you will learn more than most PhDs by trapping and observing.....oh the line - correlation does not equal causation brings me back to horrid memories of biometry

Enjoy being outdoors and watching the Lords creation adapt and change. We definitely impact nature in mighty ways and I personally have issues with top former herbicide companies running our USDA. Worked too long for agencies to trust them when money is involved - money is always involved. Most corn crops are pounded with fertilizers, herbicides, insecticides and often fungicides. If only manure is being used - it would surprise me.

Around here about the only place you find muskrats in any numbers is in neighborhood ponds that all the big number neighborhoods are built around and all those fancy houses and lawns are treated heavily with everything under the sun to make them green and lush

I always assumed the same as Eric's findings. The creeks I trapped as a kid had loads of rats in them in the late 70's to the mid 80's. After that, populations went in the crapper. The only thing that made sense was chemicals used on crop ground. Hardly a rat anywhere on the creeks I trapped as a kid today.

I reckon, those urbanites aren't using much Roundup on their lawns.

We have as much agricultural spray up here as anywhere. When we have water we have rats, its that simple. Probably several factors leading to their decline.

interesting . . thanks for sharing

52Carl, which is specifically why I said linked and not caused by. I doubt anyone has scientifically studied or funded research into ALL the possible contributing factors beyond NOT being AG chems. Most of the research done to “ prove” safety are funded by the chem corps so they needs to be reviewed very judiciously. The current Neonics have been incidentally found in over 2/3 of MN deer being tested for CWD around the whole state. The effects are yet to be learned. But how wide spread might a buildup be? State bee keepers have won a lawsuit over it here. I am opened to true unbiased facts

My area stays pretty constant-slim to none. They are only by products of a mink and coon line here. You would be considered crazy to try to target them. What I always wondered is what happened when an area only giving up 0-3 rats for years gives up 3-6? Maybe we should ask whats bringing them back?

I'm not sure I buy the "chemicals used in farming" conclusion.

Reason being, in the Dakotas, which is essentially all farm ground, all you need is water and there will be rats galore.

That is some interesting info I commend you for taking your time to document some info and see what might happen over time I was a volunteer for a local Pheasants Forever chapter in south east PA for about 25 years from the1990's to 2018 The pheasant and the muskrat has been on the same population decline during that time As a 12 year old beginning bird hunter and rat trapper I could not have foreseen what has become of both of them But on the other hand coyotes are numerous throughout PA and in many places the white tail deer are regarded as pest Mother Nature is always changing

I own some of the same ground now that I trapped when a boy, a ditch creek runs to the river through it. Not one rat in it all winter, and mink droppings were in a pile on the culverts as a boy, now none. Did I kill mink when I put mouse poison in my deer blind 12 foot off the ground, probably, because it was completely eaten and my cushions were still all chewed up. I will try some dryer sheets from now on, don't want the dead mice to be killing other critters. But the lack of mink is not just in the field by me, lots less than the 70s.

Who do you suppose originally "linked" frog mutations to pesticides? Likely not friends of ours, to say the least.

Here I think chemicals too. Plus the creeks act different now than they did before all of the fields were tiled. Less water in the creeks, the fields all drain off faster. Plus there is less habitat as far as brush on the creek banks.

Spray fields, less water, less debris... not good for rats. I wonder if the minnow and crawfish population fluctuated with the rats? That would be an interesting line graph.