(Corner Nest)
Egg drop on floor is common. Don’t be surprised when you find eggs on your Bh' floor. It is a natural occurrence. It is common to see 10%-20% of eggs dropped from nests in all Bhs. The main causes include accidental ejection by the adult (cause by panic), narrow and shallow nests, etc.
Incubating Swiftlets normally sit facing the planks or wall with tail and wings projected over the edge of the nest. When there is predator or there is a shock that create panic they leap off the nest to make a sideway turn. The powerful flip of the wings create strong lift, this is where the eggs are tossed out from the nest. The egg is incubated between the adult legs. The panic flight which cause the egg caught between the feet, a sudden powerful lift and turn sideways would easily toss eggs out from the nests.
Shallow and small nest has higher chances of loosing egg compared to a deeper rounded nest. From here we could clearly understand why birds prefer to make nest at 90dg corner of the plank.
Corner nest is deeper, because of its deepness it is rare to have egg tossed out. You can check and observe it yourself. Therefore many old timers (old sifu) discourage the use of corner board. They knew this would help to increase the population fast especially for new Bh but they didn’t know the reason behind it. It needs observation and research to discover this.
What causes the panic flight? Predators such as Owl, Rats, Geckos and without forgetting the way we enter the Bh(ourselves to be blamed) caused the panic flight.
If you find many eggs on the floor of the Bh more than normal you should check and find out, it could be predators. They could have entered the Bh. Check for sign of predators.
Secondly the ways we enter the Bh, I am sure different people or Sifu have different ways of doing things. Some say switch off the sound completely, some say it is OK to switch on the light, some say don’t switch off the sound and so on. So who is right and who is wrong? Well it is up to you to decide who you want to follow.
As for me I stick to common sense and what nature and the birds wanted. In order not to create a shock which mean a sudden appearance in a dark environment I would first stop the external sound. (I wouldn’t want to attract birds to fly into the Bh while I am inside). After 15 minute I reduce the volume of internal sound to 10% (minus 90%). This is to inform those birds and chicks inside there are still many friends flying around. I wait for another 15 minute then I would enter the Bh with a flash light. I prefer using warm light to reduce young birds in the Bh flying towards the flash light (White day light attract more birds). After moving around the Bh for a while by this time most of the birds would have fly out from the Bh then I would switch on the florescent lights in the Bh to do my work.
I discovered by this way it would reduce panic among birds. Of course some would do harvesting or repair works in Bh entirely relied on head light and flash light. Most importantly whatever ways you prefer make sure you don’t make the birds panic especially those that are sitting on the eggs.
The above answer the question asked by Mr. K from Bkt. Mertajam. (“James, why I found eggs on my Bh’s floor?)
Good Swiftlet Farming All!