Bird's-eye view

It's time to count the birds, because birds count! (11 minute read)

The grey bird above me seems far too small for the volume of sound which pours from its beak. Usually, I hear its long, melodious trills at a distance, but today there’s one just a metre away, and its call is resonant and clear. It begins with a few hesitant peeps, then comes the rising and falling trill which gives the bird its name, riroriro or grey warbler. It was the first bird I learned to identify by its song rather than by sight, and it remains a favourite.

I’m observing this specific riroriro in the reserve where I’m involved with planting and weeding, but I also hear, and sometimes even see, them in my garden at home. It’s one of a number of birds which keep me company when I’m outside. In fact, I occasionally even see one when I’m working at my desk, flitting among the branches of my hazelnut trees, which are right beside my window. I suspect that there’s some sap-sucking insect attracting them there, as I get sooty mould on my deck beneath the trees, a sign something above is producing honeydew.

The riroriro is one of New Zealand’s smallest birds. It’s about the same weight as a tītipounamu or rifleman, a mere 6 grams, about the same as a teaspoonful of salt. However, the tītipounamu has almost no tail, so it’s usually considered the smallest. Despite the riroriro’s diminutive size, it’s the main host¹ of the shining cuckoo or pīpīwharauroa, a bird almost four times its weight. That’s a bird I’ve never seen in my garden, although I do occasionally hear them in spring.

I didn’t have any decent photographs, so here’s a drawing of an adult riroriro being hassled by its pīpīwhararoa chick (image credit: Melanie Newfield)

Because New Zealand’s cities are largely dominated by introduced birds, they are mostly what I see. There are the bold blackbirds making their chip-chip-chip contact calls to one another as they dig for worms, uproot my seedlings or help themselves to my fruit. Before I got covered cat feeders, they even used to come into the house to steal cat biscuits if I left a door open. There are the ubiquitous, cheeping sparrows, starlings stalking along the ridge of the roof and a small flock of hyperactive goldfinches, rapidly twittering as they hurry from plant to plant. Sometimes, there are even a few eastern rosellas, colourful in red and bright green, in the tall tree next door.

However, because of all the predator control in Wellington, native birdlife is thriving too. As well as the riroriro, I often hear tūī singing, and far above me I hear the screech of the kākā almost every day. A flock of tauhou or silvereyes can often be seen among the twigs on my hazelnut trees, perhaps attracted by the same insects which bring the riroriro. Under certain weather conditions, I even hear and see karoro, or black-backed gulls, soaring overhead.

The birds I see and hear in my garden, as well as in the local reserve, are on my mind because there’s a citizen science event about to start – the New Zealand Garden Bird Survey. If you are in New Zealand, you can take part. I hope this article encourages you to do so.

The New Zealand Garden Bird Survey has been running since 2007, although in its current form it’s been going since 2014. Currently, it’s run by Manaaki Whenua Landcare Research, however this organisation will be incorporated into a new “bioeconomy” research organisation from the 1^st of July. I’m not sure exactly what will happen with the survey then. However, the more people who participate in the survey, the more likely it is to receive ongoing funding.

I have included information about how to participate in the survey at the end of this article. I’ve also put links to some other bird-related citizen science projects, including some in the USA, India and Australia. Before I get to that, though, I’d like to share some insights from past surveys and what they mean for our urban birds and for our urban ecosystems.

The main focus of the New Zealand Garden Bird Survey is to detect changes in abundance of 14 common species in urban gardens. This group doesn’t include the riroriro and some of the other species I see and hear. Although the information is collected, I haven’t been able to find published results for some species. However, the results for the 14 common species do include some interesting findings.

Firstly – and nothing to do with birds – is the fact that the number of people participating continues to rise. In 2014, just over 3000 reports were submitted. For several years, the figures hovered around the 3000-4000 mark, but 2020 saw a significant jump, to well over 5000. These numbers were maintained until 2024, when they jumped again to just over 7000. It does seem as if more and more people are interested in the birds around them.

Secondly, the trends for different species are different, showing that they aren’t all affected by the same factors. On the whole, the native species in the report are holding steady or increasing in some or all regions, although there are exceptions, which I will get to in a moment. However, the results for the introduced species are highly variable. Some long-established species are increasing, others are declining.

I’ll start with the native species, because the picture is fairly clear. The pīwakawaka (fantail), tūī and kererū are all increasing overall and in almost every region. Although the survey doesn’t tell us why the numbers have increased, it’s not wild speculation to suggest that this is the result of increased predator control around New Zealand.

There may be a change in that trend for kererū, which is showing a slight decline over the last five years. This potential decline was first detected in the 2023 survey, but it’s not in every region. In the wider Wellington region, for example, the kererū continues to increase, a finding backed up by the Wellington City Council’s monitoring, which uses a more formalised method. Declines in the North Island are seen in the regions most affected by Cyclone Gabrielle, which may indicate a link, although it doesn’t prove it. However, the largest decline is reported from Southland and Fiordland², and I don’t know enough about what has been happening there to suggest a reason. It’s probably too soon to know whether this is a sign of trouble or just a fluctuation due to weather or variability in food availability, but it gives us something to look out for.

Overall, the korimako (bellbird) and tauhou don’t appear to have increased or decreased over the last decade, but a closer look is interesting. Tauhou is doing well in some areas, such as Taranaki, and less well in others. Again the decrease is greatest in Southland. For korimako, there’s a clear north-south divide. It’s increasing or at least staying the same in the South Island, but declining in the North, including the Wellington Region. Since the korimako and tūī compete for food, it’s possible that the increasing tūī population is affecting korimako, although the largest declines in korimako don’t match the largest increased in tūī. If nothing else, it’s a reminder that while predator control is important, it isn’t a universal panacea which will save all our native birds.

