Studying the Flatback Turtles of Bare Sand Island – 2019

Written by: C. McGregor (u6079560)

In July of 2019 I had the privilege of spending a week on Bare Sand Island (BSI), volunteering with AusTurtle, observing the nesting female and hatching juvenile Flatback Turtles (Natator depressus). 

A newly emerged Flatback hatchling – Photo by author

Background
BSI is a small sand island located approximately 50km west of Darwin, Australia.  AusTurtle is a not-for-profit group, formed in 2004, that is dedicated to the monitoring and conservation of Flatback Turtles on BSI.  AusTurtle run research camps every year, over the peak of the nesting season, with the regular monitoring of the population enabling us to observe “the response of the nesting population and their eggs to changes in weather, initially, and more recently climate” (Guinea, 2019).  This is essential because despite the Flatback Turtle being a vulnerable Australian endemic species, little is known about them. 

Daily Duties
Whilst on the island, the volunteers had numerous duties each day.  Flatbacks nest at night, mostly around high tide, so our schedule was based around the high tides each day.  The first people began monitoring the beach for emerging turtles from 2 hours before high tide and when the first emerging turtles were spotted, the rest of the group then headed out in pairs to monitor different sections of the island.  We sat and waited until the turtles had dug their nests and begun laying, before we approached them.  The standard procedure was then as follows: measure the temperature of the eggs and the nest, record the serial numbers of the flipper tags (or attach new tags if needed), measure the length and width of the shell, record any defining features of the shell and record the GPS location of the nest.  All of this information was recorded on data sheets that were compiled the following day.  Finally, we would ‘cross off’ the turtle’s track to mark that the turtle and nest had been recorded.  This process was repeated for every turtle, until we were confident that there weren’t any more turtles nesting that night. 

The next morning, we had to be awake an hour before the morning high tide (5am on the first day!).  As a group, we would walk around the island checking for any nesting turtles and looking for any hatchling tracks or signs of an emerged nest.  If we found an emerged nest (indicated by hatchling tracks and a sunken patch in the sand), we would then dig up the nest.  We collected any hatchlings that were alive in the nest (to be released that evening), counted the number of empty shells (to determine how many hatchlings there were) and counted any unopened eggs.  The unopened eggs would then be opened to determine their ‘state’ (eg unfertilised, dead embryo, depredated, etc).  If there were more than 10 live hatchlings in a nest, we would take them back to camp to record details of the hatchlings.

Importance of Studying the Flatback Turtles of BSI
The research camps run by AusTurtle have helped to raise awareness about Flatbacks, with volunteers coming from around Australia and the world to work on BSI.  The data collected has been used to gain a better understanding of these turtles and how they are responding to changes in the environment, with numerous papers having been published based on Flatback data recorded on BSI.  Hopefully the information gathered about this species, on these research trips, can be used to inform strategies to protect this species.

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Hollow Hunting for a Superb Future

By u5825765

In recent years, Canberra’s rapid population growth has driven the development of new residential areas en masse. Burgeoning suburbs, such as Throsby, allegedly hold the key to accommodating such future growth. However, to the contrary of its boasted ‘superb’ development charm, the environmental impacts of Throsby (as an urban development) pose a threat to its own threatened regional avian icon: The Superb Parrot (Polytelis swainsonii).

Canberra: A future Superb centre

There is increasing evidence affirming the migration of Superb Parrots to Canberra as a result of climate change and loss of original habitat. In addition to other parts of Canberra, Throsby contains a significant area of suitable habitat in the form of mature-age trees. These trees offer vital hollows for the Superb’s nesting.

However, critically endangered Box Gum Grassy Woodland comprises much of this tree population – this being its own conservation issue of Throsby. According to Dr. Laura Rayner, one of the lead researchers of the ANU Superb Parrot Hollows study, this only emphasises the severity of the Superb Parrot’s future.

“In 50-70 years, this landscape — this area — is going to be the most important area for the population” – Dr. Laura Rayner, from her interview with ABC Journalist, Craig Allen

Setting up the climb

As part of my volunteer work, I assisted Giselle Owens – an astute researcher from Dr. Rayner’s team – in assessing Throsby’s mature-age trees for hollows and Superb Parrot populations.  My work primarily involved ground surveying and data scribing, recording Giselle’s observations and measurements as she ascended the trees.

