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Our Goal

We aim to understand the migratory behaviors of danaid butterflies within Hong Kong and the greater South China region.


To do so, we are using a large, public mark-release-recapture study. We are tagging thousands of butterflies with stickers emblazoned with this website's URL. Observers of tagged butterflies can report the date and location of their sighting.

Public reports of butterflies allow us to collect valuable data on the timing and direction of danaid movements, as well as their longevity.

Our tagging programme:
How it works

We catch danaid butterflies and gently adhere uniquely coded stickers to their right hindwings. We are permitted to do so by HKSAR AFCD.


Each sticker is 10 mm in diameter and made of lightweight, water resistant paper (~7.5 mg, less than 3% of an average Euploea body weight). They do not affect the insects' flight. Every sticker includes an URL, at which the public can report their sightings, and a unique code corresponding to the individual butterfly. 

The colour of butterfly tags corresponds to the season: 

Green = Summer (Jun-Aug)

Yellow = Autumn (Sept-Nov)

White = Winter (Dec-Jan)

We also record the species, sex, and wing condition of each butterfly we tag, as well as the date and location of tagging. 

View our 2022 data

View our 2021 data



Afterwards, each butterfly is released to continue its journey.

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Mark-release-recapture studies

Mark-release-recapture studies are often used to study population sizes and dynamics, but they are also used in migration studies like this one.


In a mark-release-recapture study, animals are caught, marked, released, and recaptured after an interval of time. The proportion of marked to non-marked individuals captured can be used to estimate the size of the population.


Such techniques can also be used to determine the direction, distance, and speed of migration.

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Site survey and habitat monitoring

In addition to our tagging program, we are also monitoring known danaid overwintering sites to understand site selection, and population sizes and dynamics of danaids in Hong Kong.

Cluster site microclimates will be monitored to identify the environmental conditions favourable for butterfly clustering.

Education & outreach

Where possible in 2023-2024, we will hold public butterfly tagging events to involve local communities our migration research. Stay tuned for more information!

In 2023 and 2024, we are visiting Lantau schools to involve students in our research. Students will learn about butterfly biology and our research and participate in tagging and release of danaid butterflies.

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Our research is funded by the Lantau Conservation Fund. We are permitted by Agriculture, Fisheries and Conservation Department of Hong Kong (AFCD) for all butterfly handling inside and outside country parks.


We are permitted for entry to Siu Lang Shui by the Environmental Protection Department and to Lai Chi Wo by the Conservancy Association under the Management Agreement Scheme at Lai Chi Wo Enclave.

Reporting System

We want to determine the route and destination of these migrating butterflies. We can only do this with your help!


If you found one of our tagged butterflies, click here to report it!

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