of ‘wild dogs’. This raises serious concerns for two species listed as threatened and protected in Victoria: (1) dingoes and (2) spot-tailed quolls (Dasyurus maculatus).

First, we must clarify that the terminology ‘wild dog’ is not appropriate when discussing wild canids in Australia. One of the main discussion points at the recent Royal Zoological Society of NSW symposium ‘Dingo Dilemma: Cull, Contain or Conserve’ was that the continued use of the terminology ‘wild dog’ is not justified because wild canids in Australia are predominantly dingoes and dingo hybrids, and not, in fact, feral domestic dogs. In Victoria, Stephens et al. (2015) observed that only 5 out of 623 wild canids (0.008%) sampled were feral domestic dogs with no evidence of dingo ancestry. This same study determined that 17.2% of wild canids in Victoria were pure or likely pure dingoes and 64.4% were hybrids with greater than 60% dingo ancestry. Additionally, comparative studies by Jones (1988, 1990 and 2009) observed that dingoes maintained a strong phenotypic identity in the Victorian highlands over time, and perceptively ‘wild dog’ like animals were more dingo than domestic dog.

As prominent researchers in predator ecology, biology, archaeology, cultural heritage, social science, humanities, animal behaviour and genetics, we emphasise the importance of dingoes in Australian, and particularly Victorian, ecosystems. Dingoes are the sole non-human, land-based, top predator on the Australian mainland. Their importance to the ecological health and resilience of Australian ecosystems cannot be overstated, from regulating wild herbivore abundance (e.g., various kangaroo species), to reducing the impacts of feral mesopredators (cats, foxes) on native marsupials (Johnson & VanDerWal 2009; Wallach et al. 2010; Letnic et al. 20122013; Newsome et al. 2015; Morris & Letnic 2017). Their iconic status is important to First Nations people and to the cultural heritage of all Australians. Read the rest of this entry »





The Great Dying

30 09 2019

Here’s a presentation I gave earlier in the year for the Flinders University BRAVE Research and Innovation series:

There is No Plan(et) B — What you can do about Earth’s extinction emergency

Earth is currently experiencing a mass extinction brought about by, … well, … us. Species are being lost at a rate similar to when the dinosaurs disappeared. But this time, it’s not due to a massive asteroid hitting the Earth; species are being removed from the planet now because of human consumption of natural resources. Is a societal collapse imminent, and do we need to prepare for a post-collapse society rather than attempt to avoid one? Or, can we limit the severity and onset of a collapse by introducing a few changes such as removing political donations, becoming vegetarians, or by reducing the number of children one has?

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“Overabundant” wildlife usually isn’t

12 07 2019

koalacrosshairsLate last year (10 December) I was invited to front up to the ‘Overabundant and Pest Species Inquiry’ at the South Australian Parliament to give evidence regarding so-called ‘overabundant’ and ‘pest’ species.

There were the usual five to six Ministers and various aides on the Natural Resources Committee (warning here: the SA Parliament website is one of the most confusing, archaic, badly organised, and generally shitty government sites I’ve yet to visit, so things require a bit of nuanced searching) to whom I addressed on issues ranging from kangaroos, to dingoes, to koalas, to corellas. The other submissions I listened to that day were (mostly) in favour of not taking drastic measures for most of the human-wildlife conflicts that were being investigated.

Forward seven months and the Natural Resources Committee has been reported to have requested the SA Minister for Environment to allow mass culling of any species (wildlife or feral) that they deem to be ‘overabundant’ or a ‘pest’.

So, the first problem is terminological in nature. If you try to wade through the subjectivity, bullshit, vested interests, and general ignorance, you’ll quickly realise that there is no working definition or accepted meaning for the words ‘overabundant’ or ‘pest’ in any legislation. Basically, it comes down to a handful of lobbyists and other squeaky wheels defining anything they deem to be a nuisance as ‘overabundant’, irrespective of its threat status, ecological role, or purported impacts. It is, therefore, entirely subjective, and boils down to this: “If I don’t like it, it’s an overabundant pest”. Read the rest of this entry »





First Australians arrived in large groups using complex technologies

18 06 2019

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One of the most ancient peopling events of the great diaspora of anatomically modern humans out of Africa more than 50,000 years ago — human arrival in the great continent of Sahul (New Guinea, mainland Australia & Tasmania joined during periods of low sea level) — remains mysterious. The entry routes taken, whether migration was directed or accidental, and just how many people were needed to ensure population viability are shrouded by the mists of time. This prompted us to build stochastic, age-structured human population-dynamics models incorporating hunter-gatherer demographic rates and palaeoecological reconstructions of environmental carrying capacity to predict the founding population necessary to survive the initial peopling of late-Pleistocene Sahul.

As ecological modellers, we are often asked by other scientists to attempt to render the highly complex mechanisms of entire ecosystems tractable for virtual manipulation and hypothesis testing through the inevitable simplification that is ‘a model’. When we work with scientists studying long-since-disappeared ecosystems, the challenges multiply.

Add some multidisciplinary data and concepts into the mix, and the complexity can quickly escalate.

We do have, however, some powerful tools in our modelling toolbox, so as the Modelling Node for the Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage (CABAH), our role is to link disparate fields like palaeontology, archaeology, geochronology, climatology, and genetics together with mathematical ‘glue’ to answer the big questions regarding Australia’s ancient past.

This is how we tackled one of these big questions: just how did the first anatomically modern Homo sapiens make it to the continent and survive?

At that time, Australia was part of the giant continent of Sahul that connected New Guinea, mainland Australia, and Tasmania at times of lower sea level. In fact, throughout most of last ~ 126,000 years (late Pleistocene and much of the Holocene), Sahul was the dominant landmass in the region (see this handy online tool for how the coastline of Sahul changed over this period).

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How to improve (South Australia’s) biodiversity prospects

9 04 2019
Fig2

Figure 2 (from the article). Overlaying the South Australia’s Protected Areas boundary data with the Interim Biogeographic Regionalisation for Australia layer indicates that 73.2% of the total protected area (excluding Indigenous Protected Areas) in South Australia lies in the arid biogeographic regions of Great Victoria Desert (21.1%), Channel Country (15.2%), Simpson Strzelecki Dunefields (14.0%), Nullarbor (9.8%), Stony Plains (6.6%), Gawler (6.0%), and Hampton (0.5%). The total biogeographic-region area covered by the remaining Conservation Reserves amounts to 26.2%. Background blue shading indicates relative average annual rainfall.

If you read CB.com regularly, you’ll know that late last year I blogged about the South Australia 2108 State of the Environment Report for which I was commissioned to write an ‘overview‘ of the State’s terrestrial biodiversity.

At the time I whinged that not many people seemed to take notice (something I should be used to by now in the age of extremism and not giving a tinker’s about the future health of the planet — but I digress), but it seems that quietly, quietly, at least people with some policy influence here are starting to listen.

Not satisfied with merely having my report sit on the virtual shelves at the SA Environment Protection Authority, I decided that I should probably flesh out the report and turn it into a full, peer-reviewed article.

Well, I’ve just done that, with the article now published online in Rethinking Ecology as a Perspective paper.

The paper is chock-a-block with all the same sorts of points I covered last year, but there’s a lot more, and it’s also a lot better referenced and logically sequenced.

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