We used a pre-mapped GPS database to locate the specific trees for surveying, as well as a comprehensive system of gear to aid Giselle’s climbing. In terms of plain sighting for potential trees, Giselle memorably remarked, “Generally, the worse they look, aesthetically, the more likely they have suitable hollows.”

Preparing the climbing system was the most time consuming part. At one tree in particular, we spent over half an hour just slinging the initial support rope over the tree. Repeating this process gave me a far greater appreciation of the sheer effort and time required to undertake such research.

In turn, I raised the question of how more modern technologies, such as lightweight drone cameras, could potentially improve research practices. Perhaps they could allow visual access to hollows without climbing, though such methods would need to be assessed in terms of potentially disruptive impacts.

Scribing and surveying

The task of scribing itself was relatively straightforward, though nonetheless a valuable experience. We measured a range of hollow aspects, such as location, condition, entrance size and depth. Our findings (per tree) ranged from none to more than half-a-dozen suitable hollows, as well as a ground survey of a tree with more than fifteen hollows. In addition to hollow diversity, it was interesting to see how the array of different measurements helped develop a more three-dimensional model of each hollow out of centimetre figures.

Ultimately, this profiling of hollows is not only important to informing population studies, but also potential future rehabilitation, such as improving current artificial hollow designs.

The data sheet used to scribe the aspects of each hollow. Note: I was unable to display/use data from the research due to formal restrictions (photo supplied by author).

Conserving a Superb future

Even from a short period of work, it is clear Throsby hosts a considerable habitat capacity for the Superb Parrot. To echo the arguments of existing research, it is vital that urban developments account for the situational gravitas of this threatened species. Ensuring earnest conservation for both a critically endangered habitat, and threatened species, should ultimately determine whether Throsby truly ‘makes life superb’.

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What environmental conditions do striped legless lizards prefer?

The striped legless lizard (Delma impar) is a vulnerable species in the Australian Capital Territory (ACT) under the Environmental Protection and Biodiversity Conservation (EPBC) Act. In the ACT, these lizards are usually found in the following areas: Gungahlin/Belconnen, Majura Valley, Jerrabomberra Valley and adjacent to Yarrumundi Grassland. These are mainly Natural Temperate Grassland communities, which are critically endangered with 99.5% of the community degraded. As such, the lizards face the same threats as the Natural Temperature Grasslands, which are degradation and fragmentation of habitat due to infrastructural development and agriculture.

Biodiversity offsetting

On two days in August and September, I got the chance to work with the ACT Parks and Conservation Environmental Offsets team. The team was working on their annual monitoring of the striped legless lizards at environmental offset sites, in order to better understand the distribution and abundance of their populations, as well as their preferred habitats. Such monitoring is very important to enable adaptive management, such that techniques to maintain these offset sites can be improved.

Home construction

The first day was spent laying down roof tiles that act as artificial shelters for the lizards. Each site had 5 clusters, with each cluster having 9 tiles in a 3 by 3 formation. They like hiding under these tiles as it is warmer underneath and they provide protection against predators. New survey sites were set up, and broken tiles from existing sites were replaced.

Unfortunately, we did not see any striped legless lizards on the first day, but we did see some three-toed skinks (Saiphos equalis), some Boulenger’s skinks (Morethia boulengeri), and plenty of cockroaches.

Open sesame

The second day spent with the team was for the actual surveying of reptiles found under the roof tiles. The site I went to was Gungaderra Grassland Nature Reserve, which is said to have the highest density of striped legless lizards. Before meeting any of the striped legless lizards, we were greeted with a juvenile blue-tongued skink, and also the highly venomous eastern brown snake (Pseudonaja textilis). Every roof tile I lifted up was a scary experience as we will never know what is residing underneath.

For each cluster of tiles, we had to take down the temperature, humidity, species and quantity of reptiles, whether they were juveniles, sub-adults or adults, and also whether it has lost its tail. Fortunately, we eventually got to see some striped legless lizards.

Using these results

Through the years of surveying and monitoring, the results show that the striped legless lizards prefer a mixture of grass between 10 and 20 cm high, which gives a variety of sites for shelter, thermoregulation and prey hunting. Such information derived from these surveys is essential in determining when grazing or burning should be carried out, so as to provide the best habitat for the lizards. With continuous improvement in the management of the lizards’ habitats, there is hope in the regeneration of the striped legless lizard population.

By U7025137

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Finding Striped Legless Lizards in a Threatened Ecosystem

Since European settlement, over 99% of Natural Temperate Grassland in Australia has been destroyed or significantly altered, making it one of Australia’s most threatened ecosystems.

