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  • What You Need to Know About Feeding Wildlife in Your Backyard

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    Tags: feedings, animals, wildlife, birds, squirrels

    Created: 10/31/2014      Updated: 8/8/2016

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    I have recently received many questions about feeding animals so I thought a general discussion about backyard feeding of animals like birds and squirrels would be useful. Feeding animals can be fun and it provides an opportunity to watch the animals closely. On the other hand, feeding can concentrate diseases dangerous to the animals and sometimes to you, and can attract pests and predators.  

    Birds on birdfeeder

    To deal with the disease problem keep your feeders, baths, and the area you feed in clean and sunny. Also keep an eye on frequently used perches and loafing areas. Remove food debris daily, hose down everything with water, use soap when appropriate (I like Dawn best—skip anti-bacterial varieties) and use a mild bleach solution to regularly clean bird baths, feeders and other appliances. Rinse and dry well. UV light is your friend -- it kills most disease causing organisms pretty quickly but it doesn’t penetrate shade or underneath objects. 

    You might also consider moving your feeding site around. It’s difficult to remove every last bit of chaff, crumbs, and poop, but ants, earthworm, millipedes and many other garden organisms will do the final cleanup for you. While these invertebrates are beneficial components of our neighborhoods, rats and mice are pests that will also move in to clean up debris from your feeding stations. The reason rats and mice are a problem is because they can cause substantial economic damage through their gnawing and foraging activities. More importantly, they can carry diseases that can be readily contracted by humans. Many municipalities have banned bird feeders simply because they quickly become rodent feeders and thus a public health concern. By keeping a scrupulously clean feeding station, you greatly minimize the chance of making your yard a vector of human or wildlife disease.

    Squirrel eating

    Although you may have certain species in mind when you put out a feeder, many species will be influenced by the additional food you have introduced to the environment. To maximize the chances of seeing your target species, make sure you are providing the most appropriate food. If you want to see goldfinch, you must supply thistle seeds. If you supply hazelnuts you might see squirrels and woodpeckers, but sparrows will ignore you. Cracked corn is, in general, just a filler that does little to attract the species most people want to see. If it is present in your seed mix, there’s a good chance it will be tossed out of the feeder in favor of more palatable food like millet only to later attract rodents. Regardless of what you put out though, you will also attract non-target species. Sugary hummingbird feeders will also give you a chance to watch a variety of bee species. Seed feeders will often bring squirrels to your yard, but the songbirds they attract will also bring raptors. These birds of prey can’t feed their young on seeds, they must have meat. Don’t feel badly if you find feathers and other sign of a predation even hear your feeder. This is simply an indication that nature is at work in your neighborhood maintaining the strength of your avian friends and increasing biodiversity.

    If you want to minimize predation you can feed infrequently or move your feeder around regularly. While this will keep the predators guessing, it will also keep your target species guessing so you might not see the large and regular concentrations of birds that you would with a more regular feeding time and place. Of course, if you are unlucky enough to live in a place where cats roam at will, nothing you do will be enough to prevent predation and you will have less diversity at your feeders.

    Finally, when choosing a place to put your feeder, make sure you don’t become the predator — via your house. Windows can kill a lot of birds. During the day, birds usually hit windows because of a mirror effect where the window looks like open sky or a sheltering bush. At night, lights lure birds too close. There are many online resources to help you determine how to prevent your house from becoming a deathtrap. Making the windows visible is important. It’s hard to avoid putting feeders in places where there is some danger from windows though, since a primary reason for feeding animals is to see them better. So, in general, feeders should be sited close to the windows. This not only improves viewing but it also limits the danger of windows for birds because, if they are frightened when at the feeder and take off in the direction of the window, they aren’t flying very fast when they hit it. If the feeder is further, the bird gathers enough speed to cause a concussion when it hits.

    Steve Sullivan, Senior Curator of Urban Ecology

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  • Rodent “Pests” and How to Deal With Them

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    Tags: rats, mice, squirrels, chipmunks, pests, pest removal

    Created: 10/15/2014      Updated: 8/8/2016

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    First, let’s get one thing straight. Pests are only pests because they’re doing something that interferes with something you want to do. Western ranchers view wolves and bison as pests; pelicans and cormorants are pests to some fishermen while snakes and otter are pests to others; a bobcat is beautiful to most people but can be a pest to a chicken farmer.

