Archive for the ‘Rats & Rodents’ Category

– I’ve noticed that one of the favorite points of entry for rodents in brick homes, mice in particular, is through the expansion joints between the bricks. There are purpose made products out there for sealing these gaps, but I just use crumpled up chicken wire to shove in the joints. The chicken wire still allows the brick to expand. When the brick contracts, it leaves a bit of a gap, but the wire ends discourage rodents from entering.

– All gaps leading into your house should be sealed. Steel or copper wool and scourers are useful in tricky places.

– Compost bins are unfortunately a draw card for rodents. Where possible, get your compost bin off the ground, but drill small holes in the base so moisture can still drain away. Avoid putting food scraps into a compost bin – a worm farm may be a better option.

– Keep your yard as clear as possible of piles of debris and regularly check under logs and rocks for signs of nesting. Disturbing the area regularly will discourage rodents from establishing themselves, and in the process you can also get rid of pesky snails and slugs.

– Mice need very little food to survive, so regular sweeping of your kitchen area will help deprive them of sustenance and a reason to hang around.

– If you’re in a rat prone area, use metal garbage cans instead of plastic ones – rats will attempt to chew through the plastic bins.

– Fallen fruit should be removed from under trees.

– If you’re building a new house or considering re-insulating your current home, consider recycled cellulose fiber – it’s a highly effective “green” insulating material and the (safe) chemicals it’s treated with discourage rodents from nesting in it.

– Rats and mice love seed, so if you do have a bird feeder, try to keep it as far away from the house as possible and in the open with nothing that could be used as a rodent hideout nearby.

– With your recycling items, ensure cans and soda bottles are stored in sealed containers or bins

– Mice love to eat soap (go figure) so store any soap you keep outside in a container. They’ll also eat leather and cloth if other food sources aren’t available.

– If your cats and dogs “graze” don’t leave their pet food out for long periods; particularly overnight.

– Speak to your local pest control company about alternative trapping and repelling methods such as ultra-sound and electric zappers.

– I’ve read that rodenticide products containing Calciferol (vitamin D), cholecalciferol (vitamin D3) and ergocalciferol (vitamin D2) are less likely to cause secondary poisoning of other animals. It’s still deadly to many animals if consumed, so treat it with the same care as you would the other poison and it should be placed in tamper proof bait stations.

– If you use snap traps, peanut butter is great bait. You can also put the trap inside a paper bag so you don’t need to handle the animal once it’s been trapped. Be sure to place the traps where you know other small animals won’t get to it.

It’s recommended not to reuse a snap trap as the scent of the dead mouse or rat will repel other rodents. Given that, it’s a little expensive and wasteful having to buy a trap each time, but if you choose to do so, buy the ones made of wood, not plastic.

– Live traps can be re-used; in fact, by leaving a single mouse in a live trap, it will attract others (not the case with rats though). How to humanely dispose of the live mice is another issue. Ideas anyone?

– Get a dog. Not a cat, a dog. A terrier to be precise. Fox/Jack Russell terriers are the best mousers and ratters around. Terriers do not play with rodents like cats will, they kill them extraordinarily quickly; so it’s a little more humane I guess. If there are multiple mice, a fox will kill one and immediately move onto the next – I’ve never of dogs dogs actually eating one. Fox terriers can be trained to leave other animals alone – for instance, you can train them to become super assassins with mice, but to learn to leave birds alone. Cats on the other hand are more indiscriminate killers; cause massive problems in relation to native wildlife and it’s my understanding that they are pretty much useless when it comes to rats.


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Rodents and Compost

Mice and rats can make great pets if you like that sort of thing, but they are terrible pests to have running around the garden. I greatly dislike killing cute little mice or even rats for that matter, but letting them run rampant presents hygiene and safety issues.

Mice and rats are well known for chewing through electrical fires and wreaking all sorts of structural havoc as well. Finding mouse and rat poop around the compost, garden and patio is not a particularly appealing occurrence either. So controlling these critters especially once you start to actively compost your greens and organic waste poses a problem for many residential home owners and community.

There are a few ways to approach the issue from green approaches, to controlling the population growth of rodents to traps and of course chemical means.

A greener approach to rodent control

Most rodenticides you buy in the supermarket contain rather nasty ingredients including Warfarin, Bromadioline or Brodifacoum. These chemicals are brutal on the animals. They die horrible deaths through internal bleeding and it can take anywhere from 3 – 10 days for death to occur.