Natural grasslands in the ACT provide essential habitat for a wide variety of invertebrates, reptiles, amphibians and birds, including 4 threatened species protected under the EPBC Act . One of these species is the Striped Legless Lizard (Delma impar). The Stripped Legless Lizard is a small snake-like reptile, inhabiting grasslands in parts of South Australia, Victoria and ACT (map). Once thought to be widespread across south-eastern Australia, in the ACT Delma impar is now constrained to sites which haven’t been significantly impacted by human activity, with populations mainly found in the Gungahlin district, Majura valley and Jerrabomberra Creek valley. Current populations of the species are small and isolated due to habitat fragmentation, with the species at risk from the threats of urbanisation such as clearing for developments, grazing, predation from cats and foxes, and the use of herbicides and pesticides.

Known habitat distribution of Striped Legless Lizard (Department of the Environment, 2019)

Monitoring Processes

I spent a day in September assisting with a monitoring process for the Striped Legless Lizard in several offset sites in the Majura valley region. Working with field ecologists from ACT Parks and Conservation Service, we collected data on the abundance of Striped Legless Lizards and other small reptiles across the sites. 

The monitoring sites consisted of clusters of roofing tiles laid out at different locations in the grassland to provide a form of habitat for the lizards to encourage them to shelter there. Our day was spent flipping over these tiles, counting and recording the number of Striped Legless Lizard (if any) as well as other creatures of note such as various skinks. Data on the weather conditions and tile temperature was also collected, as well as other variables such as tile heat.  

Quality of Habitat

The quality of habitat at the sites we visited was vastly different. In the initial sites, we found no sign of Delma impar as well as an almost complete lack of any other small reptiles. In these sites the ground cover was patchy, with shorter grasses and less coverage overall.

One of the lower quality monitoring sites, located in Majura valley

At a later site the ground cover was much denser, and at this site we recorded a number of Delicate Skinks (Lampropholis delicata) and finally spotted the only Striped Legless Lizard we managed to find that day.

A Three-toed Skink (Hermiergis talbingoensis) found at one of the sites. Unfortunately the Striped Legless Lizard moved too quickly for a photo!

The low vegetation quality of several of the offset sites we visited earlier in the day is concerning. Reptiles such as Delmar impar rely on a certain level of ground coverage to survive, preferring habitats with high grass structural complexity. With so much of their natural ecosystem already cleared for agriculture and development, it is imperative that the sites in which they still survive are maintained to a high quality. Sites set aside through the offsets scheme are often not of the highest quality, which presents problems from a conservation side. Although offsets are a valuable step towards mitigating some of the negative impacts of developments, high quality areas of vulnerable ecosystems such as Natural Temperate Grasslands must be prioritised.

u5801624

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Biodiversity Offsets: Canberra’s Ecological Prisons

Jake Adlam – u6078885

Biodiversity offsets were introduced to the ACT in the Planning and Development Act 2007, as a way of meeting environmental requirements established by the 1999 Environmental Protection and Biodiversity Conservation Act (EPBC). They have been growing in popularity in the ACT in recent years as a way of mitigating the impacts of urban development on critically endangered ecosystems such as Box Gum Grassy Woodlands (Box Woodlands) and Natural Temperate Grasslands (NTGs), and the various endangered species they support. Currently large parts of Gungahlin and the Molonglo Valley are protected and managed under this policy.

Environmental Offsets, ACT: Credit – ACT Gov

On the 19th and 20th of August I visited many of these offset sites with the ACT Parks and Conservation Service’s Environmental Offsets team. Our job, to set up survey sites designed to monitor for the presence of striped legless lizards (Delma impar), an endangered reptile species endemic to NTGs in the ACT. We spent many hours laying out large ceramic roof tiles, come spring time, the lizards make use of these warm ‘artificial refuges’ to stay hidden and raise their body temperature. Most of our time was spent removing old broken tiles from years gone by and transporting them to the tip, but in doing so we did spot many a reptilian inhabitant including three-toed skinks (Hemiergis talbingoensis) and some Boulanger’s skinks (Morethia boulengeri) as well, though sadly it was apparently to cold to be seeing any D.impar just yet.

