Wildlife Wednesday: Gift of life – The season of babies
I have decided to go with this title due to the last few weeks I have found the development of babies one of a very fascinating topic. There is so much change that happens over short time periods and at different stages different developments take place. I have therefore looked at the mammal world as it is the season where most babies are born with regards to the seasonal breeders. Season breeders are mammals that have a fairly set time of year at which they give birth and is also linked to the animal’s way of life such as habitat and social behaviour. The seasonal breeders tend to be mostly animals (with the Plains zebra as an exception) that favour the open plains and are usually herd forming antelope. The reason for the seasonal breeders is that it happens from spring to summer where rainfall and food should usually be abundant and with sufficient resources available it puts less stress on the mother during times of lactation. The young develop quickly and therefore have a voracious hunger for milk which is their bulk diet until they are capable of feeding on grasses or leaves.
Impala antelope is a good example as the rams all start rutting early in the year around April to which the strongest and most dominant ram prevails and his prize includes a herd of Impala ewes. Here he will walk with his ladies and mate with as many of them as possible, however, bear in mind that his task is still not over. He has to continuously chase off males who want to mate with the dominant ram’s females. Once mating has taken place the Ewes give birth roughly 6 ½ months later to one young and a few days apart from each other. This creates a nursery system or “creche” to which safety in numbers plays a huge role in the successful rearing of their young.
The all-year-round breeders tend to be animals that favour the more thickly vegetated areas and occur in smaller groups ranging from 2-5 individuals. Here females give birth any time of the year and the reason for this is to avoid having too many numbers with them that will attract too much-unwanted attention. Females tend to remain solitary with their young until they are a bit bigger and then will venture into to open frequently.
A fascinating topic is the size relevance that is related between the mother and her newborn. During my time as a guide, I have been blessed to see many births of a variety of mammals and have always wondered is there a difference with regards to size between each species. Two terminologies which are often used is altricial and precocial which describes the stage of development with a newborn, usually in Birds mostly but can also be used with mammals. Altricial young need more care from their parents and it is clear to understand as they need more time to develop and thus the size between mother and young varies greatly. Humans mother are estimated to be approximately 20 times heavier than their newborn baby while Panda’s also give birth to a newborn that needs the same amount of care however the Panda mother is approximately 900 times heavier than her newborn. The link to infant size whether big or small depends on how self-sufficient the baby needs to be after birth.
The greater the care needed the smaller the baby and the bigger the relative size of the mother while other mammals such as Giraffe the newborn calf could be as big as +- 10% of the mother’s size. Giraffe cows are pregnant for approximately 15 months and then give birth to a calf weighing almost 100 kg and just close to 2 m tall. The birth is done predominantly of the time standing so that the fall over just over a meter snaps the umbilical cord and the slight impact of hitting the ground clears air passages of amniotic fluids. Giraffe calves are born in almost of a superman position with the front legs stretched out and the neck and head laid along the front legs. The ossicones are folded flat while still in the womb but after birth, they quickly stand up and then hard with time.
The young calf can stand after approximately 30 minutes which is reasonably quick for such a large mammal and the capability of running is achieved after 24 hours. However, studies have been done on giraffe brains with the result being very impressive. A newborn giraffe calf’s nervous system is ready at birth with it being almost the equivalent of a 1-year-old human baby, but due to us as humans investing all the important growth in the first year into our brains, wildlife invests all the development in muscle building. This is highly due to the fact of predation on newborn mammals as giraffe have a 50% mortality in the first year. Giraffe calves will almost double their height within the first year as most of the growth takes place at the neck region. After that growth tends to still progress but not as at a rapid state as with the first year. Giraffe youngsters are considered to be an adult at age four with giraffe cows being able to fall pregnant while bulls have to wait a bit longer before they can mate.
- Justin Barlow – Lead Trainer for the Apprentice Field Guide Course
Life is a succession of lessons which must be lived to be understood. All is riddle, and the key to a riddle is another riddle. Ralph Waldo Emerson