Aside from the cruelty aspect to the rodent; given the length of time it takes for the animal to die, they tend to continue feeding on the bait for a while and the poison builds up in their system. As they become weaker, they become easy prey for other animals. Animals such as dogs, cats and birds of prey that feed on the poisoned rodents are then poisoned themselves. If it doesn’t kill the predator outright, the poison remains in their system for quite some time – so there’s greater chance of the next rodenticide affected mouse or rat they consume finishing the job.

The other issue is one of tolerance – rats and mice are hardy animals that breed regularly during their short life spans. Some Warfarin resistant strains of rats and mice are have been observed, so more of the chemical needs to be used. Other animals haven’t developed this tolerance, so chances of survival should they consume a poisoned rodent become even slimmer.

I’d hate to think how much “collateral damage” is wreaked upon the environment each year by these poisons. To top it all off, rodenticides are deadly in aquatic environments too – so never flush old poison down the drain.

While chemical rodenticides such as the above do have their place at times, it’s a case of prevention is better than cure.

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The most important factor to consider when controlling Norway rats is population control. Killing individual rats is not enough; the idea is to control the entire population of rats in a given area, lest “new” rats move into treated areas as quickly as the “old” rats are exterminated.

Area-wide rat population control begins with taking actions to make an area less able to support a rat population, such as:

  • Reducing the amount of food and water available by implementing proper sanitation and waste management procedures. This may involve outreach to businesses and residents in which the importance of proper sanitation to effective rodent control is emphasized.
  • Reducing harborage by cleaning up refuse and debris in rat-infested areas.
  • Utilizing non-chemical control methods such as exclusion to keep rats from entering buildings and other sensitive areas. The National Park Service has an excellent manual for rodent exclusion, which can be downloaded here. (Adobe Acrobat Reader required.)
  • Continued monitoring to evaluate the ongoing effectiveness of the rodent control program.

Source: http://scarafaggio.us/ (free info about pest control and exterminating)

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Rodent Related Trivia

– Mice can leap up to 1 foot vertically and will jump against a vertical surface to use it as a launching pad to get extra height. A rat can jump up to 3 feet.

– Mice can produce up to 50 young a year.

– A mouse can become pregnant again within 2 days of having given birth to a litter.

– Warfarin is also used as a blood thinning medication for humans – in much smaller quantities of course.

– A mouse can squeeze through a space less than a quarter inch wide, rats only need a half inch (depending on the species)

– Rats memorize their environment by body and muscle movement

– A rat’s front teeth never stop growing, hence the need to continually gnaw

– A single rat creates 25,000 droppings in a year

Pests? Most definitely, but mice are just so darned cute and I admire their resilience and adaptability; I hate having to kill them. It’s a shame we can’t all live together in harmony.

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Rat Information

The principal indoor rat-sized pest in the Eastern part of the country are Old World (exotic) rats. The most common, rat-sized structural pests in the West, are native wood rats, squirrels, and chipmunks.

Both native and exotic rats quickly adapt to nearly all living environments provided them by humans (granaries, fields, sewers, attics, basements, etc.). Old World rats, similar to exotic mice, often live most of their lives inside buildings.

In the West, chipmunks, wood rats, some ground squirrels, and tree squirrels may nest inside buildings, attics, crawlspaces, chimneys, etc. (especially during winter), but usually feed outside and seldom enter occupied portions of a building.

Old World female rats become reproductively mature when about 3 months old and can produce an average of 20 surviving young per year. Native rat-size rodents are less productive than mice but females can usually raise 3 to 4 surviving young each year.

Rats eat the same general foods as do mice but, being larger animals, require about 1-ounce (2 tablespoons) of food and 2 to 1-ounce of water per day for survival. Like mice, a water supply is not as critical as food because most water comes from their food.

Old World rats are very agile and can leap 3-feet straight up or 4-feet horizontally. They can also climb the outside of a 3-inch diameter pipe, walk on wires between buildings, swim 1/2-mile of open water, tread water for days, swim up-current in sewer lines and through toilet traps, and survive a fall of more than 50-feet. Native rats (tree squirrels, wood rats, chipmunks, and some ground squirrels) are also very agile.

