fragmentation

Posted by Sam Heggie-Gracie @SamHegGra

It’s not easy being a city slicker; vainly calling over car noise, isolated from my friends in a small patch of forest, narrowly avoiding a cat (I’m allergic; also, see Sam’s post). And that’s just me. Urban birds must navigate these conditions too, and for them, it can mean the difference between life and death. By measuring a number of these pressures, I hope to elucidate which abiotic and biotic drivers mould the avian assemblages of Auckland city for my MSc.

Urban ecology studies are a relatively new area of research, as people around the world are increasingly drawn out of a bucolic lifestyle and into the jobs and excitement that cities can provide. The sprawling city of Auckland spans out from the concrete jungle of the CBD, through a gradient of increasingly green urban and suburban areas and onto rural outskirts. Our bird friends are found throughout, so I will be assessing the difference in bird abundances and composition across this environmental gradient. Additionally, I will be looking into what drives bird composition within urban habitat fragments. By assessing housing density, fragment size, noise pollution and a myriad of other urban characteristics, I hope to determine which of these are most important for providing a suitable home for our birds.

Tui Art by Cally Whitham https://www.behance.net/gallery/native-endemic/5061863

Previously, the words ‘all bird observations will occur between 5 and 9 am’, had filled me with much apprehension, but after overcoming the dread of waking at such an ungodly hour, I have become most earnestly committed to the birds of Auckland city and relish getting up to listen to the beatific morning chorus. Hoot hoot!

Sam Heggie-Gracie is an MSc student in the Centre for Biodiversity & Biosecurity, School of Biological Sciences, University of Auckland. He is investigating the drivers of bird composition in cities. He is supervised by Margaret Stanley and Cheryl Krull (AUT).

Posted by Carolina Lara @carislaris

I was recently asked by an engineer friend of mine what my PhD project was about. In my (failed) attempt to put it into simple words, I ended up giving him a large discourse on the topic. A couple of days passed and he got back to me to say “… I always thought biological systems were simpler”. I am new to this world of ecological networks, but simplicity is not a word that can be used to describe them. More specifically for animal-plant mutualistic networks, a set of animals interacts mutualistically with a set of plants that are connected to another set of animals that interact with another set of plants. Animals disperse a plant´s genes and get food as a reward, as in the case of pollination and seed dispersal ecosystem services.

Kereru (Hemiphaga novaeseelandiae), New Zealand’s native pigeon, feeding on Nikau Palm (Rhopalostylis sapida) fruit

The dynamics of these networks and how they are built have profound implications on the coexistence of species and moreover, they can give us insights about how resilient they are to human disturbances, such as habitat fragmentation. It has now been recognised that conservation efforts should not only be directed to species alone, but should also be extended to the interactions and networks they form. Loss of interactions would translate into loss of ecological functions and this could happen even before actual species extinctions, a concept known as extinction debt of ecological interactions. Daniel Janzen, a pioneer scientist in tropical ecology, stated more than 40 years ago that “what escapes the eye, however, is a much more insidious kind of extinction: the extinction of ecological interactions”. So, we really are talking about complexity when we talk about networks. And I’m glad I changed my friend´s perception of just how complex biological systems are.

Carolina Lara M. is a PhD Candidate within the Centre for Biodiversity and Biosecurity, School of Biological Sciences, University of Auckland. Her research interests focus on seed dispersal networks within fragmented landscapes. She is supervised by Margaret Stanley, Jason Tylianakis, Karine David, and Anna Santure.