Striped Legless Lizard (Delma impar): Credit – Bush Heritage Australia

Although it was heart-warming to see the dedication and passion of the Offsets team, and to learn from their wealth of knowledge and experience, I couldn’t help but feel disappointed at the reality of these offset sites in the ACT. Many of the sites we visited we’re heavily degraded, home to an over abundance of rabbits, stock and kangaroos, as well as a multitude of invasive flora including serrated tussock (Nassella trichotoma}, Chilean needle grass (Nassella neesiana) and various canary grasses (Phalris spp.). Although it is clear that management actions are being taken to lessen these pressures (weeding, culling, stock rotation, etc.) there are some issues that I cannot see being overcome.

Sheep surround our vehicle, Jerrabomberra West offset site

All the sites we visited appeared to me, akin to a wilderness prison, grasslands hidden behind tall fences and locked gates, isolated remnants of natural ecosystems sectioned of from the public and from each other. It seems to me that biodiversity offsets in the ACT create small, disjointed pockets of habitat, that lock in populations of endangered species, increasing the risk of genetic isolation and local extinction from stochastic events. Furthermore, tall fences keep these fledgling natural ecosystems out of site and out of mind for the ordinary Canberran, creating a distinct barrier between the city and nature. Sites near homes were plagued with dumped rubbish, a sign that locals don’t feel a sense of connection or ownership with these ecosystems. In short, our current way of selecting and managing biodiversity offsets alienates the community and isolates endangered species, a sustainable city should integrate these rare ecological communities into our everyday lives.

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Invasive Species Invading Jerrabomberra Creek Territory

u7034198 by Christian Piton

In September, I spent two weekends removing some of the invasive willow species found within the Jerrabomberra Wetlands Nature Reserve. The ParkCare ranger, who is a member of the ACT Parks and Conservation Service, was unsure of the exact type of introduced species of willow, but that it was brought into Australia by European settlers. The work I completed benefited the ongoing Jerrabomberra Creek restoration project that began in 2012 as a way to enhance the quality of ACT’s rivers.

What’s the Issue with Weeds?

The type of willow I removed and crack willow (Salix fragilis) are two weeds that are considered of national significance. They have the potential to easily spread, absorb nutrients, and take up space that native plants and shrubs need to survive. Early detection of willow is crucial to increase the chance of eradicating the species, but in most cases it is impossible to complete get rid of an introduced species. In addition, willows do not provide a suitable habitat for mammals or birds found at Jerrabomberra, and do not provide any food resources to local species. Invasive species cause not only a tremendous amount of damage to the environment, but also harm the economy. In Australia, it has been estimated that introduced species can cost approximately $13.6 billion a year. Therefore, it is important that people take any role in protecting native species and volunteer just a small of time to help minimize the destruction of reserves.

Image 1. The introduced willow

The Removal Process

My partner Floriane and I took turns alternating jobs with this simple yet tedious task. One of us would use the large pair of shears to remove the willow, and the other would immediately dab poison on the roots of the tree to prevent it from growing back. The herbicide that we used was called glyphosate and is also used on other invasive plants within the wetlands such as the black alder (Alnus glutinosa). After removal, the next step is to plant native trees and shrubs to increase the amount of diversity within Jerrabomberra. Unfortunately, the two days that I volunteered were rainy and the ground was too wet to plant seeds. However, the ranger said the next session in October will most likely involve planting common reed (Phragmites australis) seedlings near the creek to create habitat and stabilize the shoreline. 

Image 2. The removal of the willow
Image 3. Applying the herbicide immediately after cutting the willow
Image 4. The glyphosate used to poison the willow

Reflection

My time spent at Jerrabomberra taught me how serious of a threat weeds are to Australia’s environment. There needs to be more education on how to effectively manage weeds because so many people do not know how to correctly identify invasive species. This leads to people accidentally planting exotic species instead of native, and can also lead to a failure to remove introduced weeds early on. I also recognized from my two days that there were not many volunteers, but plenty of work to be done. I think that if everyone put aside a couple hours of their time every few weeks to help plant native species then many of the problematic invasive species would not be as out of control as today.

References

Environment, Planning and Sustainable Development Directorate – Environment. (2019). Willow control in Jerrabomberra Creek. [online]

Environment.gov.au. (2019). Weeds in Australia. [online]

Plein, M. and Shine, R. (2019). Australia’s silent invaders. [online] Australian Academy of Science.

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What’s Happening to the Trees?

Please follow the link to my blog “What is happening to the trees? Investigating snow gum dieback”. The link is here.

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