When last we visited our Broad Bean, it was barely poking its head out of the mulch and looked pretty much like a wad of chewing gum. As you can see, it's come a long way in the past week.
If you look closely at the photo, you'll notice a blurry cross-hatching in the foreground. That's the bird netting with which the planting bed is covered.
Whenever we plant seeds directly in the planting bed, it's worth assuming that the birds will be after them as soon as they sprout. A number of different birds will go after and eat the seedlings; from a bird perspective, this makes sense: as human aficionados of sprouts will tell you, seed sprouts are packed full of nutrition; the birds will gobble them right down.
There are some seedlings that don't seem to appeal to avian tastes, but that doesn't stop the birds from trying them out. Kind of like a person who goes through a box of chocolates, tasting and rejecting each one, the birds will go right down the row, pulling out each seedling and casting the unpalatable ones to the side. Some birds, such as the Curved-Bill Thrasher seem less interested in the seedlings themselves,and more interested in digging around each of them in search of insects; the result, however, is the same.
In this particular bed, the Broad Bean plants are probably now large enough that the netting could be removed without fear of avian predation, but since this same bed also has sprouting carrots, beets and cilantro, I'll leave the netting on for awhile yet.
Interestingly, the bird behavior isn't the same every year. Depending on the weather, availability of other food sources, migration patterns, and other factors, there may be years when you can leave a seed bed uncovered and have not the slightest damage. But since that's unpredictable, make it a habit to net your seed beds as a matter of course.