Garden Notes: Integrated pest management

Barn owls can help control rats, voles, mice, and more.


Not much winter, so far. The “new normal” action seems to be that it starts later and goes longer into spring. Snowdrops and pansies are in bloom. If we want to change actions, attitudes must change. “All things are interconnected. Everything goes somewhere. There’s no such thing as a free lunch. Nature bats last.” –Four Laws of Ecology, attributed to Barry Commoner.

Use and Re-use

In January multiple news outlets carried shocking images of plastics, heedlessly discarded by humans, choking the Drina, one of the most beautiful and storied of Balkan rivers.

Who is heedlessly dumping all this stuff, and what else is being dumped? Here on the Island — we are. The Island increasingly experiences flooding; the plastics and trash and PFAS wash and slosh along with the water, which always seeks its own level: the water table or ocean.

All plastics contain toxic components and take a toll on our environment, and us — exposing us all to pervasive ill health threats we are unable to avoid. Just a few instances of harms: nanoplastics found in babies’ placentas, pollution, endocrine disruption, expense and logistics of waste disposal, cancer. Think about it.

Recommendations for serious winter reading: “The Story of Stuff,” by Annie Leonard; “Cradle to Cradle,” William McDonough and Michael Braungart. These reveal ways going forward, and much, much more. Cultivating ways to restrict, use, and re-use it all, with as many repeats as possible, are ways to become more plastic-aware Islanders.

Rats and Raptors

Encouraging the Island population of owls, especially barn owls, by habitat preservation and nest box building, could help control Island rodents.

When they built their barn, our barn owl loving neighbors up the hill installed an owl box. Barn owls eventually moved in and last year produced four owlets, which may have dispersed locally, since another nest box nearby recently also became tenanted. I borrowed books on owls from them to inform myself further.

My original sub-head was pedestrian: “Barn Owls,” but “Rats and Raptors” is catchier. Rodent infestations have become an Island-wide problem, and raptors, an avian category with hooked beaks and sharp talons, are part of the solution. However, quoting Gus Ben David, an important factor is “Predators do not control prey; it is the prey that controls the predator.”

Scarcely any households or gardens, from fancy to humble, are unaffected by rodent problems. You name it — voles, rats, chipmunks, and mice are creating problems up-Island and down-Island. For tomato growers especially, rodents’ damage to crops is painful; but damages run the gamut when rodents cohabit in our domestic spaces, even our automobiles!

Many issues, as gardeners and farmers have learned, represent problems in unbalanced ecologies, systems out of whack, which respond to measures called Integrated Pest Management (IPM).

Are increasingly used dumpsters a piece of this? Is there a bumper crop in berries and seeds that supports rodents? Are bird feeders encouraging rodent population explosions? Do home compost piles add to the problem? Are extensive groundcovers, such as vinca and English ivy, contributing?

Does a slump in the raptor population graph equal an upswing in the rodent population graph? Are rodent populations evolving ahead of control measures? (Anecdotally, New York City rats have developed a taste for dog poop and are said to be thriving on it!)

Egyptian cat worship? Cheering on coyotes? There are no simple answers, in spite of the near-universal complaints all around the Island. Sure, many will resort to using poison baits, a short-term answer: over time they fail to make a dent and  — “everything goes somewhere” — add poisons to the food chain. Eventually they come back to bite non-target wildlife, our pets, or ourselves.

Many Islanders were captivated by the Felix Neck barn owls via video cam in their nest box, or have heard about barn owls at other Island farms; but may have assumed that providing nesting opportunities requires equivalent locations.

Not so. According to the three borrowed owl books, barn owls (Tyto alba) occur worldwide except Antarctica, and are comfortable nesting in built up areas if they find suitable accommodations. A shed or barn frequented by rodents is superbly suitable, although we have fewer of these now than we did “back in the day.”

Barn owl populations are declining in many parts of the country, as is the case here, caused by changeable winter weather patterns, by lack of nesting and foraging conditions, plus the effects of pesticides in the food chain.

Cavity nesting owls utilize tree holes that woodpecker populations drill in mature woodland. Barn owls usually mate for life and accept a variety of nesting opportunities, including cavities in trees, cliffs and rocky outcrops, outbuildings and barns, steeples, and nest boxes. Installing nest boxes may not result in immediate occupancy — that may take time but is no reason to not to take the first steps.

Barn owls, being a colonial species, are even tolerant of sharing their territory with other barn owls. Most owls roost during the day and forage at night, with barn owls preferring open areas such as fields and grasslands, or marshes.

Owls As Integrated Pest Management

Integrated Pest Management (IPM) attempts to use known ecological elements, such as predators, to arrive at solutions to vexing problems, such as rodents. I want to give a shoutout to BiodiversityWorks:, the Island non-profit that studies Island-wide bio-life, and which may be best positioned to monitor barn owls and their IPM possibilities.

Ben David mentions the importance of voles as barn owl prey; and those owls’ numbers fluctuate downward precipitously when we experience snowy winters. Voles remain under snow, scurrying to and fro and leaving tracks visible after snow-melt. Barn owls are unable to hunt them then, below the snow, the resulting starvation thinning their numbers.

Nine other owl species, all members of family Strigidae, (two of which are either endangered or of special concern) are resident here. They join Island barn owls (family Tytonidae) in eco-rodent predation, either permanently or as vagrants. All hunt good numbers of typical small rodents, with the addition of rabbits, small fish, reptiles and amphibians, insects, bats and birds, as do daytime raptors.

Can we interest 4-H clubs or MVRHS’s VocEd program in an unpretentious barn owl nest box construction project? (Offer them for sale on Earth Day?) The pdf linked contains construction details:



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