If you have the time before your trip, order up the birth certificates. Officially, if you are an American entering Canada from the US for a visit, you need one of the following: a valid US passport, or an original US birth certificate plus photo ID, or an original US naturalization certificate plus photo ID. A driver’s licence or a voter’s card are not acceptable as ID. Note that particular attention is given to ensure that children being brought into the country are not being abducted, so have similar ID for them.
If you have been convicted for any of the following, you and nor admissible to Canada: shoplifting, theft, assault, dangerous driving, unauthorized possession of a firearm, possession of illegal substances, and similar minor offences, or indictable offences such as assault with a deadly weapon, manslaughter, and the like, or driving while intoxicated. If you or your ducks fall into any one of these, you might consider applying for a minister’s permit.
Unofficially, if you do not have the time to order up your documents, just show up at the border with your driver’s licence and odds are you will be passed through unless your ducklings are restless and start complaining. There are rules, and then there are rules, and most border officials have a strong dose of common sense, so the odds are the passport/birth certificate rule will not be enforced provided that its is obvious that you are a family on vacation. (The same goes for the speed limits, which on Highway 401 are posted at 100 kph, but which are ignored by everyone who usually zip along at 120 kph and only occasionally get nabbed).
The odds of being stopped and turned back at the border are very slim. Odds are that your identity will not be questioned too seriously, and if you are questioned, it will be more to ensure that you are not snatching children or bringing anything nasty into Canada (whatever you do, do not try to bring a handgun into Canada). Just make sure that your ducklings know to identify you as their mama. In any event, since the drive from Detroit to Niagara Falls is lovely on the US side, don’t be bothered if you get turned back for not having enough paperwork. Just tell the kids that Sandusky has some huge coasters waiting for them.
On the Canadian side, Highway 401 is as flat and boring as anything you would come across in Kansas (I do not exaggerate), but if you have the time, the trip along Highway 3 along the north shore of Lake Erie is quite delightful, with the birds and beaches of Point Pelee http://parkscanada.pch.gc.ca/parks/ontario/point_pelee/Point_pelee_e.htm being well worth visiting. Along the way small fishing villages such as Port Stanley http://www.port-stanley.com/ offer nice spots for lunch and a dip (Port Stanley’s main beach is on the other side of the river from the main village).
I used to live down that way and taught sea kayaking on Erie and Huron, so there is a special place in my hear for Erie’s beaches. The vegetation is Carolinian, which is very rare for Canada – much more like what one gets on the other side of the border, there are more birds that you can shake a stick at (particularly during the spring migrations), and the water is warm, warm, warm (as opposed to the ice cold water of Superior where I am now paddling).
Similarly, if you are doing the tourist thing, Niagara Falls Ontario http://www.city.niagarafalls.on.ca/ is much more fun than Niagara Falls New York, for it has a better view of the falls and has lots of horridly tacky attractions that kids love (and if you want to enjoy some much more refined time, drop downstream to Niagara on the Lake in Ontario http://www.niagaraonthelake.com/ which is a truly lovely town in which to wander).
Have fun, and don’t forget sun screen for the entire family a the beaches and KY for the entire family for the probe at the border.