Blocks and flocks: why are some bird species so successful in cities?


Kathryn Teare Ada Lambert, University of New England

Life in the city can be stressful – for birds just as much as people. For humans, cities are expressly designed to put roofs over heads and food within easy reach, but the opposite can be true for many urban birds. They can find food and shelter harder to come by in the concrete jungle – with some notable exceptions.

For any species in any habitat, survival is about problem-solving and adapting to the environment. So what street smarts do city birds need? And why do some species, such as lorikeets, crows and ravens, seem to dominate our urban landscapes?

In general, urban birds must be bolder than those that remain in natural habitats, as can be seen by the boldness (or “habituation”) with which some species will forage for food with people nearby. But they also need to be able to avoid or retreat from unfamiliar objects or situations if they seem dangerous.

City birds also need to withstand exposure to a wide range of pathogens. A study of birds in Barbados found that urban birds have enhanced immune systems relative to their country counterparts.

While we have changed the environment in which some birds live, reducing resources in terms of food and shelter and increasing the number of pathogens that may impact their health, some birds have largely benefited from the new way of life.

Winners and losers

Within the urban ecosystem, there are winners and losers in the bird world. The suburban landscape, for example, now provides more nectar from flowers than native vegetation due to the gardens that people have established. This is a big help to nectar-feeding parrots such as Rainbow Lorikeets.

A recent study in Sydney found that the lorikeets benefit from the increased abundance of flowers in urban areas, and their numbers were higher in the leafy suburbs than in bushland.

Bold colours: Rainbow Lorikeets are among the most successful city birds.
Kathryn Teare Ada Lambert, Author provided

But if urban areas are such a rich source of nectar, why are some nectar-feeding species declining?

The Regent Honeyeater feeds mainly on nectar and other plant sugars. It has been seen in orchards and urban gardens, but is listed as critically endangered by the federal government.

This is partly because widespread clearance of woodland habitat has led to the increase of the aggressive Noisy Miner and Red Wattlebird. These species find it easy to “bully” other birds in open habitats. Noisy Miners have been observed pulling apart Regent Honeyeaters’ nests as they were being built.

Regent Honeyeaters, in contrast, are less adaptable to changed landscapes, because they are migratory and rely on detailed knowledge of existing food sources. If these resources are changed or removed, they may not have enough interconnected patches of habitat to move safely towards new resources – potentially leaving them vulnerable to cats, foxes and aggression from other birds.

Habitat loss can threaten some bird species or even leave them at risk of dying out if they do not locate alternative resources. The ability to find new food sources therefore becomes a valuable survival skill.

What’s more useful: flexibility or intelligence?

For some bird species, flexibility in finding food is crucial in making a successful switch to urban environments. One example is the Grey-crowned Babbler, which is endangered in Victoria, but my colleagues and I have documented it living in a suburban area in Dubbo, New South Wales.

This species usually nests in coniferous woodland and forages in the leaf litter beneath the trees. But in Dubbo, we saw these birds feeding on lawns, in playgrounds and even in leaf litter along a train track at the back of urban housing, sometimes visiting backyards along the way. This suggests that these birds can survive the loss of their woodland habitat by being sufficiently adaptable to life in the suburbs – as long as they can continue to find enough food, disperse between nearby groups and have access to native nesting trees.

Grey-crowned Babblers can adapt to new landscapes.
Kathryn Teare Ada Lambert, Author provided

For other species, such as crows and ravens, intelligence seems to be the key. These species can survive anywhere in the urban sprawl, including places where trees are scarce but rubbish bins are everywhere. Crows and ravens can literally pull food out of a bin and eat it – clearly a learned behaviour that has resulted from problem-solving.

These birds are highly opportunistic and social, allowing them to learn new ways of adapting to the almost complete removal of their natural environment.

Survive and thrive

What we can deduce from these examples is that some birds, like Rainbow Lorikeets and Grey-crowned Babblers, can adapt successfully to the urban sprawl as long as some characteristics of their habitat still remain. Other species, such as crows, have gone a step further and worked out how to survive purely on urban resources – effectively making a living in an environment that is completely unnatural to them.

This suggests that the more we urbanise an area without natural aspects, the less bird diversity we will have – and the more our urban areas will come to be dominated by those few species that are hardy, clever or adaptable enough to thrive.

Luckily, some councils in Australia and cities throughout the world are bringing the natural aspects of the forest back into the concrete jungle, so that a wider range of birds might survive here. More research is needed to work out exactly what each species will need, but planting more native plants is always a good start.

The Conversation

Kathryn Teare Ada Lambert, Associate lecturer, University of New England

This article was originally published on The Conversation. Read the original article.

Advertisements

Australia: Sheepdogs Save penguins


The link below is to an article that reports on a very successful experiment in saving Little Penguins on Middle Island in Victoria, Australia.

For more visit:
http://www.livescience.com/37097-dogs-protect-endangered-penguins.html

NSW Road Trip 2010: A Few Thoughts From the Road


It is now day 5 of the road trip and I have already covered almost 3000km. As you can appreciate covering that amount of territory in 5 days doesn’t leave a lot of time to Blog, especially when I have been trying to keep the website updated as well.

See the NSW Road Trip 2010 website at:

http://www.kevinswilderness.com/NSW/nswRoadTrip2010.html

What I thought I might do in this Blog is just pass on a few thoughts that have come to me while I have been driving around this great state of Australia – New South Wales. Let’s call this post, ‘A Few Thoughts From the Road.’

I have often thought that the governments of this country are wasting a great opportunity in promoting tourism in Australia. With such great distances to travel in Australia, wouldn’t it be great if the governments came up with an action plan to improve the rest areas throughout the country. Certainly some of them have been upgraded to a wonderful state – but then there is a lack of maintenance.

Many of the rest areas I have stopped at in the last few days have no facilities at all. Often they are nothing more than an overloaded garbage bin on the side of a road, with limited space in which to park.

To cut a long story short, I think Australia’s tourism industry would get a great shot in the arm if rest areas were improved across the country. It would also be good if hey could be located somewhere with a good view, an attraction, a small park for families, etc.

To go a step further (and this is perhaps pie in the sky), wouldn’t it also be great for the many Australians that drive throughout the country on camping/caravan holidays, if a percentage of these rest areas had some limited facilities for tents and caravans as well?

Perhaps a lot more people would travel around the country if such improved rest areas were created. There would also need to be some plan to keep the maintenance of these areas up to scratch also.

Another thing that militates against the travelling tourism that is fairly popular in Australia (it could be far greater), is the condition of many of the caravan parks across the country. To be sure, there are some excellent parks – but there are also a large number of parks that charge top dollar for run down facilities and grubby grounds. These poor operators need to lift their games to provide good facilities for their customers or they won’t get the return business that caravan parks depend upon. They need to spend a bit of money in order to make money.

I won’t return to a caravan park in which I had a bad experience – whether it be top dollar for run down facilities, poor service, poor attitudes of operators, etc. Some of these places just have no idea how to run a successful caravan park.

More thoughts to come – these will do for today.