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Our Goal

We aim to understand the seasonal movement of danaids across Hong Kong and the greater South China region.


To do so, we are using a large mark-release-recapture study in which we tag butterflies using paper stickers. Each sticker has a unique code and a URL at which sightings of the butterfly can be reported.

We are relying on YOU to help us report tagged buttefly sightings!

Our tagging programme:
a public mark-release-recapture study

In autumn and winter in Hong Kong, we catch danaid butterflies and gently adhere uniquely coded stickers to their right hindwings (mark).*


These sticker tags are 10 mm in diameter, waterproof, and lightweight (~7.5 mg, less than 3% of an average Euploea body weight). They do not harm the butterflies or affect their flight. Butterflies are released after receiving a sticker tag (release). 

Every sticker includes an URL, at which the public can report their sightings (recapture). The location and date of the sighting provides crucial information on the butterflies' migration route. 

Colour-coding: Butterflies tagged prior to winter (i.e., those not aggregating) have yellow stickers, while those tagged in winter aggregations have white stickers.

At the time of first capture, we also record identify and record the butterfly species, sex, wing condition, date and location of tagging for each butterfly. Follow the links below to view this data:

Butterfly data - 2022

Butterfly data - 2021

* Our researchers hold permits for field collection and research by the Agriculture, Fisheries and Conservation Department, HKSAR.


What is mark-release-recapture?

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

In 2022 and 2023, we will hold public butterfly tagging events to involve local communities our migration research. Stay tuned for more information!

In 2023, we will be holding schools visits to expose students to this amazing but fragile natural phenomenon and encourage their participation in science.

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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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