Okay, so there will be a lot of them... but what harm would they actually do in a chicken coop? Genuine question.
First they will double or even triple the cost of feeding your chickens if you allow the colony to develop and they will. Let's follow the reproduction/life cycle of a single female mouse.
Sexually mature and breeding at six to eight weeks from being born.
After breeding she delivers the pups in 19 to 21 days. Up to 12 pups are born per litter.
Assume half are female and assume all survive.
One female leads to six breeding age females in nine weeks. Now you have seven breeders producing in three weeks another 42 female pups.
Another nine weeks you could have 294 breeding age females plus the 294 males.
Feed per day per adult mouse, two to six tablespoons per day. Lets say 4 is average.
294 + 294, just the new mice, ignoring the first male and female and the second generation of 12 mice, 588 x 4 tablespoons = 2,352 tablespoons of feed needed.
Tablespoons per gallon of feed, 256 or over 9 gallons of food PER DAY.
Now some won't survive, infant mortality, predators, whatever. But, the potential colony size in just 4.5 months is huge and people plagued by mice that have bought my feeder report their feed bill cost going down three and even four times.
Next and even more important. Disease and parasites. There is a site called chicken feeder reviews that has some pages on chicken information and one of the pages is on disease and pests, where you will find a pretty complete complete list of parasites and diseases. The info there will scare the putin out of you. Chickens skate on thin ice at all stages of their lives which is why commercial flocks spend a fortune on bio protections including preventing wild birds and rodents from hanging around. You do NOT want rodents coming into your flock if you care about your hens.
Next but not last, predators. Rodents pee when they walk. To mark territory, to communicate, and as a road map so to speak. It signals they are ready to reproduce and even if a male rat has babies to protect and feed.
And they pee a lot, 5ml per 100 grams of mice, call average weight 25 to 40 grams, roughly ten to twenty mice per pound, roughly the 588 adult mice would put out a third of a gallon of pee each day.
Mouse pee is dangerous to humans, it spreads horrible diseases. But the mouse pee is also visible in UV light which some hawks and falcons see as a bright yellow trail with the most recent urine shining the brightest.
So now you have a huge scent trails leading directly to your coop for mammalian predators like foxes, coyotes, and cats plus a bright yellow road map leading directly to your coop in daylight and in the dark for hawks, falcons, and owls.
Then mice eat eggs and will kill chicks.
Mice also attract snakes and.... rats. Rats prey on mice and both emit a different distinct odor, so the mice will attract the rats and almost always the rats will drive the mice away or kill them.
Now instead of having mice at ten to twenty per pound, you have up to one pound rats that reproduce just as quickly and eat ten times more per day.
Mice and rats also eat electrical wiring. My mom had two cars totaled from mice eating the wiring. Elderly, didn't drive but a few times a month. Plus eating the wiring in your house.
Thank you for the thorough reply!
