The Nachtkrapp is a german version of the bogeyman or in a more general term a kind of bugbear. Nacht is the german word for night and Krapp is used in southern germany and austria as a word for raven. There are many different versions of this tale. Most of the time it was used to make children go to bed by stating that the night raven will abduct them when they are outside past their bedtime.

But I am especially interested in a norse version of the night raven, for which I am trying to think of ways to explain how they could evolve naturally:

  • the night raven is hunting for prey at night
  • it doesn't have eyes and if one were to look at the empty eye-sockets he would die
  • it has holes in its wings that cause illness and disease when someone looks at them
  • the prey can be up to the size of a little human child which it will be, according to the Wikipedia article,

    messily devour [...], first ripping off their limbs and then picking out their heart

According to the german wikipedia article Krapp can also be used as a general term for birds belonging to the raven family, or Corvidae, but it might also just refer to the raven black color, similar to the word Rappe, which is a black horse. The night raven might also refer to other birds, such as owls or night herons.

I was trying to think of ways to realistically create such a creature in my world. The criteria are listed above and I am trying to come as close to it as possible. This means that for example the part about messily devouring children and ripping off their limbs can safely be ignored for normal sized ravens or owls. The legend sometimes states that the raven is indeed a giant raven, but I want to avoid discussions about the Square-Cube-Law, so we will go without something roughly the size of a normal raven.

I was thinking about basing it off the Medusa and going with a similar approach to this great answer, but in the case of the Medusa answer the hair is spitting a venom at the prey, which leads to a slow death instead of looking in the eyes of the creature. Turning into stone also doesn't seem to fit the traditional idea of a general harbinger of death and disease. To make sure that this question is not viewed as a duplicate to the linked question I will postulate the following that I am trying to achieve in addition to the criteria listed above:

  • the death cannot be based on turning the prey to stone
  • the creature cannot have other creatures in place of the holes and empty eye-sockets that would assist in killing the prey
  • looking into the eye-sockets should be deadly for the prey
  • looking at the holes in the wings should only cause an illness or disease; nothing necessarily deadly

How close can I realistically get to my harbinger of death, the Nachtkrapp?

A list of all the questions from the series Anatomically Correct can be found here.

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    $\begingroup$ Holy Krapp! And other corvidae cries of confusion! An anatomically version of a supernatural harbinger of death. This a challenge and a half. I was thinking of this would be a near-impossibility and giving it a swerve, but my brain cells started tingling. Mmm! Interesting! $\endgroup$
    – a4android
    Commented Aug 7, 2017 at 8:31
  • $\begingroup$ @a4android It is indeed a challenge worthy of the great minds of WorldBuilding, which is why I come to you to seek assistance in creating my real-life harbinger of death! $\endgroup$
    – Secespitus
    Commented Aug 7, 2017 at 8:37
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    $\begingroup$ Sadly the great minds of Worldbuilding SE are having the day off, but I have on good authority that one of its lesser intellects has foolishly posted a possible model for your real-life [sic] harbinger of death. However, fear not, the great minds will soon show up and have a field day. $\endgroup$
    – a4android
    Commented Aug 7, 2017 at 9:06

2 Answers 2


Like the majority of harbingers of death, the dreaded Nachtkrapp doesn't foretell or supernaturally portend a death. Most especially when it is disease or death caused by plague or illness. The nachtkrapp could have supersenstive senses that enable it to detect those who are afflicted by illness or plague, but who have yet to express the symptoms of their disease. The fact that persons who see the nachtkrapp and succumb to illness this will be naturally enough interpreted as being caused by the bogeyman bird when, in fact, it's not. Errors in causation are often responsible for imputations of supernatural agency when none exists.

The querent has established that the nachtkrapp is a giant creature. This explains its ability to rend the limbs of children and take them as prey.

Anyone familiar with biology would be concerned about a giant bird can get about at night with empty eye-sockets. The answer is simplicity itself. The apparent eye-sockets are sources of powerful ultrasound. This obviates the need for eyes of the conventional kind. What might pass for eyes in any other species of bird is replaced by membranes capable of generating high-intensity ultrasound. These would be part of the nachtkrapp's nasal passages, powered by powerful blasts of air, which a giant bird should be capable thereof, and not ocular cavities where eyes would be located.

It is by looking into the sightless eye-sockets of nachtkrapp and being exposed to its intense and lethal ultrasonic "gaze" that brings death. While medical ultrasonic scanning and sonotherapy is regarded as safe, there are some potential deleterious effects.

One of the most well known effects of ultrasound is that as Ultrasound waves pass through a tissue they tend to heat it up. The tissue can easily be warmed to 40 degrees Celsius. Although in vivo the heat is usually easily carried away by blood circulation or simply dissipated into surrounding tissues. this regiment can be applied in a technique called Ultrasound therapy where this heat is used to stimulate repair to damaged internal tissues. Another well known effect of Ultrasound are cavitations. Cavitations are small bubbles of gas that are released upon exposure to extreme negative pressure. These bubbles can cause cells or even tissues to rupture.

Source: Effects of ultrasound

In the case of the nachtkrapp it can be assumed its high-intensity ultrasonic 'beams" will be powerful enough to cause deadly harm to those who are unfortunate enough to see this fatal fowl, sorry, dread harbinger of death who flies by night and preys upon little ones who don't go to bed early.

  • $\begingroup$ @Secespitus Appreciate the edit. Well spotted! $\endgroup$
    – a4android
    Commented Aug 7, 2017 at 9:36
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    $\begingroup$ I really like death by cavitation. It even takes care of question how they hunt - cause brain trauma and hemorrhaging and wait for prey to succumb after short while. That way they could potentially slay prey much, much larger than bird itself. $\endgroup$
    – M i ech
    Commented Aug 7, 2017 at 14:06
  • $\begingroup$ How much energy would be needed to heat up tissue in small mammals to a degree that would kill or stun the prey? I believe it would be rather much. If the Nachtkrapp is hunting with ultrasound similar to some bat species, it'd be likely that it also evolved large ears to better detect reflected sound. Bird-like ears won't do the trick here. $\endgroup$
    – Orphevs
    Commented Apr 2, 2018 at 23:42

You could have your bird (which I envision as a large owl) possess the evil eye. The wings could have coloration around the holes like eyespots, which can be seen on the wings of some birds. These are lesser evil eyes.

Owl with wings spread out From https://i.sstatic.net/CNO7a.jpg

The evil eye is definitely bad and feared. People worry about it and wear charms against it - to this day. But it is not mechanistic. The ancient Greek philosphers were in no doubt that it was real but they could not explain how it worked. There is a huge body of folklore, from many different countries and you can borrow, mix or match.

How does a bird with no eye have the evil eye? Maybe it does have an eye but it does not always show. It comes out when the bird wants to use it.

I think it is creepier to leave up in the air how exactly the evil eye works. From a storytelling standpoint, if a person sees a bird at night and drops dead, further literary endeavors from that persons point of view will be limited. A person who sees the evil eye and lives - for the time being - still has agency and a viewpoint and can help make an interesting story.


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