- Published: Wednesday, 20 February 2019 08:41
- Hits: 76
Researchers use thermal cameras to detect roosting birds
Where do small birds sleep? Mostly in trees is the short answer, but as so often occurs in ecology, there is more to the story…
If you were a bird, a few critical things might influence where you choose to spend the night. First and foremost, you don’t want to be eaten by a predator! And, if you want to get some rest, you can’t rely on alertness, speed and agility to escape owls or tree-dwelling mammals… So, concealment might be important. Second, you want to minimise your exposure to the elements. Smaller bodies burn kilojoules a lot faster than larger bodies, and cold winter nights can take a heavy toll on energy reserves so a thermally buffered location will also be desirable.
“For an activity that takes up a very substantial portion of a bird’s life, and where choices can mean the difference between life and death, we know surprisingly little about the ecology of sleep in birds” said co-author Rohan Clarke.
What little we do know is intriguing – for example within large communal roosts, complicated hierarchies exist where dominant birds take position at the centre of the roost - the warmest and safest position - while subordinate birds must take their chances at the periphery. While it’s relatively simple to investigate these behaviours in species that roost in large groups, it is far more challenging to even detect individuals that roost alone.
In an attempt to overcome this challenge, researchers from Monash University have been using infrared thermography, i.e. a thermal camera/scanner, to locate roosting birds of a wide range of species.
‘Thermal cameras measure heat emission. The difference in signal strength between an animal and the vegetation around it means that we can detect birds in total darkness. Another benefit is that the birds typically remain asleep, which means that this technique creates very little disturbance’, reports William Mitchell, lead author of the study.
To ensure that the technique worked, researchers carried out bird surveys during the day in an Australian woodland, and then repeated the same surveys at night using a thermal camera. They then compared detection rates of the two methods. 21 of 22 species that were commonly detected during day surveys were also found roosting at night.
“To date, we’ve recorded simple traits such as height and visibility of roost sites but this method really opens the door to dig deeper into the nocturnal behaviour of diurnal birds’ said Rohan Clarke.
“While there are some limitations, it’s great to get proof of concept for this method. We were able to quickly and efficiently detect roosting individuals for most species in our bird community with minimal disturbance” concludes William Mitchell
This research was recently published in The Journal of Field Ornithology:
Mitchell, W. F., and Clarke., R. H., 2019. Using infrared thermography to detect night-roosting birds. Journal of Field Ornithology. https://doi.org/10.1111/jofo.12285.
- Published: Wednesday, 28 June 2017 15:17
- Hits: 1156
Australian-bred Frigatebirds that migrate to Southeast Asian waters risk unacceptable levels of mercury contamination, according to a study led by Dr Rowan Mott.
The research, published in the Marine Pollution Bulletin, focused on two species of seabird that bred in Australian waters but migrated to Southeast Asia in the non-breeding period. The findings have serious implications for other species – including humans – using marine resources in Southeast Asia.
The researchers found that some of the sampled birds had feather mercury concentrations far exceeding those known to be harmful in other birds.
“Our findings highlight the need for tighter mercury emission regulations in southeast Asia,” said lead study author, Dr Rowan Mott, a researcher in the Monash School of Biological Sciences. “Tighter regulations would minimise the potential threat to frigatebirds and other species dependent on marine resources including humans,” he said.
The research team used seabirds as ‘bio-monitors’, and assessed environmental trace metal concentrations in the eastern Indian Ocean, between North Western Australia and Indonesia.
“We've been able to show that heavy metal burdens – namely mercury – in these birds almost certainly arises from Southeast Asia,” said Dr Rohan Clarke, study co-author and Research Ecology group lab leader at Monash University. “Mercury emission policy and enforcement must improve in southeast Asia,” he said.
Two breeding colonies in the eastern Indian Ocean were sampled: Ashmore Reef and Adele Island. Both locations support large breeding colonies of Lesser Frigatebirds, small numbers of breeding Great Frigatebirds, and are recognised by Bird Life International as Important Bird Areas.
The researchers looked for mercury contamination in the feather samples of 74 birds. “The results implicate mercury contamination in the marine areas of southeast Asia, and the South China Sea in particular, as a potential threat to seabirds,” Dr Mott said. “The findings highlight the difficulty conserving species that range widely and cross international borders,” he said.
- Published: Tuesday, 03 January 2017 11:45
- Hits: 1152
In a paper lead authored by Stefanie Rog in the journal Diversity and Distributions, the importance of mangroves for global, terrestrial vertebrates is revealed.
Stefanie conducted a review of the scientific literature published on mangroves, combined with open-source databases (WWF, ARKive and IUCN Red List).
