I do intend to carry out a pilot test on the efficiency of barn owl Tyto alba to reduce rodent infestation in urban affected tropical zones. I would like to know the most challenging factors faced by anyone who ever had done such project. Give advice and share the results, please. Many thanks.
Nest boxes for Tyto are used in many areas of north america. Some places may place owl next boxes for the specific purpose of trying to reduce rodent populations. There should be many papers published on Tyto diet so you could learn if they prey on rats. The Birds of North America web site has excellent summarized information on Tyto alba.
Thanks a lot, Arvind Singh, Surender Singh and Christopher W. Swarth for the contribution.
Any specific species more suitable for tropical zones like South East Asia or the Carribean zones in comparison to those species existing in a temperate climate habitat?
You ask about "challenging factors" I would also suggest you consider carefully what other control efforts are being undertaken and how they may interact with barn owls. For example: given that it is an urban area, is there significant use of poisons such as anti-coagulant rodenticides taking place?
There are a large number of published studies on the bio-accumulation of rodenticide residues in barn owls (from birds eating rodents that have themselves eaten poisons), depending on the situation this could be a potential problem for a study if there is heavy poison use in a location where you are trying to establish a barn owl population (perhaps it could be one reason among many why there aren't many barn owls there already?).
Steve Campbell thanks. I strongly agree with your point and if there is a relation (cause-effect) between the poor natural presence of barn owl in urban cities of tropical countries with rodenticides usage is yet to be investigated.
The size of Tyto alba does not allow her to depredate on large prey and this fact also may be a problem for.control of rats in urban áreas.
Extracting from the paper:: Morris, P. (1979). Rats in the diet of the barn owl (Tyto alba). Journal of zoology, 189(4), 540-545.
"There is clear evidence of size selectivity by the owls, probably because a full grown rat would prove a formidable adversary for a bird which weighs only about 300 g. Ninety one per cent of the predated rats had predicted body weights of less than 100 g, compared with about 12 % in a sample of dead Brown rats collected after poison trials by Bishop & Hartley (1976). Only about one quarter of their wild population comprised animals which were within the size range evidently taken by Barn owls".
Thanks, Alfonso Balmori, an interesting practical point for efficiency control.
Do we conclude from one study that all Tyto alba species are limited on the same basis? Aren't there other species bigger in size and more powerful? It would be necessary to confirm this with additional field trial. From the referred study, it was a predicted body weight of less than 100 g.
Does that study permit to conclude that the barn owl never eliminates a bigger rat, with such powerful claws? I mean by breaking the neck zone close to the head, any rat become totally neutralised. The barn owl is a stealth type of predator: no rats - young or adult are able to detect the owl's approaching to snatch and clamp their neck spine bone.
Even though the predator has no ability to bring back its prey to the nest, I wonder if we could have occurrences of such cases too. Is there any possibility?
I am curious to know if someone could confirm or deny my hypothesis?
Or else it means that the barn owl can detect from a large distance that such and such size of rats is within the only possible range of catching ability in order to be taken back to the nest without any hindrance. It implies or suggests that a selection of the size of targeted rodent is done by the animal with precision: the barn owl really choose the rodent size < 100 g?
So on the contrary, if Tyto alba systematically randomly attack any rats in their sight,
they might be able to still eliminate the animal pest leaving it on site to further look for a smaller rodent?
Barn owls hunt in open landscapes and therefore will not be able to control rodents in urban areas. Even if a barn owl will breed in an urban area, I would suspect that they will hunt in neighboring fields and not inside the urban area itself. Unlike in open landscapes, where barn owls can breed in very high densities, in urban areas owl populations will always be lower. Many "conservation" type NGO's will always try to push this idea because it sells and catches the medias eye. Typically these projects are short lived and without results. I would stick with you projects in the Palms and rice fields. Good luck!
Good day Motti Charter,
Well said "Many conservation type NGO's" -"it sells and catches the media's eye".
Some pilot projects are being carried out by NGO's in collaboration with research university: the interest is also practical for more student field work exposure and final year student project writing.
It would be interesting to provide me with some data on your comments, thanks.
What is the average maximum distance the barn owls could cover for hunting?
And yes my work on plant protection (IPM), applied ecology-entomology, is my priority.
Thanks for your input.
Pierre (Island of Martinique)
Hi Pierre. Barn owls frequently prey on several different species of rodents including some species not frequently sampled by traditional trapping methods. In this sense, if you want to publicize your results with the local people living in the area keep in mind that the perception of the population size of rodents by the general public (based on sightings or captures for instance) could be different from the "real" composition and population size of rodents in the area.
Please see
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1676-06032015000200109
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1984-46702011000600003
Also, since barn owls hunt in open areas (as Motti Charter nicely tells above) they could be susceptible to be killed by cars in roads. This is unfortunately frequent in my region here in Brazil. Have this is mind when you will think about the placement location of the nest boxes.
All the best!
Alexander
Good day Alexander V. Christianini
Interesting comments. Noted, thanks.
Regards,
Pierre (Island of Martinique)
More 75 % of diet in Tyto furcata and Tyto alba in all distribution are rodents
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