Naja mossambica odd behaviour?

[Jen]

Hi there
We have had two N mossambica bites admitted to the same Durban hospital. Both patients were asleep on the ground in their huts when they were bitten. Both came from the Nongoma region of Northern KZN. The first was a 10 year old child, bitten on the shoulder & the second was an adult bitten on the neck. No 'spitting' of venom was involved - the snakes were unprovoked. Neither bite has been particularly serious - swelling & local effects, but no systemic effects & neither required anti-venom. This probably means that the venom dose wasn't particularly high. My question is - is this a usual pattern for Mfezis? I do know that some snakes, particularly kraits, will bite people when they are sleeping as they try to get close to them for warmth. It has been incredibly hot in KZN lately so I doubt that this is the reason... I'm just a bit perplexed!
Any ideas?

[Graeme]

I have heard of people and livestock being spat at from rock crevices with no apparent provocation.
Perhaps some specimens, just have a really nasty/overly nervous disposition. One scenario that comes to mind is where the snakes in question are exploring the exposed (head and shoulders) areas of the sleeping people, and possibly being slapped away as the flicking tongue gets mistaken for an insect. But then one would suppose, there would be at least the same number of victims with bites on their hands.
Very interesting Jen. Hopefully somebody can get to the bottom of this mystery and preventive measures can be applied where neccessary.

[vuduman]

Very interesting Jen.I have caught many Naja mossambica,and in different settings:Day,night,lifting things and descovering them,crossing roads at night,caught them basking in the sun and removed out of roofs with a flashlight.I have noticed that most of them reacts directly to their sircumstance when captured.

Only two of them has ever spat at me at night time or in complete darkness(and they didn't get it on my glasses either).I think they are alot calmer at night or maybe its because they can not see the eyes of the prevoker, that they sease to spit.At night all they want to do is get away silently and only stand their ground and hood when cornered.But a bite is always a last resort,so maybe they got rolled onto by the sleeping victim in both cases.

[rolandslf]

Very interesting post Jen. This raises the question which I seem to recall from somewhere, sometime back.

The question was whether snakes release larger quantities of venom when they know that a kill is needed for a prey item, or otherwise go hungry. "OR" Whether smaller quantities of venom are released when a defensive bite is needed.

The fact that these victims needed no or nearly no Anti-Venom would suggest that possibly, less venom is released for defensive bites.

Thanks for the thread.

[WW]

Bite to people asleep on the floor of huts is very typical of spitting cobras across Africa! In terms of how people get bitten, they occupy a similar "niche" to kraits.

Re defensive vs. feeding bites, cobras have not been studied in detail, but rattlesnakes at least actually release on average MORE venom in a defensive bite than a feeding bite; however, the variance is also much greater in defensive bites, which of course corresponds to what we observe: some bitten people have minimal symptoms, others have massive envenoming. In feeding bites, on the other hand, rattlesnakes at least seem to dose the venom according to prey size, and variance is low.

It makes sense to a substantial extent. If you are going hunting, you will choose a different gun if you are hunting partridge than if you are hunting elephants. On the other hand, if you are suddenly attacked by something much bigger than you, then chances are you will grab the first thing that's handy. One day it might be an air rifle, the next it might be an RPG launcher.

[wildfrontier]

Hi Jen, interesting post.
I have had much experience catching these guys where we used to live in Mpumalanga. I was always perplexed as to why they entered human dwellings. In my situation, the main diet of the Mfezi's was frogs, and people who had ponds or waterholes for the animals close to their homes had my number on speed dial, as they were constantly having these guys enter their homes. One particular incident which resulted in a bite involved a teenage girl who was bitten on her back when she climbed into bed and did not see the snake under the covers. The bite did not seem to have sufficient venom to be life threatening, but as far as I am aware she did receive some antivenom to counteract the tissue destruction. I saw her a week or so later and she had a golf ball sized hole in her back as a result of the bite
What prompted the snake to seek out this location??
The only conclusion I can draw is that the snakes entered the homes for temperature control purposes, not for feeding, cos their favourite food was outside.
Most of the homes were thatch, and as such had quite a temperature difference compared to the outside temperature. Remember that the snakes don't always seek out heat, but may be entering the homes to seek a cooler location to escape the heat outside. They may be encountering the humans as the snakes are exiting the dwelling to begin their evening hunting.

[Rodis]

Hi Guys

This is the only species that I feel I might be qualified to comment on.

This is by far the most dominant species caught in the Pilansberg and the surrounding lodges, including Sun City.
Whenever we have a call out, we just grab a hook stick and glasses and know what to expect. On our lodge we have a record of catching 11 separate animals in one day; however I must add that this year has been very quite in comparison to last year. I am not sure if the amount of rain that we have had, has anything to do with it.

My experience with this species is that it is a very nervous and shy cobra, in this area at least. They hardly try to stand their ground.

They "spit and move". They spit at anything and everything, but as they spit, they try to escape. They will spit from anywhere without being provoked. I once watched a fairly sized adult hide under a rock while I was waiting for a hook stick and glasses. Every movement I made was being watched and as soon as I moved I got a jet of venom. This guy was so big that I could actually watch the stream of venom come at me and then side step it. In my experience they do not like to bite, in this area at least (I have spoken to others who do not agree with me) they never attach a hook stick, they never strike, they just spit and move. This my personal experience.

Their characters do not vary much in my experience, like with all animals the juveniles are a lot more nervous and are mostly caught in the day. When caught at twilight they seem to be very calm. Two weeks ago I caught a small juvenile at about 7 in the evening. He did not spit, hood, nothing. However when used in a demo, he was a typical Mfezi, perhaps even more so.

We remove these from our units on a frequent basis; I check my shoes and my bed every time I get into them. This is my worse nightmare as I have a two year old that loves reptiles and does not have any fear of snakes. So I have tried drilling my stupid mantra into his head. (Daddies snakes good- Outside bad). It’s stupid I know and any advice here will be welcomed, however I do not want to instil fear of reptiles into him.

Besides coming in to cool down, I think they follow their food sources, for instance red toads are find in these units all the time.
I remove on average 3-4 of them a night from my unit.
To put it into perspective, I did my handling course in July last year with Mike Perry, since then I have been doing catching and releasing and if I look at the stats I have sent to Natcon, I have removed 16 spitters(majority under 1m), one house snake and assisted with one black mamba.
That my species list so far. In fact its starting it gets irritating as I would like the experience of catching other species.

WW- Thank you for your post, its dam interesting and to me it proves that snakes are intelligent animals and not purely driven by instinct. In my opinion which I do not rate very highly, it also proves that snakes learn from their experiences.