The review found that 464 terrestrial species (320 mammals, 118 reptiles and 26 amphibians) use mangroves; five times more than previously reported. Of the 391 species whose conservation status has been assessed by ICUN, 35% were classified as threatened. Species were most often reported using mangroves for foraging habitat, followed by refuge, shelter, dispersal and breeding.
The highest alpha diversity of terrestrial invertebrates in mangroves occurs within Asia, northern Australia, West Africa and the Central American land bridge.
The terrestrial components of mangroves are often overlooked by society, and Stef's review extends our knowledge of mangrove forests and brings attention to these vital and undervalued ecosystems.
Read the full review in Diversity and Distributions here.
- Published: Tuesday, 22 March 2016 10:56
- Hits: 1613
New Monash University research has paved the way for drones to revolutionise ecological monitoring. Published in the journal Scientific Reports, the research found that drones are much more precise at monitoring the size of seabird colonies in tropical and polar environments than more traditional ground counts. Carried out on Ashmore Reef (tropical) and Macquarie Island (Sub-Antarctic), the research found that the ever-increasing precision provided by drones, along with the ability to survey hard-to-reach populations, may mean that wildlife monitoring projects move from traditional methods to drone technology.
Monash ecologist Dr Rohan Clarke explained that drones have already been used to monitor everything from the breeding success of canopy-nesting birds and to surveying elephants but nobody had yet tested if this method was better than more traditional survey techniques. “Until now, it has been unclear as to how precise drone technology might be when monitoring the size of populations of wildlife. Our latest research has demonstrated that a very high degree of precision can be achieved when using drone technology to monitor wildlife,” Dr Clarke said.
Lead author Jarrod Hodgson, who carried out the research while at Monash (and who is now at the University of Adelaide), explained how the research compared drone derived image counts with those made by humans on the ground. “Our team compared the precision of drone-derived image counts with those made at the same time by human counters on the ground for colonies of three types of seabird: frigatebirds, terns and penguins. Counters also monitored the colonies during the drone flights for signs that the birds may be startled by the presence of the drone,” Mr Hodgson said.
The authors found that counts using images captured by drones did not startle the birds and were consistently more similar than those taken from the ground. The authors suggest that the down-facing perspective of drone imagery reduces the likelihood of missing seabirds. In contrast, when counting from the ground, the terrain and other birds obscure the counters’ line of sight.
Dr Clarke explained the significance of these research findings to ecological monitoring projects. “It’s highly likely that in the future, drones will be used to monitor populations of birds and animals, especially in inaccessible areas where on the ground surveying is difficult or impossible. This opens up exciting new possibilities when it comes to more accurately monitoring Earth’s ecosystems,” Dr Clarke said.
- Published: Tuesday, 27 November 2018 08:58
- Hits: 53
Feather fouling or ‘oiling’ is a primary cause of seabird death during marine oil spills. When a seabird interacts with the oil at the sea surface the oil typically aggregates on the feathers to reduce both buoyancy and insulation. Because different oil products and different oil spill volumes result in different oil film thicknesses, the outcomes for seabirds can vary.
A study undertaken by honours student James Matcott investigated the impacts of different oil film thickness on feather structure and integrity using feathers collected from a large number of tropical and temperate seabird species.
Under laboratory settings, feathers of seabirds were exposed to either crude and condensate oil films of varying thickness. Feathers were then measured for changes in mass, and for changes in feather structure (specifically barbule clumping as can be seen in the image of a highly magnified feather).
We found that there was a threshold response to oil film thickness, with oil films equal to or greater than 3µm leading to increases in both feather mass and clumping. “This finding shows that very little oil is required to damage the structure of seabird feathers”, reports James Matcott. Nevertheless, when oil films are especially thin at the sea surface (i.e. < 3µm) they may have relatively little impact on feather structure and integrity.
This finding provides new insight regarding the threat that oil spills pose to seabirds. “It shows that oil film thickness is an important consideration when devising response strategies that aim to minimise further harm to seabirds and other organisms in the event of an oil spill” said Dr Rohan Clarke.
For the full report, see: https://www.sciencedirect.com/
- Published: Wednesday, 28 June 2017 15:02
- Hits: 1215
Co-authored by Rohan Clarke
Australia’s avifauna is large, diverse and spectacular, reflecting the continent’s impressive range of habitats and evolutionary history. With specially commissioned paintings of over 900 species, The Australian Bird Guide is the most comprehensive field guide to Australian birds ever seen.
The guide features around 4700 colour illustrations, with particular emphasis on providing the fine detail required to identify difficult groups and distinctive plumages. Comprehensive species accounts have been written by a dedicated team of ornithologists to ensure identification details, distribution and status are current and accurate.
The Australian Bird Guide sets a new standard in field guides, providing an indispensable reference for all birders and naturalists looking to explore Australia’s magnificent and unique birdlife.
