Help for birds battling weeds

Invasive species are regarded as second only to habitat loss as a threat to birds in Australia, so new web-based tools to help choose plants to replace weeds with fleshy fruit will be a welcome relief to our feathered friends.

Weeds are an important conservation and economic problem worldwide. They directly threaten 16 native bird species on a national scale, although this figure is considered to be a substantial underestimate. New research suggests weeds threaten 25 bird species in NSW alone.

However birds contribute to this weed threat when they eat the fleshy fruit from these weeds and distribute the seed wherever they next roost. And so a new weed infestation can start up, many kilometres away from the source of the weed.

Dr Carl Gosper and Dr Gabrielle Vivian-Smith's Weeds CRC project, Selecting weed replacement plants for use by frugivorous birds, has come up with tools to help gardeners and land managers manage weeds but still keep their birds.

"Weeds greatly modify the habitat of birds by contributing to changes in fire regimes and vegetation structure, altering the quantity, quality and/or seasonal availability of food and ensnaring birds," says Dr Gosper.

"Weeds are well known for these negative impacts," he said, "but it is important to consider that there are also cases where weeds appear to benefit native species, or at least provide support for them, such as providing a source of food."

These positive ecological contributions by weeds can be a source of conflict in conservation management. Should the weeds be removed, or should they be retained because they support native birds and other animals?

Providing alternative food resources for birds can balance the impact of weed control, said Dr Gosper.

Providing alternative food resources aims to:

  • conserve populations of native fruit-eating birds following the loss of food resources from the removal of fleshy-fruited weeds
  • favour the native plants' seed dispersal and recruitment rather than the weeds'
  • reduce weed seed dispersal by promoting native plants that act as effective competitors for seed dispersal services (ie those provided by fruit-eating birds).

The tools developed by the Weeds CRC, for choosing native plants for fruit-eating birds comes in three forms. And they are all available on the web:

1. Replacement plant lists for target weeds:
Factsheets on Alternatives to bird-dispersed weeds in north-east NSW and south-east Qld and Alternatives to bird-dispersed weeds for Weeds of National Significance explain how fleshy-fruited weeds can be replaced by fleshy-fruited native plants as a food source for birds.

2. How-to guide for plant selection:
This comprehensive guide assists with choosing native replacements for weeds to support fruit-eating birds. This includes directions on selection based on traits. A variety of plant and fruit traits, such as fruit size and structure, fruit colour and fruiting season, are known to affect the food choices of birds. Using these traits can help identify which native plants have similar fruits to a selected weed, thus providing alternative food to a similar suite of native fruit-eating birds.

3. Native plant trait databases:
These databases have been provided as Excel spreadsheets, suitable for searching, sorting and extracting data. There is a database each for NSW, SA, Tasmania, Victoria and south-western WA.

"These tools will assist land managers, restoration practitioners, gardeners, nursery industry personnel and others choose replacement plants for these fleshy-fruited weeds," Dr Gosper said.

Editor's Note: Original news release can be found here.