Rats have powerful teeth and are able to gnaw holes through concrete block, aluminum siding, adobe brick, wall board, plaster, wood, and various other durable materials. Usually, there must be an exposed edge to gnaw; smooth surfaces limit their ability to initiate holes.

Although rats are much larger animals than mice, they can squeeze through holes only ½-inch in diameter.

Old World rats usually range within about 100 to 150-feet of their nest. They may sometimes nest indoors and forage outside for food – or – live outside and forage indoors. Native rats have relatively large forage areas and can move long distances from an indoor nest site to a food source.

Outside Tips

–      Remove as much grass, weeds, and debris as possible from around buildings. These provide food sources and harborage sites for rodents.

–      If possible, maintain an 18-inch wide, vegetation-free zone around buildings. Continually clean up all outside and inside clutter/litter.

–      Trim the bottoms of hedges and other ground-hugging plants up from the ground to eliminate rodent harborage. Trim plants that touch or overhand buildings back 3 to 4-feet.

–      Promptly repair all water leaks.

–      Store firewood, lumber, rubbish, equipment, construction materials, and other items on pallets raised at least 18-inches off the ground and located at least 30 feet from buildings, walls, and fences.

–      It is better to place exterior lighting on poles out and away from structures and shine the light back onto buildings from a distance. This prevents the attraction of night-flying insects which can serve as a food source for rodents.

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Controlling Rodent populations: National Park Service Tips

–      Make a thorough inspection of the exterior and interior of a building. The main purpose of an inspection is to identify structural defects which allow rodents to enter buildings. Inspections also provide information on the species of rodent’s present, key shelter areas, locations where animals obtain food and water, and identify conditions around buildings favoring infestations. Those findings are used to set priorities for repairs needed to keep animals out of buildings and to recommend changes in conditions supporting rodent populations.

–      Effective exclusion. Rodent control in structures is based on one simple rule: rodents must be prevented from entering a building or a room. Excluding rodents by closing all possible holes where they can enter or leave a structure is always the most important measure against infestation.

–      Good sanitation practices that eliminate food, water, and shelter for rodents. Good sanitation removes essential resources (water, food and shelter) needed by rodents and limits the numbers of animals that can live in an area. Good sanitation is very important for controlling rodent populations, but even the best of sanitation measures will not prevent infestations where exclusion is not adequate.

–      Continually removing 85 to 95 percent of the rodents present capable of reproduction. Rodents mature quickly and produce large numbers of young. The numbers of animals present will not change much or may continually increase unless most of the breeding adults are removed.

–      Regularly checking for new rodent activity. Regular documented re-inspection (monitoring) of sites is important to determine if previous control efforts were effective; to find any newly opened holes animals could use; to watch for changes in sanitation and harborage conditions; and to determine if the numbers of animals present are increasing, decreasing, or unchanging. The importance of continual watchfulness is clear when it is known how rapidly rodent populations can increase and how difficult it is to control established infestations.

–      Cooperation between people. Rodent management must always be a team effort between building occupants (affected persons), maintenance workers (for repairs), and area managers(decision makers). It is urgent for all involved persons to be totally committed to and have a clear understanding of the program needs

–      Assign responsibilities. Assigning responsibilities to the people involved in the rodent management project is essential to success. Responsibilities with completion dates should be determined by the participants and put in writing. This ensures each team member is aware of what is being done and their responsibilities.

None of the above activities are difficult to do but when any of them are overlooked or not sufficiently stressed, rodent control is often unsuccessful.

Common failures in controlling rodent infestations in buildings are usually the result of one or more oversights:

–      Under-estimating the severity of a rodent infestation – either in regard to the numbers of animals present

–      Failing to find or satisfactorily closing holes used by animals to enter rooms or buildings.

–      Using too few traps, trapping stations, or improperly placing traps.

–      Failing to have “buy in” or cooperation of site occupants and management. Usually the result of failure to assign responsibilities in writing.

–      Failing to remove trapped rodents which become food for surviving animals.

–      Failing to secure garbage and other food supplies.

–      Placing too much reliance on poison bait as a means of control.

Mice are actually somewhat smaller than they appear and can squeeze their head through a

hole only about 1/4-inch in diameter, about the same size as a wooden pencil. After getting its head through a hole, a mouse has no trouble getting the rest of its body through.

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