The Effects Of Environmental Change On Birds — IELTS Listening Answers

“what wasn’t known until quite recently is that those that eat insects can also be affected.”

The gap names the birds' food: species 'that eat insects can also be affected', so insects is the diet word.

“these may be to do with the behaviour of the birds, or with the effect of mercury on the way their brain works, so whether it leads to problems with memory, for example.”

Effects may relate to 'the behaviour of the birds', so behaviour names what mercury alters, spelled behaviour or behavior.

“Now, the process of song learning happens at a particular stage in the birds’ development, and what you may not know is that a young bird seems to acquire this skill by listening to the songs produced by its father”

A young bird learns song by 'listening to the songs produced by its father', so father is the model parent.

“if young male birds are exposed to mercury, if they eat food contaminated with mercury, then the songs they produce aren’t as complex as those produced by other birds.”

Contaminated young males sing songs that 'aren't as complex', so complex describes the reduced quality of their song.

“it can affect their chances of reproduction.”

Mercury's effect on song 'can affect their chances of reproduction', so reproduction is the consequence for breeding.

“The lab-based studies have the advantage that you don’t get all the variables you would in a natural setting, so the experimenter has a much higher level of control”

Lab work removes natural variables, so 'the experimenter has a much higher level of control', which is the stated advantage.

“because many birds are migratory, they may be transporting mercury far from contaminated sites. For example, it’s been found that ducks who’d been feeding at a contaminated site were later shot by hunters over a thousand kilometres away, and presumably eaten.”

Ducks 'feeding at a contaminated site' were shot 'over a thousand kilometres away', showing mercury travels; the bird is duck.

“we also know that in humans, mercury causes developmental delays in the acquisition of language”

In humans mercury 'causes developmental delays in the acquisition of language', so language is the skill delayed.

“It’s now known that an unborn child can be affected if the food eaten by its mother contains high levels of mercury”

An unborn child is affected if 'the food eaten by its mother' has high mercury, so food is the route of exposure.

“It’s true there are new regulations for mercury emissions from power plants, but these will need billions of dollars to implement, and increase costs for everyone.”

The regulations 'increase costs for everyone', so the gap needs cost, meaning the money everyone must pay.