Category Archives: Other Wildlife

Wildlife other than birds

A Bit Off Topic – Rodenticide Baits and Secondary Poisoning of Wildlife

Introduction

The official motto of Chicago is Urbs in Horto, which translates to “City in a Garden”, but it can also be described as a city overrun with rats. The pest control company Orkin has ranked Chicago as the rattiest city in the United States for nine years in a row. I worked for two years as a pest control technician and I oversaw the rodent control program for the Village of Niles in the summer of 2023. I’m also certified by the Illinois Department of Public Health for general use and restricted use pesticides. I have extensive, firsthand experience working with rodenticide baits to control rats and I saw the worst of the problem as a pest control tech in Chicago. The rat problem in Niles is a more recent phenomenon and not nearly as severe as it is in Chicago, though the drivers are the same.

The Problem (and why it’s so hard to get under control)

The Chicago rats we’re familiar with are Norway rats (Rattus norvegicus), a non-native species adapted to living in close association with humans in urban environments. This species has other common names like brown rat, sewer rat, and street rat, but I’ll refer to them as Norway rats here. Norway rats are almost entirely dependent on humans for food, water, and shelter; large cities like Chicago provide a near perfect environment for them to not only live but to thrive. The main driver of the problem is poor sanitation on the part of residents. This is common knowledge in the pest control industry and I experienced this almost daily while doing field work in Chicago, and to a lesser extent while working in Niles. Norway rats have food preferences but they are best described as omnivorous. Some of the contributing food sources I encountered while working in Chicago and Niles include dog feces, spilled bird seed, home grown garden vegetables, and fruit from fruit trees. This problem is simultaneously easy to remedy (remove the food sources the rats depend on) and intractable because of Chicago residents who don’t practice good sanitation and inadvertently feed rats and contribute directly to the problem. Throw in poor garbage disposal and you have a perfect storm of conditions that are responsible for the ongoing infestation.

Rodenticide Baiting as a Means of Pest Control

Rodent control bait boxes

Rodent control bait boxes (click to see the larger version)

A common method of controlling rats is to use boxes that contain rodenticide baits. You’ve probably seen these bait boxes and wondered what purpose they serve (and they’re hard to miss if you live in Chicago). Bait boxes are small, black or gray plastic boxes placed around the perimeters of buildings and other structures. Some of these boxes are shaped like rocks to blend in better with landscaping (the photo at right shows two such boxes). They have two holes, one on each side, that allow rats and other target rodents to enter and eat the poison laden bait inside. The only purpose of bait boxes is to hold rodenticide baits. They’re designed, as best as humanly possible, to keep people and dogs from accessing the bait, since the bait is harmful to any mammal that consumes it. The boxes are locked and can only be opened for servicing with a special key. This method of rodent control is inexpensive, easy to set up, and easy to maintain. More importantly, a bait box program covers a large area. When I worked for a pest control company in Chicago and for the Village of Niles, part of my job involved setting up and servicing these bait stations for our clients. I would determine where the best locations for placing the stations were, fill the stations with bait, and on return visits replace missing or old bait with fresh bait. The bait consists of a food attractant and a very small amount of poison. The poison is an anticoagulant that interferes with blood clotting and leads to death through uncontrolled bleeding. This use of anticoagulant baits is effective in killing rats and other target rodents, something I witnessed while working in Chicago and Niles. We also used old fashioned mechanical snap traps for rat control but snap traps are more labor intensive and messier to work with.

Drawbacks

The drawbacks of using anticoagulant baits to control rats are twofold. First, though effective, rodents eventually develop resistance to the baits, rendering them useless and requiring the development of new baits. We were using a second generation anticoagulant bait in Niles because rats had developed resistance to the first generation of baits. This is a common and recurring problem in pest control — companies develop poisons, the use of these poisons puts enormous selective pressure on target pests, because of the variation in the populations of these target pests some resist the effects of the toxins, these animals survive, reproduce, and pass along their resistant genes to their offspring. It’s a vicious cycle, and an inelegant way to control pests.

The second, more insidious effect is secondary poisoning of non-target animals. Predators like hawks and owls that consume poisoned rats take in some of the poison and become poisoned themselves. This is a well documented phenomenon and I won’t get into the details of it here. This article from the National Park Service offers a good overview of the problem — Avoiding Unintentional Poisoning.

Banning Rodenticide Baits Won’t Work

I’ve heard talk of moving to ban rodenticide baits. Despite their shortcomings, these products work well at controlling rat numbers; without them, or an effective alternative, Chicago’s rat problem would be even worse. Such a ban would face stiff opposition from the many pest control companies that operate in the Chicago area and who depend on rodenticide baits for their business. Opposition would also likely come from the Chicago municipal government, since the City uses rodenticide baits as part of its own rodent control program.

