|A Starling fledgling on our bird table|
We also have Blue Tits nesting in a box on our Apple tree, and some Dunnocks nearby too. But the inspiration for today`s post is thanks to a nest of Blackbird eggs that my Dad came across. He was tying back some clematis on an arch when he flushed a Blackbird which was sat on a nest. There are four beautiful blue eggs in it, and Dad very carefully took this photo of them. He then left it well alone and the parents came straight back to it to keep the eggs warm. The clematis will have to grow a bit wilder this year as we don't want to disturb the birds.
|The Blackbird nest that inspired this blog!|
Dad showed the picture to Mum, who then started raising some very interesting questions, many people may already know the answer to these questions but it made me think if Mum wasn't sure about all the details, maybe other people wouldn't be so sure either, therefore the focus for this post is… “What goes on inside the female bird during the egg making process!?”
Well with the help of the internet I discovered the following:
- For birds, their courting process and behaviour takes quite a while and includes many stages. From claiming territory there follows an elaborate courtship including dancing, calls, spectacular flights (love watching Lapwings do this) and plumage, it is all so that the male can demonstrate to the female how healthy and strong he is, which means that his chicks will be healthy and have the best chance of survival.
- Some birds mate for life like the Gannet, often travelling unbelievably long journeys to meet up again, while others find a new mate each year, like the Blackbird
- Birds don't have the usual type of reproduction organs that we are most familiar with. Instead they both have Cloaca which are little openings. Through this they do everything, including urination, defecation and mating.
- During the breeding season, the Cloaca of both male and female birds swells and protrudes slightly, and the male`s Cloaca holds their sperm until such a time as they are able to mate, when it is then deposited into the female and travels to meet the female's egg which is stored in her ovaries.
|A Blackbird fledgling on the bird table |
- this one is feeding itself now
- If you see a pair of birds mating, keep your distance because if you distract them and interrupt proceedings, it can harm their bond with each other. It is a very brief interaction where the male balances on the female, and then it is over.
- Out of all the 9000 species of birds, all of them lay eggs rather than producing a live off-spring. This is believed to be due to the fact that as birds have such fantastic mobility and agility, they need to maintain their ultra-light anatomy so carrying around a clutch of chicks inside them in the same way a dog carries a litter of puppies inside her, just wouldn't be possible.
- Female birds carry one single egg at a time and due to its weight impacting on her ability to fly, as soon as it is viable (ready to be laid) it is. A Blackbird for example generally lays 3 or 4 eggs per clutch, laying one egg per day. Each egg has a protective shell around it which has already hardened to keep the precious chick safe. While we think that eggs are extremely fragile they are actually designed to withstand a huge amount of force, to be able to withstand the parent sitting on it whilst incubating it for example. Eggs are oval and so the same engineering principals of an arched-bridge apply, the convex surface can withstand much more pressure than other shapes. The shells need to be robust because many, many predators would just love to get their beaks, paws or claws onto the protein-rich contents of the egg.
|Two starling fledglings waiting to be fed - they're not |
feeding themselves yet - there's fat balls in the
window box they are perched on!
- One of the vital components of raising healthy chicks to fledgling status is the location and stability of the nest. This is the task of the male bird and again is to demonstrate to the female his suitability. A European House Wren is said to build up to 12 nests in varying locations until a female grants her approval and chooses him as her mate. The nest must be well constructed and inconspicuous. Birds have varying techniques for building the perfect nest and some will line them with moss, lichen, leaves and feathers for warmth and comfort, others will produce a sticky substance to help the eggs to stay in place. Some breeds of bird will stay with the eggs throughout the entire incubation period, a Hornbill for example will seal herself into the nest with only a small hole enabling her mate to feed her through.
- Incubation can take between 13-14 days and then comes a frantic period of feeding the brood, often an ordeal in itself with much success depending on the weather, accessibility to the right insects, etc. If enough food is brought to the chicks, fledging then takes place, usually about a fortnight later, though this can vary with species, for example the longest incubation period for any bird is 64-67 days with the Emperor Penguin!
Hope you enjoyed,