Transcript

Part 4.

Part 4.

You will hear part of a lecture on bird research in Australia.

Good afternoon.
This is the third session of the series of lectures on wildlife.
For this lecture, we’re going to look at two studies on the habitats of birds and protection measures taken in Australia, including the basic methodology and related areas of research.

Now, let me give you some background information about the first research project on birds.
The study was carried out by R. B. Cunningham and his team from the Australian National University in 1995.
The primary goal was to detect the breeding habits and resting sites of some birds, especially those protected species in urban regions.
These species included birds like peregrine falcons and kestrels in Australia.

The bird dataset consisted of a total of 153 species, recorded from 946 sites.
One might expect that in order to obtain valid data on their distribution patterns and population densities, researchers had to count through binoculars.
Instead, they managed to estimate with various standard distance sampling methods like random sampling.
In addition, a mapping system was used to study their companionship behaviour.
It recorded proposed birds’ nesting sites to monitor the mating behaviour of targeted species.

To obtain valid data of birds’ whereabouts, researchers attached identity tags to birds’ legs transmitting radio signals.
The tagging process was done when the birds were between 5 and 7 days of age.
After the initial tagging, data was collected from subsets of radio-tagged birds, making it possible to assess the trends of birds over 15 months.

So, what did they find?
Well, as it turned out, many of the birds tagged had the tendency to nest in the same habitat where they grew up.
Their nesting sites were quite varied and included freshwater reed beds, tidal reed beds, agricultural crops and man-made sites.
Even though naturally occurring nests were common, birds sometimes accidentally nested in man-made devices like power towers, chimneys and tunnels.

This research also studied the impact of humans on bird communities and found out that pollution had contributed greatly to the declining birth rates of some species, which were considered to be extinct or threatened to vanish from the study area.
These species are dependent on natural forests because of their breeding holes.
They will become extinct when local natural forests continue to be polluted heavily.

A number of measures were thus taken by members from local animal conservation organisations to boost their alarming survival rates.
Firstly, breeding boxes were placed in trees taking on the role of breeding holes that were contaminated.
Protection guidelines were also introduced strictly prohibiting killing, disturbance and habitat destruction.
A further measure was taken to ensure the safety of birds from wind farms.
In fact, birds are sometimes shedded by wind turbine blades.
A great deal of work was done on how to prevent them from colliding with turbines.
A case in point was protecting space for bird migration by ensuring that migratory routes were kept free.

Falcons generally cope well with wind turbines but not in weather conditions where visibility is bad.
So, with knowledge of how fast falcons fly, bird stations in northern Australia can notify wind farms further south of the falcons’ approach so that turbines can be shut down as they pass by.

Then, another piece of research was done a couple of years later by Conway in 2006.
His team detected the calling frequency of seabirds flying at night.
Acoustic signals are important communication tools for birds.
These signals can indicate social cohesion, prey location and breeding behaviour.
Courtship songs are common among various species during mating seasons.
Males produce calling songs that attract distant females, and then courtship songs will induce nearby females to respond.

Surveyors also took recordings of the sounds of all the individual birds detected.
A tablet PC was used to process detailed information like sound pitch, spectrum, length and timing of surveys.
To minimise the disturbance on the bird community, all the sounds were recorded from a distance using microphones to detect noise.

They found that the probability of call events was much higher for solitary birds communicating early and late in the day.
Further analyses indicated that during foraging, the frequency of calls was significantly greater for birds encountering schooling fish, and birds called sooner after a catch in these foraging scenarios compared with when only single fish were encountered.

The results of this study showed that increased calling activity in the presence of more profitable prey could be of crucial importance to seabirds that benefit from group foraging.