Need to control rodents on your crops? Use birds of prey!

The great horned owl is one bird of prey that can be used to control rodents on farmland © Abigail Rumsey

The Society for the Protection of Nature in Israel is encouraging farmers to use barn owls (Tyto alba) to control rodent pests on their crops. They aim to attract barn owls by constructing nest boxes; so far 2,000 have been distributed to farmers. As barn owls only hunt at night, day-hunting kestrels are also being provided for to ensure a more effective rodent-targetting system. Although it has taken a while to persuade farmers in neighbouring Jordan to take up the use of barn owls in their fields, success has also been had controlling rodent populations there.

It isn’t just farmers from the Middle East that have found birds of prey to be beneficial when dealing with rodent pests. All around the world, farmers have found that this natural solution can be cheaper and less harmful to the environment than using poisons or traps. Here are some case studies of using birds of prey in agriculture:

Indonesia

Indonesia produces about 20 million metric tons of palm oil a year. Where rats are a problem around oil palms, they can lead to losses of around 5% yield. In South Sumatra, oil palm growers have been rearing barn owls to control the rat population. One company, BW Plantation, has found that this method of control can be 50% cheaper than using chemicals, and they now save $300,000 a year because they don’t have to buy poisons.

Hungary

When farms were smaller, pesky voles would be caught by cats, killed by farmers, or hunted by buzzards and harriers that would sit in the trees. These days, there are no longer any trees for the birds of prey to perch on. One farmer in Karcag, Hungary whose crops were being damaged by voles found a simple solution to his problem.  He installed his own wooden perches around the edges of his fields to encourage the birds of prey to hunt there. This way, he managed to eradicate 90% of the voles within a few weeks with the help of the birds.

India

Researchers in Maharashtra State in India found that the Indian eagle owl (Bubo bengalensis) had potential as a predator of agricultural pests. They found that the owls preferred to nest around agricultural land, and that almost 90% of the prey that they consumed were agricultural pests, particularly rodents. This study has shown that Indian eagle owls are a suitable bird of prey to recruit for agricultural pest management, and will encourage farmers to protect this uncommon species.

USA

The great horned owl (Bubo virginianus) is the largest nocturnal raptor in the United States. They inhabit many different landscapes and have a diverse diet. They are particularly adept at controlling larger rodents and rabbits on farmland, and are the only animals known to eat skunks, which can cause crop damage.

New Zealand

It isn’t only rodents that can be controlled by birds of prey. It was found in New Zealand that introduction of the threatened New Zealand falcon (Falco novaeseelandiae) to vineyards helped to drastically reduce the amount of damage to grapes by non-native passerine birds.

Using birds of prey isn’t always a perfect solution, particularly if farmers don’t commit entirely to using this method. When barn owl nesting boxes were initially trialled in the Hula Valley in Israel in the 1980s, it wasn’t long before farmers started using rodenticides again, which killed the barn owls. However, many other recent projects have shown that integrating birds of prey into the agricultural ecosystem is a cost effective and environmentally friendly way of controlling non-insect pests. In addition to this, it can aid in protecting the birds of prey themselves. Indian eagle owls are still hunted due to superstitious beliefs so promotion of their benefit to agriculture could aid their conservation. And, as with the relocation of New Zealand falcons to vineyards, it could help boost population numbers of threatened species.

Cheaper, environmentally friendly pest control © Abigail Rumsey

Sources:

Charter, M. (n.d.) Using Barn Owls (Tyto alba erlangeri) For Biological Pest Control In Israel. World Owl Trust. Available from: http://www.owls.org/Conservation/pest_control.htm

GrrlScientist (2012) Birds of prey as ambassadors of peace in the Middle East. The Guardian. Available from: http://www.guardian.co.uk/science/grrlscientist/2012/feb/09/1

Kross, S.M., Tylianakis, J.M. & Nelson, X.J. (2012) Effects of Introducing Threatened Falcons into Vineyards on Abundance of Passeriformes and Bird Damage to Grapes. Conservation Biology 26: 142–149. doi: 10.1111/j.1523-1739.2011.01756.x

Pande, S. & Dahanukar, N. (2011) The diet of Indian Eagle Owl Bubo bengalensis and its agronomic significance. Journal of Threatened Taxa 3 (8): 2011–2017. Available from: http://www.threatenedtaxa.org/ZooPrintJournal/2011/August/neelesh.htm

Press Office of the Ministry of Rural Development (2011) Wooden Perches to Combat Voles. Ministry of Rural Development. Available from: http://www.kormany.hu/en/ministry-of-rural-development/news/wooden-perches-to-combat-voles

Taylor, M. (2011) Palm oil planters get wise with bird of prey pest control. The Owl Pages. Available from: http://www.owlpages.com/news.php?article=1003

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