In development · Not released · No download available
Footprint identification for New Zealand tracking tunnel cards.
Photograph a Black Trakka card or a DOC tracking paper. Inkspector finds the card and measures every print in real millimetres. It hands back a ranked shortlist with the evidence for and against each candidate, plus one thing to check.
Draw a line between the outermost toes. If it falls through or behind the central pad, you are looking at a rodent or a hedgehog. If it runs in front of the pad, you are looking at a mustelid. It is the sharpest single test in DOC's field guide, but the offset is hard to judge by eye on a faint print. Inkspector measures it and reports which way it fell.
Drag the plate sideways to compare →
All three drawn to one scale from the app’s own geometry, at the measured median size for each species. Print this page and they come out actual size.
Most cards will not carry enough to justify a single confident answer. What comes back is two to four candidates, each with its own confidence, the evidence both ways, and one concrete thing to check. Several species on one card is normal. Every one of them is reported.
Rattus spp.
High
Mustela erminea / nivalis
Medium
Anostostomatidae
Low
DOC's own field guidance is that prints too obscure to identify should not be guessed at. Where a set of marks will not support a call, the app reports it as unidentified.
Plus “no tracks”, “bait taken only” and “unidentified”. The DOC tracking index is worked out from presence or absence per species. That is what the app reports for each one.
Introduced Native
Ship, Norway and Pacific rats cannot be told apart by eye. The app reports “rat” and stops there. Stoat and weasel feet are a similar size, so the app offers the two together. Bringing natives back is the point of the trapping. A native print is called out when one turns up.
Dried flat, even light, square on. Get all four edges into the frame if you can. That gives the best scale of all.
A DOC paper is 173 × 95 mm. Current Black Trakka cards are 500 × 100 mm, 250 × 60 mm or 400 × 25 mm. Because those dimensions are known, an unambiguous outline with every edge in frame fixes the scale exactly. When an edge is cut off or the format is unclear, the phone measures how far away the card is and works the scale out from that. You can also set the scale by hand against something of known length. Either way, the prints come out in real millimetres.
Size, layout, the toe-line, toe counts and hair between the pads all feed the score. The reasoning is shown alongside each answer.
Runs on the phone Nothing uploaded About 2 seconds Needs iOS 26 or later
These are three real screens, following one photograph of a Black Trakka card from the picture through to the shortlist.
These are the current gaps being researched.
An outline of known dimensions gives an exact figure. Whenever all four edges are in frame, the app measures from those and leaves the phone’s estimate alone. The distance measurement assumes you are holding the camera square-on. A tilted or distant shot is reported back to you rather than used quietly. When no source can give a scale at all, size reasoning switches off and confidence is capped.
The sources are explicit that stoat and weasel feet are a similar size, so no photograph, however clean, will separate them on measurement alone. Counting the toes on a hind print is what actually tells them apart.
Ship, Norway and Pacific rats cannot be told apart by eye. The app reports “rat” and explains on screen why it will go no further.
Measuring across a heap of overlapping feet would produce a size belonging to no animal at all. Where prints pile up, the app flags them and sets the size evidence aside.
Wētā and beetle trails are currently ranked lower than they should be. That matters. Native species returning is the point of the trapping.
Every rule the app applies comes from a published guide or a measured study. The app cites them on screen too.