Challenges and Possible Solutions

Using rodenticide baits to control rats only addresses the symptoms of the problem and not the underlying causes, which are usually sanitation issues. Getting enough people to clean up after their dogs, clean up spilled bird seed, pick up fallen fruit from their fruit trees, and address other contributing factors is a tall order, especially in a city as large as Chicago. Proper sanitation would reduce the need to use rodenticide baits to control rodents, reducing the incidences of secondary poisoning of wildlife. This isn’t difficult to understand but getting everyone, or at least enough people on the same page won’t be easy. Hiring a pest control company to set up a baiting program to control rats is easier, which is why so many landlords and property management companies choose this option.

So what can be done? If we’re going to change behaviors we need to start with ourselves and work outwards. Be part of the solution by not contributing to the problem. Practice good sanitation on your own property. Talk to your friends, family, and neighbors about the connection between poor sanitation, the use of rodenticide baits, and secondary poisoning of wildlife. Here are some tips to keep rat numbers down and lower the chances of incidental poisoning of non-target animals and people.

  • Clean up dog waste in your yard and don’t let it sit overnight. Rats love dog poop.
  • If you have bird feeders, clean up spilled bird seed or install a screen underneath the feeder to catch the seed before it reaches the ground.
  • Consider removing your fruit trees or at least don’t leave fallen fruit on the ground.
  • Consider removing your garden vegetable plants and don’t let the vegetables stay on the plant longer than necessary. You might also consider installing fine wire chicken mesh around the plants to make it harder for rats to access the vegetables.
  • Rats need standing water to drink. If you have an unprotected koi pond, rats will drink the water. Consider removing the koi pond or installing fine wire chicken mesh around it.
  • Properly dispose of your garbage. Poor garbage disposal is a big problem in Chicago and a driver of our rat problem. To illustrate this point, I once found whole lobster tails in an alley behind a building in the Loop my company had a contract with. Lobster tails. Chicago rats are probably eating better than most of its human residents, which is why the rats are thriving. Make sure your garbage cans have tight fitting lids, don’t let garbage bags spill out of the can, and make sure rats haven’t chewed holes in the plastic cans to access food (they can and will do this).
  • Don’t ever use OTC rodenticide baits for personal use. You might kill rats but you’re just as likely to kill native wildlife like chipmunks and squirrels and you could harm or kill pets. I saw this firsthand while working in Niles.
  • Don’t ever use anticoagulant rodenticide baits for personal use. You can buy these products online from Amazon and you don’t need a license or certification. Try it yourself. Go to Amazon and do a search for First Strike soft bait. This is the same product we used in Niles when I worked for the Village government overseeing its rodent control program. This and similar anticoagulant rodenticide baits are dangerous and heavily regulated by the government. If you don’t know what you are doing you could harm or kill native wildlife, pets, and people. The criminal penalties for misuse of these products are severe.

A broader, large scale education program similar to Cats Indoors might be worth considering. Such a program could emphasize the connection between sanitation, the use of rodenticide baits, and the effects these baits have on wildlife. If it reaches enough people it could change behaviors and lead to a decrease in rat numbers and less need to use rodenticide baits.

Final Thoughts

This isn’t an easy problem to solve. As I try to emphasize here, getting enough people on the same page is the biggest hurdle. I’m probably being overly optimistic about the chances of success but addressing the underlying cause seems to be the first place we should start.

Structural Pest Control Certification

Illinois Department of Public Health pest control certifications

Winter Birding Ideas – The Kankakee Sands

Rough-legged Hawk

Rough-legged Hawk (click to see the larger version)

The Kankakee Sands is a complex of prairie and wetland habitat owned and managed by the Indiana chapter of The Nature Conservancy. Birding is excellent all year round. Summer is the season to see the grassland specialties like Henslow’s and Grasshopper Sparrows and Dickcissel, which are hard to miss and fill the air with their songs. Winter brings a different set of visitors, most notably birds of prey like Rough-legged Hawk, Northern Harrier, and Short-eared Owl (the owls are best seen at dusk). The main mammal claim to fame is a herd of about 70 American Bison. These iconic North American animals were introduced to the Sands in 2016 and play an important role in maintaining the integrity of the grasslands.

