(look at the white Styrofoam chips stick to the nests. Nest harvest from 11 months Bh))
You need to harvest all nests that left by the young birds. Swiftlets in a way like to recycle their nests. Once the chicks had fled the nests have to be harvested otherwise other birds that are into mating or the same pair that had used the nests before would use it back. In this way the owner may miss a cycle of harvesting. So the actual number of nests could have been higher but the owner didn’t take the advantage.
Many farmers especially those from new bhs rarely harvest their nests. Some keeping them till a year or more. Sighted it is better this way as they afraid if they harvest them they might not see those nests again. This is absolutely wrong. As long the young birds have left the nests it can be harvested. It is nature’s condition, good harvesting could push up the number of nests but it has to be done in a good and well planned manner.
Understand the cycle and period of breeding, the high and low of number of nests throughout the 12 months period of a particular Bh or area would help in planning out the harvesting schedule. Jot them down every time you visit your Bh, the number of nests, nests markings, etc. Make a chart from here a high and low month of brooding could be seen. From here you would know how many times you need to harvest per year. Note, this is particular vital for Bh that has reached 1 year and above. Any wrong or improper planning of harvesting during the essential growth period would push down the number nests.
Sometimes it is good to follow the books. There are lots of books from Indonesia which write about the period of breeding season, harvesting, etc. You may learn few things from there but don’t forget the geographical area of Indonesia is not the same as Malaysia. Their breeding and brooding period is not the same as well because most of these periods are coincide with raining and monsoon season. What is raining season in Indonesia but for Malaysia it could be hot weather due to its geographical location.
Let’s not look too far for comparison, even within the East and West of Malaysia there is significant differences in term of peak and low season. The raining season influences the breeding time as most nests building started before or early of the raining season. So this 2 seasons influence the harvesting schedule.
As for new Bhs that have got not many nests it is good to harvest them as this would prevent the nests from being recycled again.
Second it is a must to remove (harvests) those Styrofoam fake nests that have been left by birds. If not they would continue to build nest on those same fake nests and the white chips of the Styrofoam would stick and pollute the nests.
Also not to forget if possible never harvest the nests during rainy day. It not good for your Bh.
Good Swiftlet Farming All.