Tag Archives: Egyptian

Weird birds

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Egyptian vultures exhibit strange mud-coloring rituals.

Egyptian vultures exhibit strange mud-coloring rituals.{credit}Manuel de la Riva{/credit}

Scientists have discovered that Egyptian vultures engage in a peculiar “mudding” ritual that is one among a set of unique behaviors that not only distinguish the vultures from other birds of prey, but also, quite frankly, make them look a little “weird” in comparison.

In a new research paper in the journal Ecology, scientists Thijs van Overveld, Manuel de la Riva and José Antonio Donázar of the Estación Biológica de Doñana, Sevilla, Spain, describe the coloring ritual in detail, opining that the behaviour, where the birds dip their heads, necks and even chest in red soil, essentially bathing their upper bodies in mud, might represent a complex communication technique through which the birds relay social information.

Nature Middle East chats with Overveld about the intriguing mud bathing ritual, and what it tells us about the North African birds.

NME: What does knowing about this coloring ritual add to the body of knowledge we have about the bird?

Overveld: The situation of Egyptian vulture is not very good, and currently classified as critically endangered, so few birds are left and we actually know very little about their behaviour. What we do know is that the Egyptian vultures are among the most peculiar birds worldwide. The vulture has a unique behavioural reportoire, such as stone throwing to open eggs; it also eats excrement of ungulates which turns their face into yellow.

Our work adds a new, and unusual behaviour to their behavioural reportoire, which so far has only been described in its close relative, the Bearded vulture.

NME: What are some of the observations that you have made about the birds?

Overveld: These birds have a far more complex social life than previously assumed. Since these birds are non-vocal, we don’t rule out that mud bathing may be used to signal certain social information.

The most intriguing part of the painting behavior is the amount of individual variation.

I have been repeating the experiments in the last week, and the interest in the mud (and disinterest) is striking. We are just at the beginning of our work, so it is difficult to give a clear answer. We can rule out some options like social status, for instance; sanitary benefits also seem unlikely because some birds don’t use mud when it’s in front of them, but we cannot give an answer to why they do it.

NME: Is it as strange as it sounds? Is it atypical in any way?

Overveld: The bird is clearly a special case among birds generally, but most interesting, it’s a vulture that is general regarded as a filthy animal. This has been quite different in the past, given that many societies treat them as sacred animals. As you know, they have been providing essential ecosystem services by eating dead animals and thereby avoiding the spread of diseases.

The significance of our work is two-fold, we decsribe a behaviour that may tell us more about how [the birds] live and their adaptations, while meanwhile, we show that a highly threatened bird – with remarkable behaviors unique among birds worldwide – is disappearing.

NME: How does the coloring happen? What do the birds do exactly?

Overveld: When birds notice red mud, something happens. Some birds can stare or gaze at the mud for 20 minutes, only to scratch the mud and leave. Others step in the bowl and start to scratch, look at it very carefully and then typically swipe both sides of the head and neck in the mud.

The most important thing of our experiment is that we show birds get dirty on purpose. Some start with a bath in clear water and then go all the way in red mud.

The questions is why do some birds want to become so dirty, and why is it as if some birds look [like they’re about] to take the most important decision in their life before swiping their head [in the mud].

Currently we are describing in more detail the behaviour during different parts of the year in combination with experimental work to figure out whether they may signal other social cues we yet don’t know. They have a more social complex life than previously acknowledged so we currently don’t rule out any option.

The world finally has recorded the strange mud bathing rituals of the Egyptian vultures.

Scientists have finally recorded the strange mud bathing rituals of Egyptian vultures.{credit}Thijs van Overveld{/credit}

If you’re curious about how Egyptian vultures bathe in mud, and would like to see the ritual in action, check out the following videos, courtesy of Overveld and colleagues: Video 1, Video 2, Video 3. According to the researchers, the videos are the first ever recordings of this specific mudding behavior.

Decoding bat talk

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The Egyptian fruit bat is a highly social mammal roosting in crowded colonies.

The Egyptian fruit bat is a highly social mammal roosting in crowded colonies.{credit}Michal Samuni-Blank{/credit}

Bats are extremely social mammals, that live in colonies of thousands and sometimes millions, and they talk or “sing” to each other to communicate. Now, a group of scientists have studied vocalizations by Egyptian fruit bats and they found out that the calls contain information such as the identity of the caller as well as the context of the call.

The study published in Scientific Reports carries an analysis of almost 15,000 vocalizations of 22 Egyptian fruit bats, recorded over 75 days. The analysis paints a picture of some of the social interactions that the animals engage in.

“Bats spend many, up to 40 years, together with the same individuals around them and they live in the dark. All of these suggest that a sophisticated vocal communication might evolve in such animals and this is what we set to examine,” says Yossi Yovel of Tel Aviv University, corresponding author of the study.

The vocalizations the scientists recorded represented the full vocal repertoire the bats used during the experiment. And it turns out the cacophony of sounds that a person hears entering a bat cave is far from just noise, according to Yovel.

Although the calls sounds alike and were previously categorized under one category that boils down to “bat shouting”, the scientists showed it’s not the case.

“The vocalizations we looked at in this study were all categorized in the past as agonistic calls, that is, aggressive vocalizations emitted during fighting,” says Yovel. “We now show that there is information in this chaos. We demonstrate that a third individual listening to a fight between two bats can tell who is shouting, what is the context of shouting, for example fighting over food or over position or over mating, and even to some extent who is being shouted at.”

That said, the communication of the Egyptian bats described therein doesn’t include clearly distinct words, as human communication for instance does, or what linguists often call semantics. “We do not find a ‘word’ that mean ‘hello’ or ‘move’ or ‘eat’ in bat communication. We just show that the spectral content of the vocalizations or their frequencies contain information about the context.”

The scientists elaborates: “You could imagine this as something like this: when a bat shouts at another bat for taking its food, the vocalizations will always be higher in pitch than when they are fighting over a position in the cave. This is what this cannot be defined as language and yet, because we will probably never fully understand animal communication it is important to understand its complexity.”

The next step, which the scientists have already taken, is into learning whether or not these vocalizations are learned by the bats or whether they are born with their vocal repertoire. “Learning new vocalizations is a main factor characterizing human language and it is debated how much other mammals depend on learning to develop their communication,” comments Yovel.