okay so that “would you rather fight one horse-sized duck or 100 duck-sized horses?” thing has been bothering me because, based on what I know of ducks, I don’t think those numbers would actually be in any way equivalent.

if you assume the duck in question is a mallard (a reasonable assumption given that the mallard is probably the most well-known and widespread duck species, and the wild ancestor of the majority of our domestic ducks), its average weight would be 35.3-45.9 oz (according to the Cornell Lab of Ornithology). If you take the mean of that you get 40.6 oz. By the same method I got an average (mean) length of 22.65 in, and, with some approximating, an average surface area of 575 square inches.

As for the horse, I chose a thoroughbred more-or-less at random (my rationale: a) they are a type of horse everyone has heard of and b) there is a great deal of info about them available to use in my calculations). The internet tells me (from various sources about breed standards), that thoroughbred horses stand at an average of 16 hands (64 in) and weigh an average of 1,100 lbs (17,600 oz), and are probably about 8 ft long (96 in). If you assume they are also roughly cylindrical, which is what I did with the duck, you get an approximate surface area of 25,736 square inches.

NOW TO COMPARE: If we assume ‘size’ to mean ‘weight,’ then horse : duck is not 1 : 100; it would take about 433 ducks to equal one horse. If you go by surface area, it would take about 45 ducks (because, as you might expect, horses are much denser than ducks). 

So “one horse-sized duck,” going by length, may be eight feet long, but it will only weigh about 11 pounds– that is if it was scaled up without changing anything else anatomically; swans are about 5 feet long and 25-30 pounds, but they’re more dense than mallards. (HOWEVER if your “one horse-sized duck” is going to weigh 1100 pounds, it is going to be a 830 foot long duck. I’m gonna go out on a limb and assume that’s NOT what people mean when they ask this question.) 

So how many duck-sized horses would really equal one horse-sized duck? If we use our eight-foot-long, 11 lb duck…… god I don’t know, I’m Very Bad at math, but I’m pretty sure the answer isn’t “100.” Someone who can do mathematics, please advise.