Birds of Te Araroa Trail – Every Last Word

Natural history curator Dr Colin Miskelly completed Te Araroa Trail a year ago today. His epic mission was to count every individual bird seen and heard along the 3,257 km trail, from Cape Reinga to Bluff. He has now completed another marathon – analysing, writing up, and publishing his findings as a scientific paper. ‘Birds of Te Araroa Trail – Aotearoa New Zealand’s long pathway’ was published in the March 2025 issue of the journal Notornis, just 5 days ago. Colin shares the main findings here.

Bite-sized chunks

How do you describe and summarise everything everywhere all at once? That was my dilemma once I had all the Te Araroa Trail bird count data entered into a massive spreadsheet: 1,824 rows, 133 columns, and 38,222 cells with data, summarising 1,727 transects and 96 stationary counts that captured records of 106,483 individual birds of 111 species.

Then I realised that I already had the solution, based on the Te Papa blog series on the birds of Te Araroa Trail. The blogs were published at a rate of one a week as I wandered southwards, mainly using towns and cities as start and end points for each blog.

I chose most of the break points before setting out, to help readers visualise what part of the country I was writing about. I soon realised (much to my relief!) that this had the added advantage that there was usually furniture and electricity for those late nights and early mornings of blog writing at the end of each section, before it was time to start walking the next section soon after dawn.

These same towns and cities make logical start and end points for people who choose to walk the trail in sections, and also for thru-walkers to stop for a day or more to replenish their food supply and recharge their own batteries.

My revelation during data analysis was that these 19 sections, arranged from north to south, were manageable chunks of landscape that allowed bird communities to be compared and contrasted over the full length of Te Araroa Trail. Descriptions of the bird communities for each section meant that walkers could focus on just the section of interest (if a section-walker), or the portion of the country they would be traversing over the next week or so, rather than the mind-boggling enormity of contemplating the birds that they would encounter over the 4 months or more it takes to walk the entire trail.

The big picture

The most common bird question that I was asked about the trail was “What was the most common bird?” I didn’t know the answer until I crunched the numbers after completing the trail. I had kept running totals of the total number of species, the total number of individual birds, and the distance walked, but I chose not to keep running totals for individual species. I wanted there to be some surprises at the end!

I also didn’t know which species was the most frequently encountered overall – although I knew the likely contenders, as a few familiar names were among the top three species reported in blog after blog along the length of the trail.

Somewhat to my surprise, the most numerous species on the trail (and by a big margin) was the house sparrow | tiu, with 12,517 individuals. This was followed by chaffinch | pahirini with 5,806, and red-billed gull | tarāpunga with 5,427. Sparrows are super common in towns and cities, but are generally scarce in farmland and absent in forest and above the treeline. I didn’t expect their local abundance (with long stretches of zero or low counts) would be enough to make them the most abundant species overall.

Bird abundance was far higher in the North Island (41 birds/km) than in the South Island (21 birds/km), with an overall average of 33 birds/km. This was largely due to birds being more abundant (or more easily observed) in urban areas and farmland than they are in forest. Te Araroa Trail passes through far more cities, towns and farms in the North Island than it does once it crosses Cook Strait.

Chaffinch was the most frequently recorded species along the length of the trail (62% of the 2-km transects), followed by silvereye | tauhou (59%), and blackbird | manu pango (57%).

Southern limits

Each blog reported on new species observed in each section (i.e. their northern limits). However, it was harder to define southern limits for each species until I reached Stirling Point, south of Bluff. The scientific paper on birds of Te Araroa Trail includes a table summarising northern and southern limits for 30 bird species.

Examples of southern limits overlooked in the blogs were: brown quail | kuera (Puhoi), spotted dove (south-east of Waitomo), North Island robin | toutouwai (Whanganui River Road, near Atene), myna | maina (east of Whanganui), pheasant (Raumati), eastern rosella | kākā uhi whero (Wellington Botanic Gardens), weka (Deception River, Arthur’s Pass), and South Island robin | kakaruai (south of Mavora Lakes).

The answer to everything everywhere all at once

The scientific paper includes a graphic that compares the bird communities of all 19 sections at a glance – based on daytime transect counts of 106,207 birds of 106 species.

You will have to read the paper to find the detail of how the analysis was done, but the results can be interpreted if you know that the 19 transects are numbered from north to south (Cape Reinga to Kaitāia = 1), and that paler colours show bird communities that were very similar to each other. Cells above the line are comparisons between North Island sections; cells to the right of the line are comparisons between South Island sections; cells within the rectangle are comparisons between North Island and South Island sections.

