Watching these Black Mambas is Just Incredible!


Sep 23 2015

A bit like a sumo wrestling match! This is how Marc Lindsay Rae, head of the specialist safari division at Africa Direct describes this particular video clip of two black mambas. Not certain though if it is a mating ritual or male mambas fighting. Marc explains, 'They are very similar rituals and apparently (I have not seen either one myself) the mating ritual is slightly subdued.'  One can identify the sex of the snake by the length of its tail, but unfortunately in this clip the tails are obstructed by the long grass and secondly they are intertwined.

'Whilst male mambas fight a bit of pushing and shoving occurs and eventually the one with the biggest push wins. The other one will then go off in its own direction. They will never engage in biting,' explains Marc. However there is still a great deal we still don’t know regarding their behaviours. Due to their speed, and the fact that they stay well-hidden it isn’t safe or practical for experts to be in their natural habitat to see what they are doing. We do however chat more to Marc in order to enlighten us regarding a black mamba’s behaviour...

TB: Do black mambas have much interaction with each other?
MLR: Black mambas do not interact with each other besides the mating season. Otherwise, they keep to themselves. Males will typically fight over breeding rights for a female within their territory.

TB: Can you please explain the reproduction process and cycle of black mambas?
MLR: The mating process happens during spring or summer months. This is because they need warm temperatures; therefore the time frame can vary based on location. The males go to the habitat of the females. They may have to fight each other along the way so their level of aggression and tension will increase during this period of time.

The females are very selective about mates but it isn’t’ understood why she will turn some males away. Others though are welcome to stay for a short period of time and to mate with her. Once mating is done though she wants no part of being around him. She will become extremely aggressive if he doesn’t leave.

She may have 10 – 25 eggs created in her body with gestation occurring over approximately 80 to 90 days. She will release them into an area of vegetation that is warm as the eggs need heat to complete the process of incubation. They have to be able to care for themselves as she will disappear as soon as she is done with the eggs. There are only a handful of the young that will reach the age of maturity.

There is little information available concerning the lifespan of wild black mambas, but the longest surviving captive example had a recorded lifespan of 11 years. It is possible that wild snakes may live significantly longer than this.

TB: You mention above that once hatched they are independent. Can you tell us more about the life of a juvenile please?
MLR: Yes, they do not try to raise their young. When the female lays her eggs, she will put them in a safe place and leave them. The babies have to defend for themselves from birth. Following incubation, juvenile mambas break though the egg shell with an egg tooth and are born with fully developed venom glands. Thus, they are capable of inflicting a potentially lethal bite minutes after birth.
The egg yolk is absorbed into the juvenile snake's body as a source of nourishment that sustains the young snake following birth. The first few days and weeks of life end quickly for most of them. They aren’t fast enough or skilled enough to stay away from predators. Mongoose though is one that is does have to reckon with. They aren’t going to be bullied into running off. They are most likely to find the eggs that have been deposited or feed on the young snakes that haven’t been out of the eggs for long. It is unusual that they will try their luck with a full grown black mamba snake. Cape file snakes are a common predator in some locations. Humans tend to be the biggest problem for these snakes though. Due to them being so deadly people will kill them as well as their eggs. They will destroy what they find in the hopes of reducing the population of this snake in the wild.

TB: I have read conflicting stories re juveniles poison – 1. That they can’t control their poison and will typically inject all if biting prey. 2. That they don’t release as much poison as an adult. Can you dispel this for us?
MLR: This is a hot topic amongst many snake specialists, so I am going to quote David Steen on this one. I apologise for the long insert but it makes a lot of sense.

The legend goes that young snakes have not yet learned how to control the amount of venom they inject. They are therefore more dangerous than adult snakes, which will restrict the amount of venom that accompanies a bite. It’s repeated so often that it’s become a sort of mantra among laypeople and biologists alike.

It seems like a simple enough suggestion, but to examine this topic requires some examination of the assumptions implicit within the framing of the question as well as delving into some hot topics in biology. There are four main assumptions when the question is framed in this manner: 1) snakes are able to control the amount of venom they inject, 2) there is some disadvantage to a snake when it injects all of its venom in every bite (otherwise why not inject all of their venom all of the time?), 3) as a result, a snake will learn of these disadvantages and change its behaviour as it matures, and finally, 4) a full envenomation from a young snake is more dangerous than a partial envenomation from an adult snake.

First things first, can a snake control the amount of venom they inject? This is actually a contentious issue among snake specialists. There are some who believe snakes do indeed control the amount of venom they inject, they are proponents of what is considered the Venom Metering Hypothesis (among scientists, a hypothesis is a preliminary explanation of observed phenomena; these explanations haven’t been rigorously tested. This is a step below a scientific theory, which is a conclusion based on observations and experimentation). Past studies have indicated snakes inject different amounts of venom in different situations, but the trends are sometimes inconsistent.

A recent review of studies on the subject suggested although some researchers have documented trends in venom injection, there isn’t compelling evidence to suggest that it was necessarily controlled via any decision by the snake. They came to this conclusion because the trends didn’t seem to indicate the amount of venom the snakes injected would have any consistent benefit in the wild. And if there was no apparent benefit in the wild, then why snakes would be choosing to exhibit this behaviour?

