The NZ Garden Bird Survey: Why do we love birds so much?

NZGBS Facebook group post

Google “Why do we love birds so much?” and of all offerings this one pretty much sums it up: “Any answer is correct”. Responses meander across scientific, technical, creative, aesthetic and spiritual realms – hardly surprising when birds are one of the most visible animals around us. As part of our everyday lives, we have embedded them into our cultures: from myth and legends… to branding for beer. So, why not sit down for an hour and count them? 40,000 people throughout Aotearoa already have!    

Ruru/morepork (Ninox novaeseelandiae ssp. novaeseelandiae). In Te Ao Māori (the Māori world), larger birds e.g., kahu (harrier) and ruru (morepork) acted as messengers to the gods, while smaller birds (pīwakawaka/fantail, toutouwai/robin and the mohoua/whitehead accompanied Maui when he sought to slay Hinenuitepo, the goddess of death (from Photo: Lynetteb (CC-BY-NC)

The Garden Bird Survey

It’s that time of year again – winter, wet and cold, when some of our manu Māori/native avians are drawn to our gardens to find food. You might see tūī, korimako/bellbirds, tauhou/silvereyes, pīwakawaka/fantails and riroriro/grey warblers. Wellington is a haven for kaka, while in Dunedin, kereru swoop though the heart of the city. The Garden Bird Survey (GBS) provides a snapshot of the health of garden bird populations and the wider environment by showing 5-10yr changes in bird counts across Aotearoa. Modelled on the UK Big Garden Birdwatch, the Aotearoa project was launched in 2007 through science agency, Manaaki Whenua Landcare Research. Along with providing a ‘citizen science’ opportunity for householders and raising public awareness of biodiversity and conservation concerns, local authorities can use the data to help with planning and managing their biodiversity responsibilities.

NZGBS Junior participant. Image sourced from the Science Learning Hub – Pokapū Akoranga Pūtaiao, University of Waikato,

Method and analyses

The annual event runs over 9 days (2 weekends book-ending a week). It’s easy to do: many birds (if not already familiar) are easily identified, data are easily collected on paper forms or entered online, and entries can be made from the comfort of your sofa (provided you have a good view of your back garden). The survey takes one hour with volunteers logging the highest number of individual birds of each species seen or heard (to avoid re-counting the same bird). Also recorded are in which region the survey was completed, whether the garden was urban or rural (according to the participant), if supplementary food was provided for birds, and if yes, what types (namely, bread, fat, fruit, seeds, sugar-water, and/or other), and whether the survey area included the area where birds were fed.

These extra layers of information add complexity for data analysis but broaden the way data can be interpreted. We can learn for example, the % of gardens occupied by each species, average number of birds per garden (for species recorded in 10% or more of gardens) and average number of each species per region (calculated from the sum of regional values weighted by the proportion of households in each region). Supplementary feeding is a complex topic – providing extra food can affect bird survival and reproduction rates, migratory patterns, and how bird communities are structured.

Post by Lesley Hughes Florence on the NZGBS Facebook group (very successfully!) feeding birds an apple in an egg whisk

To feed or not to feed?

In the first 4 yrs of the study, Spurr (2012) found two-thirds of survey participants provided supplementary food – not surprisingly more in the colder south than in the warmer north. We know that sugar water benefits tūī, korimako/bellbirds, tauhou/silvereyes. However, his study of also showed lower counts of tarāpunga/red-billed gull, warou/welcome swallow, kāhu/swamp harrier, kereru, Australian magpie, myna, tahou, goldfinch, karoro/black-backed gull, tūī, song thrush, and pīwakawaka above the median were lower in gardens where birds were fed than where they were not fed. Galbraith et al.’s (2017) detailed study of birds visiting garden feeding stations in Auckland showed house sparrows and spotted doves as the most frequent and numerous guests. The challenge lies with both being introduced species and understanding how their dominance at feeding stations affects native species. In other countries, similar projects have been set up specifically around supplementary feeding e.g., the Garden Bird Feeding Survey in the UK and the US/Canada Project FeederWatch.

A decade of data: a bird’s eye view

There have been 39,994 garden surveys completed since 2010. An overview of findings:

Manu Māori/native birds

  • Kererū: moderate increase nationally
  • Pīwakawaka/fantail: slightly larger increase nationally
  • Tūī (kōkō): shallow increase nationally
  • Tauhou/silvereye: shallow increase nationwide and moderate increase in Manawatū-Whanganui, Marlborough, and Taranaki

Introduced species

  • Myna: increasing in some regions, but rapidly increasing in Wellington
  • Starlings: moderate decline nationally
  • Song thrush, goldfinch and dunnock numbers no longer show national declines
Graphic from NZGBS illustrating bands for describing how the bird counts change over time

Keeping up momentum   

The NZGBS Facebook page is enormously popular – the public group now has 6,500 members, with various posts daily throughout the year. Contributors share photos and videos of birds taken on their own properties (often at feeding stations). Some photos are very high quality and offer insights into interesting or unusual bird behaviours. Questions are asked and answered on many different topics from “What’s this bird?” to seeking advice on supplementary feeding to understanding freakish occurrences such as melanism in blackbirds. Given the survey only happens once a year and for a very limited time, social media keeps community interest rolling while also providing a platform for shared learning.

The power of crowdsourcing!

Reporting the survey on national news (this year with added humour) is also a bonus. It shines a spotlight on the event and shows a growing acceptance that members of the public (with no formal science qualifications) can collect meaningful data and… that data collection can be fun! At the same time, reporting underscores how these types of national studies – especially those on private land – rely on public input to be successful.

Further reading

Spurr, E.B. 2012. New Zealand Garden Bird Survey – analysis of the first four years. NZ Journal of Ecology, 36:3 Available from:

Liberatore, A., Bowkett, E., MacLeod, C.J., Spurr, E., and Longnecker, N. Social Media as a Platform for a Citizen Science Community of Practice. Citizen Science Theory and Practice 3(1), p.3. DOI:

Galbraith, J.A., Jones, D.N., Beggs, J.R., Parry, K., and Stanley, M.C. (2017) Urban Bird Feeders Dominated by a Few Species and Individuals. Frontiers in Ecology and Evolution. Available from

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