The first section (Cape Reinga to Kaitāia) was the most distinct, largely because it was almost entirely coastal – down Ninety Mile Beach / Te-Oneroa-a-Tōhē – with no forest. The second section (Kaitāia to Kerikeri) was quite different from South Island sections, due to the abundance of a range of species that are rare or absent in the South Island (including myna, eastern rosella, pheasant, wild turkey | korukoru, peafowl | pīkao, Barbary dove, brown quail, and spotted dove).

Sections through the central South Island, between Lewis Pass and the Te Anau highway (sections 15 to 18), had very similar bird communities to each other. Abundant species for these sections included silvereye, Canada goose | kuihi, yellowhammer | hurukōwhai, black-billed gull | tarāpuka, and paradise shelduck | pūtangitangi, and frequent species included chaffinch, silvereye, dunnock, yellowhammer, redpoll, and skylark | kairaka.

Does predator trapping make a difference?

Te Araroa Trail passes through about 1,038 km of forest, of which about 233 km (22%) had well-maintained predator traplines. The presence or absence of traps made little difference to counts of most forest bird species, with the clear exception of tūī and kererū | New Zealand pigeon. Both these species were significantly more abundant in trapped forests, with tūī about 90% more abundant, and kererū 68%.

This will be little surprise to readers living in towns and cities (including my home town of Wellington) where predator trapping has led to dramatic increases in these two species. It also points to tūī and kererū being the best indicator species for community groups and conservation agencies wishing to demonstrate the effectiveness of their trapping effort.

How many black fantails?

Careful readers of the Te Araroa blog series will have noticed that I reported the percentage of black fantails for different trail sections in the South Island as ranging between 1.9 and 11.1%. Over the entire length of the South Island, I saw a total of 359 fantails, of which 20 (5.6%) were black. This is very similar to the 4.9% black that Kathryn Atkinson & Jim Briskie reported in 2007, and far less than the erroneous figure of “12–25%” and “Up to 25%” black reported in current field guides.

The figure of 25% is based on counts of fantails undertaken in Dunedin at the end of the Second World War by Isabella Tily and the Dunedin Naturalists’ Field Club. A summary published in 1947 indicated that they likely saw 15 black and 67 pied fantails = 18% black.

However, some shonky statistics published in 1955 (taking the average of three ratios, without knowing their sample sizes) reported the overall ratio as “in Otago, the proportion of black to pied forms is about one to four”, which is 20%. This clumsy wording apparently caused field guide authors to interpret this as one in four (25%) in 1966, and the incorrect figure has been repeated in field guides ever since.

Misinformation has a long half-life!

But wait, there’s more…

This summary splashes the surface of what I discovered on my hikoi. If you wish to dive deeper, please read the full paper:

Miskelly, C.M. 2025. Birds of Te Araroa Trail – Aotearoa New Zealand’s long pathway. Notornis 72: 33–48 https://doi.org/10.63172/221010tlsskz

Other blogs in this series

• Every Last Bird – the Birds of Te Araroa Trail
• Birds of Te Araroa 1 – Cape Reinga to Kaitāia
• Birds of Te Araroa 2 – Kaitāia to Kerikeri
• Birds of Te Araroa 3 – Kerikeri to Whangārei Harbour
• Birds of Te Araroa 4 – Whangārei Harbour to Auckland
• Birds of Te Araroa 5 – Auckland to Hamilton
• Birds of Te Araroa 6 – Hamilton to Te Kūiti
• Birds of Te Araroa 7 – Te Kūiti to Taumarunui
• Birds of Te Araroa 8 – Taumarunui to National Park
• Birds of Te Araroa 9 – National Park to Whanganui
• Birds of Te Araroa 10 – Whanganui to Palmerston North
• Birds of Te Araroa 11 – Palmerston North to Wellington
• Birds of Te Araroa 12 – Cook Strait to Havelock
• Birds of Te Araroa 13 – Havelock to St Arnaud
• Birds of Te Araroa 14 – St Arnaud to Boyle Village
• Birds of Te Araroa 15 – Boyle River to Rakaia River
• Birds of Te Araroa 16 – Rakaia River to Twizel
• Birds of Te Araroa 17 – Twizel to Wānaka
• Birds of Te Araroa 18 – Wānaka to the Te Anau Highway
• Birds of Te Araroa 19 – Te Anau Highway to Bluff