How do you tell if your eggs are fertile?

[Duck_life]

I'm looking to hatch ducks in spring, but I'd like to know if my drake is mating her. The breeds are: Mallard hen (She's a runt so she's very small) And a Pekin drake. She tries to get him to mate her but he never does, at least, not what I can tell from. I found this article and found it interesting, but not sure if it works. https://www.selfsufficientculture.c...gs-are-fertile-or-not-quail-chicken-duck.533/. I tried the trick and it was the apparent "fertile" I don't have an incubator so I can't try to incubate some eggs and see if they develop. The eggs are going to some family members so I'm trying to resist checking for the bulls eye in the egg, well, if it ihas that. So is there any other way to tell if they're fertile?

 

[SueT]

It's good to be checking yolks for fertile bullseye all along, as you use the eggs, so you know you have consistent fertility. By spring, there will be no doubt. I check every egg I eat, just out of habit/curiosity. I rarely see our rooster mating the hens, yet had fertile eggs that hatched, so they are doing it out of my sight.

 

[Duck_life]

It's good to be checking yolks for fertile bullseye all along, as you use the eggs, so you know you have consistent fertility. By spring, there will be no doubt. I check every egg I eat, just out of habit/curiosity. I rarely see our rooster mating the hens, yet had fertile eggs that hatched, so they are doing it out of my sight.
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My roosters been pretty hormonal lately, I've been checking his hens for fertile eggs and most of them are fertile, but I never had caught my pekin mating her. He prefers staying with my disabled duck. Guess I'll just have to crack an egg and check. Thanks you.