Today I decided to take another tour of the local university. We went into the science department first.

Suddenly, I found myself harassed by a woman in a lab coat. She exclaimed in an urgent voice, 'My experiment's gone!'

'Gone where?' you ask.

'I don't know, just gone!'

Last time you were pulled out of the tour in the mathematics department, it looks like it's going to happen again. She drags you towards a nearby laboratory.

As you go, you realise she's holding a stack of papers about birds. 'What's those?' you ask.

'I'm a birdwatcher in my spare time. I was collating my club's observations from this morning.' Opening the door, she gestures to a box in a lab. 'Look! Nothing!' You realise that's not the whole truth, as you pick up a scrap of paper she's dropped on the floor. You drop it again just as she spins to usher you out again.

What's in the box?

What you can see of the papers she is holding (___ indicates a gap of arbitrary length):


  • Bir___rved to be fly___ocks with usu___ormat___n.
  • Leng___ails:___ound 45 me___
  • Ta___gle fr___avel direc___bout 25___rees
  • Spee___tra___: aro___ 20 m___s pe___ute, in ___aight lin___
  • Floc___lew at di___ent heig___

The scrap on the floor:

Sighted flocks on metre grid centred at Point Zero:

( 200, 680)   S    0926
( 330,-420)   N    0937
( 110,-180)   N    0949
(  70, 120)   S    0954
( 290,  80)   N    1002
(- 10,  20)   W    1007
( 250,-300)   S    1015
(   0, 440)   N    1020

Press Release!


Massive congregations of birds have been seen flying past the city centre recently! Watch out for airborne droppings!

Another hint:

Obviously the birds need to make a message somehow. Where?

This story is based on a fictional event and taken from there...

Part of an upcoming metapuzzle.

  • $\begingroup$ There must be something that affects the way the birds fly (like food, a magnet or a smelling substance). $\endgroup$
    – Nautilus
    Commented Apr 16, 2017 at 9:40
  • $\begingroup$ @Nautilus That's getting a bit complicated :P $\endgroup$
    – boboquack
    Commented Apr 17, 2017 at 7:51

3 Answers 3


The box contains ...

... a vacuum.

Or, in the language of the birds:

strange formations when birdwatching
This is the pattern the formations have at 10:00 hours.

Nautilus and tmpierce have already worked out what the gaps in the notes mean. With the help of these notes we know the uniform speed of the formations. The formations have the typical V pattern. The 45m length and the angle of 25° corresond roughly to distances of 40m in flight direction and 20m perpendicular to that.

The note that says that the formations have different altitudes is just to rule out that they collide. (The hint about droppings first made me think that the message were written on the ground, in which case the exact altitudes would have mattered. The birds here are well behaved and continent, though. Phew!)

Note that the above image is the view from the ground. The top view is mirrored.

  • $\begingroup$ Great job! BTW, how did you get the bird to act as random points? Mathematica? $\endgroup$
    – boboquack
    Commented Apr 24, 2017 at 13:49
  • $\begingroup$ No, it was a quick-and-dirty piece of Javascript that draws stuff on a canvas element. My first draft used straight lines. $\endgroup$
    – M Oehm
    Commented Apr 25, 2017 at 17:14

Partial solution:

The papers she's holding read...

Birds observed to be flying in flocks with usual formation.
Length of ...ails: around 45 meters
Ta... angle from travel direction: about 25 degrees
Speed of travel: around 20 meters per minute, in straight lines
Flocks flew at different heights

  • $\begingroup$ A couple of errors: trails and takeoff (incidentally, they are meant to be the same word) and the thing I just changed (made a mistake) - seconds to minutes. After this, think about the whole picture. $\endgroup$
    – boboquack
    Commented Apr 17, 2017 at 7:51


Continuing the partial answer by @Nautilus

I suspect the two incomplete lines are:
- Length of tails: around 45 meters
- Tail angle from travel direction: about 25 degrees
with "usual formation" meaning V-shaped migratory flock formation.


The fact that the position, direction, speed, and geometry of the flocks birds is provided suggests that these travel vectors be plotted on a graph. Knowing the length and angles of the V-shaped flocks may also indicate that line width is somehow important.

I suspect some sort of meaningful

spatial and temporal pattern may emerge. There will be 7 vertical lines and one horizontal line that will intersect all of them. How much time elapses between flocks passing over each intersection may be relevant.

There are many ways that information could be encoded in this way, but I don't have time to pursue it further right now.

  • $\begingroup$ Yep, that's the rest of the text. I've added the visual tag to the puzzle, maybe that can give you a clue for what to do next. $\endgroup$
    – boboquack
    Commented Apr 18, 2017 at 19:44
  • $\begingroup$ @boboquack Yes, that's why I suggested plotting a graph of the trajectories (and though I didn't state it explicitly, also plotting the shape of the flocks on there as well). $\endgroup$
    – tmpearce
    Commented Apr 18, 2017 at 19:55

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