This critter might have the highest failure rate for predators.
Good ol’ Lester is pretty invested there, ain’t he?
What about constrictor snakes (e.g. boas, pythons, anacondas)? When they’re ready to eat they can’t afford to waste energy on misses, so they mostly wait until a sure thing comes along. That has to result in a pretty high success rate.
Oh great, I have a huge stack of reports to write, and I spent nearly two hours poking around on that honey badger site. Yikes! My kill rate for reports is stalled at 10%.
There are birds that can catch fish but also harass other birds and make them regurgitate the fish they caught. Maybe they could be said to have a high ratio because they make others do the predation work and even some of the digestion work. Five kills in zero attempts! Hm, maybe that doesn’t count.
Pit vipers. Like the aforementioned constrictors they are ambush predators that can wait for perfect conditions. Having worked with many of them over several years I can say that in a captive environment they miss extremely rarely. I would confidently place the attempt/kill rate in the high 90’s at a minimum. If things aren’t right they simply don’t strike.
I just thought I’d nominate web-weaving spiders. As a kid, I spent many an afternoon catching flying insects and releasing them into webs. Very occasionally, the spider ran over to wrap something up and had it fight loose, but probably 95% of the time anything caught on the web was toast.
On the other hand, anything eating clams and urchins will still probably beat that record.
Also, the “besides us” qualification of the original question seems pointless to me. Slaughter houses have a pretty good kill rate, but people who are actually hunting or fishing for prey aren’t much better than the lions.
if it’s mammal vs. reptile, i’d say the mongoose has a close-to-100% kill rate. if it’s mammal vs. mammal, nothing beats a hungry cat pouncing on a mouse. some cats that aren’t that hungry playfully pounce on rats but let them go.