While talking with an older friend I fish with, we got on the subject of muskrats. His dad and him used to trap them years ago and a place that is now all concrete and buildings is where they used to trap. He told me it was nothing to look out there and see endless rat houses. I remember a topic a while back about muskrats and the different opinions of why thier numbers are low. I really think thier worst enemy is us. When you see companies building in every direction and rural ditches being constantly straightened or tiled over, I wonder if there will even be a muskrat fifty years from now. Dale

Fortunately, we've seen no changes here. Dry summers seem to be the only contribution to a decline, but a normal, or wet summer, bounces them back. This observation is simply mine, in NW Ohio, encompassing the last 25 years.
My recently dug wetlands put in out back showed a handful of sign from muskrat last fall, and absolutely exploded over the course of spring and summmer. Ditches holding water on my way to work also show muddy runs.
Often, new complexes that shoot up around here are required to have some sort of water source or pond, either for asthetic appeal, or some other function. The 'rats seem to move right in then. I guess it's something.

You can see miles and miles of cattail swamps here in Minnesota,totally devoid of rats.We have the habitat, but we also have a very large Raptor population,which I believe is one of the major reasons for our rat decline.
Tom

My theory on any "so called" rat decline at least here in the North East is this. Its been one of the wettest years in history so many areas that didn't hold water years past are now holding water, thus allowing rats to spread out more into areas undiscovered yet. I have in previous wet years found rats in the middle of the woods where a depression about 15 yds wide by 20-30yds long held excess water only about 3ft deep at the most. This spot was found by accident and proved to be very productive for such a small area.

There's no natural rule specifying that only one thing may be at play. The reverse is often true - populations, particularly those of R-selected critters like muskrats, can suck up a few changes with little effect.

It's also worth noting that trends, by definition, are neither short-term nor localized.

Raptors certainly eat rats, but they're almost certainly not permanently driving populations on a continental scale.

Forget muskrats for a while. Say your car is running a little rough, so you take it to your mechanic and demand he replace the #3 spark plug. Never mind that you have no idea how cars actually work, or that you solicited the advice of a specialist, or that you could have fixed the problem yourself were it as simple as you postulated, or that you've never changed the filters and the muffler rusted off 40,000 miles ago; you simply won't be happy until he agrees it's that #3 plug and agrees to fix it for a couple bucks. Then sue him because your muffler is still rusted out.

Now back to rats. With a few notable exceptions, we've been driving this planet hard, ignoring the maintenance, and tossing our trash into the back seat, all the while proclaiming that simply funding this or that little problem will fix it all up. Ignore the whole anthropogenic climate change thing - hell, ignore atmospheric gasses entirely if that's what it takes to keep your hackles in place - and you're left with things like abnormally high levels of mercury in EVERY SINGLE FISH tested from AK to FL, abnormal estrogen levels in US waters, a whole lot of concrete, and simply how damned much of what you see out your window isn't native.

That is where the rats went, and where they'll continue to go as long as ignorance is a badge of pride in America.

(This thread got off track. I've edited it back to the divergent point. -- Hal)

I've only been trapping for 10 years and in that time we've never had what you would call a large number of rats compared to the stories I hear from long time trappers. It's interesting because considering what prolific breeders they are you would think they would be more stable. My guess for my area would be the explosion of coyotes and raptors the last 30+ years. The banning of DDT in the 70's and it's positive effect on hawks, owls and eagles certainly applies in my area. I don't think the it's been as much with development because of the overly regulated protection of any thing that could be considered anything close to a wet land. But when you're at the bottom of the food chain like a rat is, who knows?

Development won't hurt rats population? I once had a small marsh to trap that every year had anywhere from fifteen to twenty rat houses. This place was a blast to trap and although I never kept averages per house I would guess it was three or four rats per house average. The tributary ditch that provided the water for this marsh had the trees cut down on the high side and a bench was made with a dozer and then a excavator dredged this ditch. The marsh disappeared and ever since has been nothing but weeds. Thats also development!

Guess your states regualtions concerning anything wet are a little more liberal. We're pretty regulated with wet lands or ditches that control the flowage of water to and from wetlands.

Dated for search.