    Squirrel in trash can

    That said, rodents can significantly interfere with some of our goals related to our gardens, homes, and health. The range of solutions to the problem is more or less the same regardless of whether we’re dealing with a mouse, vole, chipmunk, tree squirrel, or even a lot of non-rodents.

    Poison

    I don’t like to use poison in most cases. First of all, any poison that can kill one kind of mammal, can kill any other kind of mammal; this includes you, your neighbors, and many pets. Such poisons usually also kill birds, reptiles, and fish. 

    Block of rodent poison

    To reduce the likelihood that “non-target” species will ingest the poison, it is mixed with wax, grain, and flavoring to form a little block that is then put into a plastic box that the rodent has to crawl into to access the poison. However, if the poison killed quickly, the rodent population would eventually figure out that they shouldn’t eat it. Instead, many of these poisons work by making the gastrointestinal tract leaky. Essentially, over time, whatever ate the poison will bleed to death internally.

    Poisoning is a slow death. Worse, the animal may die in a place where a dog or cat, hawk or owl, or some other animal may eat it, then die of secondary poisoning. Assuming the poisoned pest is not eaten, it may die inside your wall or crawl space, often making quite a stink. The stink is relatively short term though and when it goes away you may think all your troubles are over. However, you now have a mummified body in your wall which will attract a wide range of insects, notably the Dermestid.

    Dermestids are a kind of beetle which, as larvae, feed on dead, dry flesh. They will also feed on leather, fur, wool, and many other fibers and textiles. They can very quickly build up large populations even on something as small as a mouse carcass. Eventually they spread through the house and will happily eat that nice jacket you stored away during the summer, or your carpets, even the feathers in your pillow. Having eliminated a single rodent pest by poison, you now have hundreds or thousands of insect pests to deal with.

    Sometimes though, poison is the only solution. It can be used very effectively when deployed and monitored by trained and dedicated people. But, in a household situation, poison is rarely a good solution and often causes more problems than it solves. Instead, try one of these alternatives:

    Trapping

    For a problem that is acute – that is you have a pest currently causing damage – a trap can solve the problem quickly. Snap traps, box traps (like the Tomohawk or Havahart for large animals, or the Sherman for small ones), repeating traps, and sticky traps are all options, but some a better than others.

    Rodent snap trap

    I like snap traps. When baited correctly in a household situation, they rarely capture non-target species. They usually kill cleanly and humanely without any training on the part of the operator. They don’t need to be monitored because either they caught something and killed it or they didn’t catch anything. If you’re afraid of catching your fingers while setting traditional snap-traps, shop around for plastic ones that can be set by simply stepping on a treadle.

    Box traps and repeating traps are very useful but have two problems for the homeowner. They need to be monitored daily to ensure trapped individuals don’t suffer for lack of food and water. Monitoring has the added problem of disturbing the site and reducing trap success. The worst problem though, is that once you catch something, it has to be killed. Most homeowners simply don’t have the skills to humanely and cleanly kill rodents.

    The challenges of monitoring and euthanasia are compounded with sticky traps. From the moment the animal enters the trap, it begins suffering. These traps capture a wide range of non-target species, including reptiles, amphibians, and birds. Vegetable oil can be used to free an animal from the goo but a residue will remain that can impede movement and grooming, and the stress of handling is often enough to kill the animals a short time later. There are small sticky traps with a very thin coating of goo that are designed to aid in insect monitoring. I use these regularly but I don’t see any good reason to use the sticky traps designed to catch rodents.

    In household situations, I advocate strongly for snap traps. Regardless of situation or trap though, trap placement will strongly influence trapping success.

