Squirrel damage to Austin trees

Squirrels in the Austin area are considered cute to many local Austin area residents. We like to watch them play and chase each other around the tree trunks and across the lawns. We like to watch them sun themselves on the tree trunks, and many people feed them to help promote their presence in the landscape.

This all would be great if they were not destructive to local trees and even homes! Many people do not know that squirrels destroy trees by stripping the bark off local trees and even stripping insulation from attic wiring! Often soffit and insulation damage occurs as they chew into and around the attic and roof areas.

In many parts of town, especially areas with a large urban forest, squirrel populations have exploded. With large amounts of food such as acorns and pecans, not to mention bird feeders, and virtually no natural predators, there are simply too many squirrels per acre. When the squirrel populations explode, trees suffer.

Maples, cedar elms, lacebark elms, hackberry trees, mulberry trees and red oaks all suffer damage from squirrels. They strip off the bark on the tops of limbs, sometimes ‘circumventing the cambium’ or stripping the bark off all the way around the limb, killing the branch from that point to the tips. Often they strip the bark from the upper sides of large limb crotches, drying out the limbs and weakening the unions, causing limbs failure.

In certain cases, I have even had to remove trees due to excessive squirrel damage causing large, continual and dangerous limb failure. Why do they do this? Apparently, they are eating the stored sugars made by the leaves in the summer, and that are now stored under the cambium and other cells under the bark. They often peel the bark off in strips, and may also be using it to line/weave their dens. They like the thinner, smooth barked trees and branches on the species listed above.

Squirrels do not hibernate, and may have as many as three dens they frequent at any one time. Their food sources are typically lower during the winter months and early spring, so this is when most damage occurs. Limiting and/or reducing squirrel populations is a good idea, but can be extremely difficult, time consuming and often costly. I have spoken to customers that have trapped and moved scores of squirrels with no apparent dent in the local population. Properties backing onto greenbelts are especially problematic when it comes to all wildlife, and squirrels are no exception.

In areas with fewer trees, squirrels are less prevalent and also easier to keep out of the trees. There are ways to wrap the trunks with inverted metal cones, raise low limbs, clear limbs back from roofs and sometimes separate the trees to keep the squirrels out of the canopies in these areas. Sometimes dogs in the yards also help scare the squirrels off. Keeping bird feeders out of the trees completely or putting up squirrel-proof bird feeders is also recommended. There are also several other home remedies for keeping out squirrels such as moth balls or predator urine, but that don’t always work well.

Grackle Control: Managing flying pests

Grackles are messy, black to brown colored birds that flock in large numbers in certain areas of central Texas.  They feed on garbage, generally out of dumpsters, and are extremely messy when they roost in dense trees in or near parking lots and defile the parking areas, vehicles, bus stops, etc . Grackles are becoming a vastly more severe pest problem as the years go by in Central Texas, and various methods are being explored to control them.

Years ago I attended an interesting seminar on grackle control by a Texas State Park official who worked in the Dallas area.  His area was so badly infested with grackles, that he was actually imlementing shooting off ‘whistlers’ to control grackles.  These ‘whistler’s are actually a type of shotgun shell that is fired into the air, creating a whistling sound culminating in a explosion that temproarily scares off grackle flocks from their roosting areas.  Although effective, it is loud and disruptive, and there are certain areas where this simply cannot be employed.

I have found thinning dense trees in high impact areas to be quite effective at controlling grackles. Thinning needs to be done anyway, not only to reduce potential storm damage to landscape trees, but can also be highly effective in reducing grackle roosting problems.

For example, in several instances in 2010, we thinned trees out in several different shopping centers that were having grackle infestations. After the trees were thinned, the grackles no longer had the cover of the dense foliage, and have since moved their roosts elsewhere. At the Tech Ridge Center at Parmer and I-35, the property manager was looking at installing an extremely expensive grackle control misting system to all affected trees.

This system had to be hot-wired into the ground at all tree islands in the parking lot, and was supposed to expel an irritant at certain times to repel the pests.  After thinning out the landscape trees early in 2010, we are now experiencing such a decline in grackle activity that they are not considered to be a major problem at this time.