The numbers of chipmunks reported in
South North, Central and South Frontenac are far lower than previous years.
Estimates are that numbers are down 80-90%.
Queen's University's Mark Conboy suggests that a "non-food cause" is to blame. Apparently a similar die-off occurred north of Toronto last year.
Acorn and beech mast production was poor in 2011, but even large numbers of chipmunks that lived near bird feeders have not survived the winter.
There are three likely causes: a disease, or the extremely warm winter of 2011-12, or extreme predation.
a) One excellent argument against the disease scenario is that such a wide area of the Frontenacs have seen a 90% die-off. Chipmunks have a small 100meter territory, so any disease would need a vector - perhaps the deer tick, which has been increasing in the Frontenacs - along with lyme disease.
b) The winter warmth has been shown to cause die-off in chipmunks, especially, because their hiberation is severely curtailled by the warmth. When not hibernating they require a lot more food. And "wild" chipmunks would be unable to find new (unstored) food in the middle of winter. One excellent argument against this theory is that even "tame" chipmunks that have stored a lot of gleaned bird seed have also died off.
c) Many reports have indicated higher numbers of hawks, eagles, fox, red squirrels, etc. But there is no obvious commonality so far. Of course, if the chipmunks are weak (from disease or starvation) then predators will be more successful.
The speculation continues. If carcasses are available then an autopsy may deliver some answers.
I have mapped the reports that I've received. It is colour-keyed. Green means no difference from 2011, Orange is a very noticable decline. And Red is no chipmunks seen.
The number in the circle indicates how many reports are from the same area.
Here is the high resolution map: http://sfnec.org/sites/sfnec.org/pictures/FrontenacChipmunkReports.png
And here is the low resolution version for dial-up users: http://sfnec.org/sites/sfnec.org/pictures/FrontenacChipmunkReportsSmall.png
June 20 Update: The next generation of chipmunks has started to re-populate the empty areas. Be careful not to run over the new arrivals.
Sep 3 Update: While the chipmunks have spread out into empty areas their population density remains low and, interestingly, the chipmunks are very quiet. Gone/rare is their normal bahaviour of sitting up high and "scolding" the world for minutes on end. Also, when surprised they slink away without a "complaining" "chip" sound.
Feb 24, 2013 Update: A healthy looking chipmunk showed up today.