An alternative hypothesis has been termed the Pressure Balance Hypothesis, which suggests the amount of venom a snake injects is due to a combination of snake anatomy and the properties of the object the snake is biting. This would explain why snakes tended to inject different amounts of venom into different targets with no clear benefit to the serpent.

For the purpose of this discussion, let’s say that snakes can control the amount of venom they inject. The second assumption states there must be some disadvantage to a snake injecting all of its venom when it bites; otherwise, a snake would just inject everything every time. Why not?

This is another interesting question. It may be beneficial for a snake to keep some venom on hand in case its intended prey requires a second dose, or if a first prey item escapes and another quickly appears. Another scenario is that a snake does not want to inject all of their venom into their food just in case they are suddenly confronted by a potential predator of their own. Finally, it takes some time for a snake to produce more venom, and energy that goes into venom production is energy these animals could use for other important tasks, such as growth or reproduction. Consequently, common sense would suggest that there are some disadvantages to a full release of venom at every opportunity. It may be possible to confirm this suggestion via experimentation by testing whether snakes that frequently inject all of their venom experience slower growth, lower reproductive rates, or high mortality. To determine this would require a complex study, one that has not yet been attempted.

The third assumption states that as a snake matures, they learn there are disadvantages to delivering full venom loads during every bite and as a result, they change their behaviour. For learning to occur, there must be positive or negative reinforcement. If we state that a snake may keep venom on hand in case a prey item (or one that appears shortly after the first prey item) requires a second bite, this snake must have experienced a number of incidents where they injected a fraction of the venom they had into a prey item only to have this prey item escape. Over time, they may learn that it’s beneficial to keep some venom for a successful attack later. This may make sense superficially, but one might think that it would be more likely that the snake learns to inject more venom with their first bite and increase the chance of a fatality than saving venom just in case they experience another opportunity to bite their intended food again. A commenter has rightly pointed out that there are a number of other potential scenarios we need to consider as plausible.

If we state that a snake learns to withhold venom from their bites in case a potential predator quickly appears and attempts to eat them, a snake must have learned that it’s somehow beneficial to do so. This snake would have had to experience numerous predation attempts and survive to know the costs associated with their venom injection behaviour. If an “empty” snake were to be eaten by an owl or bobcat, then it would know that it should’ve kept some venom (but it’s too late to do anything about it because it’s dead). For a snake to learn it’s beneficial to keep venom ready, it would have had to survive an attack, and if it survived an attack without any venom left over from a previous feeding attempt, then I guess it didn’t really need that venom anyway. So, by logically extending the third assumption, we find that it’s difficult to envision a scenario that would enable a snake to eventually learn that it’s beneficial to withhold the amount of venom it injects with their bite (check the Comments to read about why this sentence was misleading). Remember, it would likely require that this scenario happen numerous times for a snake to eventually learn the consequences of their behaviour.

It’s possible that there are evolutionary advantages to a snake retaining some venom in case it’s needed in a defence against an attack by a predator. It’s easy to conceive how snakes that tended to have venom on hand would be more likely to survive longer and produce young. If this behaviour had a genetic component, the surviving snakes would pass on the tendency to conserve venom to their offspring. This is not learning however, and the behaviour would be innate (i.e. something they’re born with) or instinctual.

Finally, the fourth assumption states that a bite from a young snake that has no control over the amount of venom it injects is more dangerous than a learned adult. But, there are some big snakes out there, and just a fraction of their total venom capacity could be more than 100% of a young snake’s potential venom output. So, I don’t think this final assumption is always valid.

To summarize, although it’s possible that this legend is true and baby snakes are more dangerous than adults because they haven’t learned to control the amount of venom they inject when they bite, it’s safe to say this is unlikely to be the case. And, there's really no evidence to suggest it's true. Due to the complexities of the original question, I doubt this statement will ever be tackled in a manner that sufficiently addresses all of its assumptions. But until then, try not to get bitten by any venomous snakes, no matter how old they are.

TB: What is the most interesting characteristic you can tell us about a black mamba?
MLR: Contrary to what its name would suggest, black mambas are actually brownish in colour, ranging from olive to greyish tones, with paler bellies. They are named for the coloration of the inside of their mouths, which is a deep, inky black. Similar to cottonmouths, when threatened a mamba will open its mouth to show the black lining as a warning signal.

BIO

Marc Lindsay-Rea

At thirty, Marc Lindsay-Rea, who is from the little town of Empangeni in the Kwa Zulu Natal area of South Africa, already has extensive experience in the African bush. This allows him to be a professional in both tour operating and field guiding divisions.

In addition to the bush Marc also has a massive passion for wildlife photography. He has been placed first and third in two international competitions: Africa Geographic / Canon Field Guides Competition and Wildside Nikon All Africa Competition respectively. Davland Calendars and Art publishers have also purchased some of his images to include in their 2012/2013 calendars of wildlife in action, which is sold internationally.



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