How to Bird The Kankakee Sands (and look for Bison)

The Kankakee Sands is about an hour and a half due south of Chicago off US41 in eastern Newton County, Indiana. Morocco is the nearest large town and lies about six miles to the south. When I bird the Sands, I drive slowly down county road 200W between county road 675N on the north and 225N on the south, looking and listening for wildlife. These roads don’t get a lot of traffic, especially in winter, and are generally safe to drive. County roads 500N and 400N east of US41 can also be productive for birds of prey in winter. Note that in winter the roads might not be drivable because of heavy snow.

American Bison

American Bison (click to see the larger version)

The Bison are best viewed from the Bison Viewing Area west of US41. To reach it, take 400W south from 400N for about half a mile. Look for a gravel road that goes east and take it to the parking lot. Walk up to the top of the rise and start scanning. The Bison are usually to the south, east, or northeast. You can usually see them with your eyes but binoculars make the experience more enjoyable. This is also an excellent place and vantage point to look for Rough-legged Hawks, Northern Harriers, and other winter birds of prey. I’ve included a link to my January 9, 2021 Kankakee Sands eBird checklist to give you an idea of what I saw on that visit.

To read more about The Nature Conservancy’s efforts at Kankakee Sands, go to this site – Efroymson Restoration at Kankakee Sands.

Kankakee Sands eBird Checklist
January 9, 2021

Mudpuppy, April 12, 2023

Mudpuppy

Dead Mudpuppy at Montrose (click to see the larger version)

Montrose is known for all kinds of critters but we don’t do well with amphibians. Part of the reason for this is that Montrose doesn’t have much in the way of amphibian habitat. We used to have American Toads in the pannes, sometimes in the hundreds, but the pannes dried up recently and the toads disappeared.

The Chicago area is home to a large salamander called a Mudpuppy. They’re in Lake Michigan but since Mudpuppies spend their entire lives under water we don’t see them, unless a fisherman accidentally catches one. This is what must have happened to the dead 10 inch long Mudpuppy on the fishing pier on April 12. The Mudpuppy either grabbed the bait or was incidentally snagged by the hook. The unsuspecting fisherman probably thought he caught a salmon. When he reeled it in he realized he didn’t have a fish but something else entirely, something weird and alien looking, like a miniature version of the creature from the black lagoon. Out of frustration, or panic, he threw it on the pier, where it died, an unfortunate end to a fascinating native animal.

Little Troublemakers

Presumed Zebra Mussel shell from Montrose Beach

Presumed Zebra Mussel shell from Montrose Beach (click to see the larger version)

Almost every square foot of Montrose Beach has Zebra or Quagga Mussel shells. These invasive, non-native mollusks have altered the ecology of Lake Michigan and created problems for commerce. It’s hard to believe something so small can create so much trouble for people and the environment. One positive aspect of their presence is that they provide food for several species of duck, like Common Goldeneye and Greater Scaup.

The photo shows a presumed Zebra Mussel shell. The shell is bleached from exposure to the sun and blowing sand, but you can still see how this species got its name. The next time you’re at Montrose Beach, try finding both Zebra and Quagga Mussel shells. The Nature Spot website has a great section on how to identify the two.

Something Fishy

Lake Trout

Lake Trout (click to see the larger version)

Ah, there’s nothing like seeing a dead fish to lift the spirits. I usually don’t post photos of deceased animals but this one is worth mentioning. On November 29, 2022 I found a washed-up Lake Trout (Salvelinus namaycush) on Montrose Beach. This might be the first Lake Trout I’ve seen at Montrose. Most of the large predatory fish in Lake Michigan are non-native and introduced, like the familiar Chinook and Coho Salmon. Lake Trout were once the dominant large predatory fish in the Great Lakes; lamprey predation, pollution, and overharvesting greatly reduced their numbers. Thanks to conservation measures, they’ve rebounded but they aren’t as common as they once were.

Identification: We know this is a Lake Trout and not an introduced salmon because of the small white spots on the body and the deeply forked tail. Our non-native salmon have dark speckling on their bodies and shallower tail forks.

Something Different – The Amur Cork Tree

Amur Cork Tree and a Hermit Thrush

Amur Cork Tree and a Hermit Thrush (click to see the larger version)

One of the benefits of birding is that it touches so many other disciplines – you end up learning something about botany, entomology, weather, even physics. Montrose hosts an impressive variety of trees, including an exotic Asian species known as the Amur Cork Tree. Most naturalists don’t think highly of non-native plants because of the adverse effects they can have on the environment. One redeeming quality of the Amur Cork Tree is that it produces large amounts of juicy berries that fruit eating birds like American Robins and Hermit Thrushes love. The photo shows one of the Cork Trees from Montrose. Note the clusters of dark berries and the Hermit Thrush about to eat them.

The next time you’re at Montrose, practice your tree identification skills and see if you can find our Amur Cork Trees.