Can we help koalas survive our cities? A multi-prong approach to koala conservation in the urban environment

Caio Santos Neto

doi:10.25907/00878

Despite covering 0.69% of the Earth’s total land surface, urban areas can play an important role in species survival. However, urbanisation presents complex and evolving challenges for native species as they have to adapt to fast changing ecosystems. With land conversion to urban uses projected to double or even triple in the next 25 years compared to 2015, the pressure on local wildlife populations will significantly escalate. One of the most prominent concerns is the disturbance of animal movement. Urban development often results in habitat modification and fragmentation, reducing connectivity between habitat patches and altering the movement patterns of individuals across the landscape. Failure to rapidly adapt to this new environment puts wildlife populations at risk of becoming isolated in small habitat fragments, leading to numerous negative effects, such as increased disease spread, reduced resource availability and genetic erosion. To date, limited findings were reported on how connectivity can modify movement behaviours, habitat selection, and genetic patterns of habitat specialist and low-mobile species inhabiting urban ecosystems. This study explored the relationship between connectivity, habitat selection and movement patterns, as well as the impact of different land uses on movement behaviours and the genetic consequences of altered connectivity. We selected the koala (Phascolarctos cinereus) as a study case because they provide great opportunities for applying our insights to on-ground conservation efforts. Koalas are known for inhabiting urban environments and are currently under threat of extinction in three of the four Australian states and territories where they are found. As a low-mobile habitat specialist, they heavily depend on their ability to move through anthropogenic landscapes to access their specific food resource and locate suitable mates. Here, we monitored two populations of koalas living in urban and natural ecosystems. We predicted the connectivity of their habitats based on their real movement mechanisms, habitat suitability, and mortality risks. Using hidden Markov models, we unveiled movement behaviours from GPS telemetry data. Additionally, we explored how connectivity influenced the ability of koalas to move beyond their natal range, considering the degree of genetic relatedness (i.e., kinship) between individuals. Our findings indicated that koalas preferred well-connected areas as destination. In addition, the hidden Markov models suggested that koalas may adjust their movement behaviours in response to the diel pattern of human activities, but are less responsive to land use changes in their habitat. Furthermore, we provided further support to that notion that urbanisation restricts movements of male koala, forcing them to live near more related individuals. Altogether, our results illustrated that low-mobile habitat specialists may develop complex strategies to minimize the risks imposed by urbanisation, such as increased mortality and lower reproductive success compared to natural environments, despite facing restrictions when moving. They show preference for better-connected habitats, where the gene-flow is facilitated. Koalas, and likely other arboreal, low mobile, specialist species, may also perceive human activities as more threatening than modifications to the landscape, leading them to adjust their movement behaviours to avoid peaks of human activity periods, but not to human land uses. While this mechanism may decrease the likelihood of negative human-wildlife interaction such as vehicle collisions and agonistic human encounters, it might not fully mitigate the risks associated with reduced connectivity, like elevated inbreeding rates and the rapid spread of diseases. Our research offers valuable insights for effective connectivity mapping grounded in real movement data and tailored to the unique traits of specific wildlife populations. We emphasize that city plans and wildlife conservation initiatives should consider the risks associated with modified animal behaviour and evolutionary changes resulting from urbanisation. By accounting for these factors, conservation programs can better safeguard the survival of urban wildlife populations in the short and long-term.

Can we help koalas survive our cities? A multi-prong approach to koala conservation in the urban environment

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