To learn more about the book visit CSIRO Publishing.
- Published: Friday, 02 September 2016 11:09
- Hits: 1241
August was a busy month for three of the Phd candidates in our group, with Katherine Selwood, Rowan Mott and Shane Baylis all presenting the final seminars of their PhD candidature. Katherine also submitted her thesis titled "The significance and future prospects of floodplains for birds in a drying climate", and will soon commence a postdoctoral position at University Of Melbourne. We wish Kat the very best in her new research position.
Both Rowan and Shane plan to submit their thesis later in the year. In the meantime Rowan has been awarded a writing scholarship to complete his manuscripts for submission to scientific journals, and Shane is planning a cycling trip around Tasmania during November with his partner Nancy.
- Published: Friday, 09 May 2014 15:49
- Hits: 3574
Research Ecology, led by Rohan Clarke, is partnering with ConservationDrones to use Unmanned Aerial Vehicles (UAVs or drones) for seabird monitoring. The Research Ecology team recently returned from a successful trip to remote islands in north-western Australia where high resolution images of nesting seabirds were captured using a UAV.
After some preliminary testing, we discovered that we could fly at an altitude of 75 m above ground level (agl) without causing disturbance to the birds in these environments. We also found that flying at lower altitudes would work for some large nesting species, but smaller non-nesting species were easily flushed from perching sites by the UAV at such heights.
We targeted colonies of Crested Tern and Lesser Frigatebird for aerial survey. The Crested Tern colonies represent a medium-sized species that nests in dense colonies on the ground, whereas Lesser Frigatebirds are a large seabird which nests in smaller groups typically on elevated nest stacks and within vegetation. For every successful survey, experienced seabird counters made 1 or 2 blind counts of the surveyed population. Research Ecology will be comparing these ‘ground counts’ with UAV aerial counts to assess the reliability of UAV data.
Research Ecology is continuing to refine techniques which will allow for lower impact and more reliable aerial surveying of vertebrates. We are excited to continue our collaboration with the ConservationDrones team in several upcoming projects.
- Published: Sunday, 30 September 2018 14:14
- Hits: 37
The charismatic Mallee Emu-wren, once widespread in the Murray-Mallee region of South Australia and Victoria, has in recent decades, been restricted to a small network of Victorian reserves by a series of bushfires.
Mallee Emu-wrens are specialised to live in hummock-grass vegetation, and while this key habitat eventually regenerates following fire, Mallee Emu-wrens have no capacity to recolonise such areas.
Another large-scale bushfire could push the endangered Mallee Emu-wren past the point of no return.
They have just recently been involved with the successful translocation of an additional 38 birds back into Ngarkat Conservation Park in South Australia.
“In 2018, 78 Mallee Emu-wrens were translocated from Murray-Sunset and Hattah-Kulkyne National Parks in Victoria to Ngarkat Conservation Park as part of a trial to determine the suitability and effectiveness of translocation as a conservation strategy for the Mallee Emu-wren,” said Dr Rohan Clarke.
“Using this translocation as a model system, we are looking at which planning, implementation, and long-term monitoring can be improved in translocations of threatened species,” he said.
PhD candidate Will Mitchell said tracking of the released birds was difficult given their tiny size and elusive behaviour.
“We were blown away when we found a significant number of paired birds with young fledglings,” he said.
Will hopes that a key outcome of his research will be to provide a framework for conservation managers to assess how many individuals can be removed sustainably from a population for the purpose of translocation.
“At a local scale, the successful re-introduction of the Mallee Emu-wren to Ngarkat Conservation Park will increase the global population of the species, provide an insurance population against further catastrophic wildfires in currently occupied Mallee Emu-wren habitat, and pave the way for larger-scale re-introductions into other reserves from which the Mallee Emu-wren has become extinct,” Will said.
- Published: Tuesday, 03 January 2017 11:53
- Hits: 1127
Lab member Rowan Mott recently had a paper from his PhD research published in The Auk, which highlights his findings on how two similar congeneric seabird species can successfully breed side by side.
Traditional research methods document high levels of resource overlap in Great and Lesser Frigatebirds. Rowan used high-tech GPS tracking combined with chemical analysis of blood and feathers, to identify previously unknown differences in dietary and spatial aspects of the foraging strategies of these two species. The results indicate that body size differences between the two species influence the tropic level of the prey consumed, with the larger-bodied Great Frigatebirds taking prey higher on the food chain compared with the smaller Lesser Frigatebirds. During the breeding period, when adults are spatially constrained by the need to attend to an egg/chick, there exists considerable spatial overlap among species and sexes. However during the non-breeding period, when the demands of rearing a chick are removed, this overlap diminishes, with males of both species foraging further afield in offshore waters.
Read The Auk's blog about Rowan's research paper here.