The picture for the introduced birds is more complex. This isn’t only because some are increasing and others decreasing, it’s also because the value judgements we make about the increases and decreases are more complex. On the whole, we generally see increases in native birds as positive, especially because so few of them manage to thrive in urban areas. But this isn’t always the case for the introduced species.

As you might have guessed from my description of their behaviour, blackbirds aren’t always my friends. They are destructive in my garden, but I admire their audacity and I enjoy their company. Sometimes they are a serious pest, and sometimes they are a beautiful bird with a delightful song. There are different opinions about them, and so there will be different views on whether the overall increase in blackbirds is a good thing or not.

My favourite of the introduced birds is probably the goldfinch, at least in part because I like seeing them in a flock. I think they are pretty, I like their calls, and I also view their impacts as more positive than negative. They feed almost entirely on the seeds of introduced weeds, such as thistles, which aren’t a significant food source for any native bird, or any other native species, to my knowledge. They don’t appear to be either an agricultural or environmental problem here. So, I’m a little worried to see that they have declined quite significantly across New Zealand in the last five years. On the other hand, perhaps it’s a result of their weedy food plants declining, which isn’t a bad thing. I’ll keep allowing lots of plants to go to seed in my garden, so I hope I’ll continue to attract them.

The birds which have seen the largest increase, even more than pīwakawaka, kererū and tūī, is the largest of the introduced finches, the greenfinch. It has increased everywhere since 2014, although more recently it has declined slightly in some areas. This is a species I rarely see in my garden, although I do sometimes see it around. At first, I wondered why greenfinch numbers should be increasing so much, when it has been in New Zealand since the 1860s. Then I found an earlier survey from Wellington, covering the period from 1969-2006. Greenfinches followed the same pattern as most of the native birds in the survey, increasing considerably since the development of Zealandia and the introduction of widespread predator control. It’s not clear whether this is having any impact on native species or causing other problems. They are sometimes considered a pest here for their habit of eating the seeds of crop plants, but I haven’t found evidence that they are a major problem.

As I mentioned, I’m sure there are a wide range of different opinions on the increases (and decreases) in introduced birds. In my opinion, there’s one figure which stands out – the rapid increase in the number of common mynas in the Wellington region. Mynas were first introduced to New Zealand in the 1860s, with most initial introductions being in the South Island, although they were later introduced to Wellington, New Plymouth, Napier and Hastings. They were intended to control insect pests of agriculture, although they also eat fruit and seeds, so their introduction wasn’t necessarily appreciated. By 1900, only one South Island population persisted, near Nelson (this died out in the 1960s). They were also very uncommon in Wellington by the 1920s. However, they were also moving north, and became common in places such as Auckland. When I was growing up in Auckland, they were one of the most common birds.

By the 1960s, the myna was confined to areas above a latitude of 40^o south, a line which runs from just south of Whanganui and passes just north of Waipukurau in the central Hawkes Bay. Since mynas are native to tropical areas, it was thought than anywhere south of this line was too cold for them to persist. If they are now rapidly increasing in Wellington, does this indicate climate change? Or has the species begun to adapt?

I have always enjoyed the calls of the myna, and they are intelligent, engaging birds. However, they are aggressively territorial with other birds, and in Australia are associated with declines in some native species. Although there is no evidence that they survive in extensive areas of native forest, it is possible that they will have negative impacts on native and other introduced birds in urban and rural areas. The rise in mynas, therefore, may mean trouble for other birds. Just as the people of New Zealand have documented the rise in mynas, by contributing to the New Zealand Garden Bird Survey, we have an important role in documenting whether they are having an impact. So, if you have the chance, spend an hour sometime in the next two weeks to record the birds in your garden. You will be taking part in something special.

To contribute to the New Zealand garden bird survey, all you need to do is spend an hour recording every bird you see or hear in your garden. You can also do the survey in a local park.

How to take part in the New Zealand Garden Bird Survey

There is a tally sheet on the website, as well as identification resources. Additional images and recordings of calls can be found on New Zealand Birds Online and iNaturalist.

If you are in Australia, here is information about your garden bird survey, which takes place in October.

Aussie Bird Count – Aussie Bird Count 2025

India has an ongoing citizen science project to document birds.

Bird Count India - Citizen Science India

The USA has a programme which runs for the northern winter. In addition, there are other projects listed by the Florida Ornithological Society.

FeederWatch - Count Feeder Birds for Science

More USA resources

Citizen Science - The Florida Ornithological Society

Finally, there’s a global Backyard Bird Count in Feb 2026. I’ll give you a reminder for this one when it’s coming up.

Great Backyard Bird Count – Join us each February when the world comes together to watch, learn about, count, and celebrate birds.

1. For those not familiar with cuckoos, these are birds which lay their eggs in the nest of another bird. When the cuckoo chick hatches, it sometimes pushes other eggs out of the nest. In any case, the chick is raised by the birds whose nest it was laid in. New Zealand has two native cuckoo species, the more common shining cuckoo and the long-tailed cuckoo, which is found nowhere but New Zealand. In addition, several other species of cuckoo sometimes turn up in New Zealand.

2. Given the low human population in Fiordland, and therefore the small number of gardens for birds to be observed in, it’s more likely that this decline is driven by what’s happening in Southland.