Something is pulling out my sprouts

Hi Everyone,
I am new to SFG and I recently planted some salad mix's and bak choy.

It sprouted and I do see leaves.

Today I went to check on my garden I saw some of the salad mix sprouts roots came out of the soil and some leaf fell apart from the root. The bak choy leaves seems like something is eating it or it falls apart.
I don't know if its bugs or some creature eating the leaves and pulling out the roots, weather, or it is doing it by itself.
Can someone help give me some advice on what to do? Do I cover the SFG? Spray something? More water?

Thanks for your help!

Mice are the worst enemies with new seedlings. They like to eat the tops out and leave a stem showing and sometimes they accidentally pull up the little seedlings while they
are having a mid night snack.
It would help a lot if you had a screen cage to put over the new seedlings until they get bigger or something similar.

Hi Carolyn,
Thanks for the tip and advice.
After searching around on google, I think it was attacked by birds.

When I saw all of this happening, I came on here to post my questions and do some research. About 15 minutes later I went back outside to cut cardboard to lay it on top of the boxes temporarily so that I can build a cage tonight, my bak choy plant is GONE! I looked up around my backyard and I saw several little birds in my neighbors tree(maybe a good 10). I am assuming it is the birds, so after that I quickly cut the cardboard and layed it on top of my SFG.
Since I don't like wasting time, I went to home depot right after.
Picked up the 48" by 25 ft. chicken wire fence 1" holes, 4 4 feet untreated wood one inch by two inch, and a box of course threaded drywall screws(they didn't have the deck screws) total came out around $30. I also had the zip ties and tools I needed at home so I didn't have to buy it. It took me an hour to find the materials and have the wood cut in half.

Took me 2 hours to put the cage together and it looks exactly like the one in SFG book. I made the cage a little taller just in case the plants would grow up to 3 feet.

Now the cage is resting on my SFG. I also hung a cd in the middle of the cage just for another layer of protection.

This is an all new experience for me and I learned a lot from it. I just hope now that the cage solves that problem.

Will let you guys know if the cage helped.

Let me know if you guys don't think it is the birds. Maybe it's something else and I don't see it. But the bak choy missing within 15 minutes to me must be the birds. I don't know though.

Any thoughts or comments would be great.