    Steve Sullivan, Senior Curator of Urban Ecology

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  • How to Eat, but Not be Eaten — Foraging Strategies of Four Urban Squirrel Species

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    Tags: squirrel, squirrels, urban ecology, chipmunks, chipmunk, chicago, chicago wildlife

    Created: 9/19/2014      Updated: 8/9/2016

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    The most common tree squirrels in our region are the grey (Sciurus carolinensis) and the fox (S. niger). Both of these species are scatter hoarders. That is, they bury nuts in random places across the landscape. In contrast, the red squirrel (Tamiasciurus hudsonicus) is a larder hoarder. This means they put all of the food they have gathered in only a few places, like a hollow log or under a rock.

    Grey Squirrel digging in the ground

    Grey squirrel caching

    These two strategies have costs and benefits. A larder hoarder can defend its cache from other squirrels, nut and seed eating birds, and many other species that might rob it of food. Even you may have been scolded by a red squirrel when you inadvertently came too close to its larder. On the other hand, there’s not much a red squirrel can do to deter a determined black bear from raiding the squirrel’s cache. Scatter hoarders don’t have to worry about bears but they do lose a lot of their nuts to competing squirrels and birds, and simply because they can’t find the food once it is buried.

    Fox Squirrel eating in a hole in a tree

    Fox squirrel eating

    These two different foraging methods also result in red squirrels having relatively large territories. You don’t often see lots of red squirrels in the same place at the same time. On the other hand, there are many places where you might see more than a dozen grey squirrels foraging together. 

    Red squirrel on a rock

    Red squirrel

    One thing that does bring lots of squirrels together is bird seed. If seed is buried it either rots or germinates. Either way, it is not very useful to squirrels so, rather than run around caching, as they do with nuts, squirrels will simply sit and eat the seed. The threat of predators and more aggressive squirrels keeps them moving around a little but they are otherwise perfectly happy to sit at the dinner table and eat.

    Chipmunks, though, have a different strategy. They have check pouches. This allows chipmunks to literally stuff their faces full of food, then run back to their burrow, dump the food, and return for more once they think the coast is clear. In this way, they can collect plenty of food to eat, while only exposing themselves to the danger of predation for relatively short amounts of time. The seeds they gather are stored in cool, dry rooms (the same way we store grain) so it stays fresh and nutritious through the winter. This foraging strategy is so successful that chipmunks have become our most common ground squirrel in urban areas.

    Have you ever wondered why you don't see baby squirrels as often as you see adult squirrels? Learn why in this post.

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  • A Biologist's Point of View

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    Tags: squirrels, parks, hunting, extinction, human nature interaction, fox squirrels, grey squirrels, elk, bobwhite, settlers, Biology

    Created: 12/11/2013      Updated: 8/9/2016

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    After reading yesterday's Gizmodo article titled "The Fascinating Story of why U.S. Parks are Full of Squirrels" by Adam Clark Estes, we had our Curator of Urban Ecology and resident squirrel expert (he runs projectsquirrel.org, a citizen science project) Steve Sullivan, write a response. The result is a historic and eye-opening look into the population of squirrels (and other game animals) from a biologists point of vew.

    This is a fun article as far as it goes. It neglects two important points though, one having to do with extirpation and the other with invasion.  

    Eastern grey squirrel
    Eastern grey squirrel

    Sure, we encouraged squirrels to live in parks. Wildlife of all kinds has potential to bring joy as we watch and interact with it. In fact, there is a claim (I’m still looking for the primary source) that Oak Park reintroduced fox squirrels by trapping some in Oklahoma. So why did we have to add squirrels to our parks and why did Oak Park have to import them from so far away? Over hunting and habitat destruction.

    As settlers spread they relied on wild game to supply much of their food. Since we need to eat all year, people were hunting and trapping all year. Bison, deer, and turkey are the ones we often think of in this context but in fact beaver, bear, bobolink, lark, curlew, duck, prairie chicken, and even squirrel were also on the menu. In fact, small animals like squirrel and many birds were likely on the menu more often than the larger species. Remember, prior to the present era, people ate far less meat than we do today and two or three bobolink were more than enough meat for a meal; a squirrel could feed four people.  Nevertheless, relentless hunting reduced populations of these species significantly. Many that were once common disappeared from many states, some became extinct. Only a few decades ago, it was uncommon to see a deer and unheard of to see a turkey. Bison are found almost exclusively in preserves and elk are rare outside of them. Bobolink, duck and lark populations are tiny compared to pre-settlement times. Eskimo curlew are extinct (we ate them all) as are passenger pigeons, a species that was once one in four birds on our continent. During this time, squirrels diminished greatly, too. 

    Bull Elk
    Bull Elk, photo by Flickr user Amada44

    Thankfully, uncontrolled hunting (in the US) has been largely solved. Hunting seasons, animal censuses, and hunter success reports ensure that our favorite game animals are almost all doing very well. So well, in fact, that many species have become pests in places where hunting is limited. 

    While we may have a good handle on over hunting, habitat loss is another issue altogether. One game species that is not doing so well is the bobwhite quail. This once seemingly ubiquitous species is seldom seen in many places where it once was about the only thing worth hunting.  It is declining for a number of factors, most notably habitat loss. As farms are consolidated, fencerows are eliminated. These fencerows once provided shelter from the wind and rain for a wide variety of species.  Without them, the landscape becomes little more than a biological desert of corn and soy fields.  Almost nothing lives in these places, especially not game animals. 

    Bobwhite
    Bobwhite, photo by Steve Maslowski/USFWS

    Thankfully for squirrels, the parks we create are often hospitable environments. When we make parks, we typically eliminate most of the natural biodiversity. Notably, we eradicate predators to the best of our ability, and we plant as many trees as we can. Both of these cases greatly benefit squirrels. As the article correctly points out, it is sometimes necessary to install nestboxes because we also remove large hollow trees just as they become naturally good homes for squirrels. Not all species respond well to such simple manipulations though. Think how hard it is to get a bat box populated.

    And so, these days, after killing off most of the squirrels near us and destroying their habitats, we have created parks where they can live and, in many cases (but certainly not all), we have intentionally reintroduced them as a mobile part of the natural beauty we maintain in our cities. 

    Fox squirrel
    Fox squirrel

    Invasion is another story. The grey and fox squirrels that many of us are so familiar with are native to the eastern half of our continent. There are other tree squirrel species that evolved in the more diverse western ecosystems. However, as we settled the west, we brought our squirrels with us. The native species were sometimes shy, occurred in low numbers, or were too greasy; they were hard to hunt and not much good for food. So, we introduced the greys and foxes into these new ecosystems and, much as they took to the artificial habitats of parks, they also prospered in western habitats. 

    Eastern grey squirrel
    Eastern grey squirrel

    Today, Eastern grey squirrels (Sciururs carolinensis) are invading the habitat of Western greys (S. griseus) and eliminating them. Project Squirrel participants may also be documenting a new invasion of fox squirrels in Colorado where they compete with Abert’s squirrel. Fox squirrels are also well-established in the Los Angeles region and are a major pest in some nut farms. Both grey and fox squirrels can also cause major damage to natural forests as they eat and scatter nuts and remove bark from trees. Over time, we expect them to change the look and feel (and thus the resident animal populations too) of some western forests. These same problems are being experienced in England and Italy where our grey squirrel has been introduced.

    So, while it is enjoyable to watch squirrels in eastern parks, those that you see in western parks are often an indication of significant ecological problems brought about by people moving squirrels around.



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  • Project Squirrel Foraging Data

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    Tags: project squirrel, foraging data, citizen scientist, squirrels

    Created: 5/23/2013      Updated: 8/10/2016

    Squirrel eating corn

    Project Squirrel will be conducting foraging studies on urban squirrels throughout the summer. Members of our team will put out foraging trays like these on at least four consecutive days twice in a month. Trays are placed in the morning and retrieved each evening. Data are collected by looking at how much corn was consumed and how it was consumed. We would like to increase the number of sites we are studying. If you live in or near Oak Park or River Forest and have a tree 15 cm in diameter at breast height in both the front and back yards and might be interested in letting us use your yard for the study, please email Steve for more details.

    Steve Sullivan, Senior Curator of Urban Ecology

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