Sure. Basically because they can. Rats spend a lot of time foraging for food, and eggs are good nutritional value.
Certain types of birds do lay eggs on the ground.
Penguins
No. Hawks always provide deep nesting for their eggs and never in the crook of a tree that low to the ground. What you are probably observing is starling or grackle eggs. These birds like to lay eggs in the "nests" of other birds so the do not have to care for the eggs themselves.
they sit on their eggs about the same amount other birds do and they do not bury their heads in the ground.
Dodo birds no longer lay eggs, as they are an extinct species.
Kildeer for one. herring gull for two.
Or: How much ground would a ground hog hog if a ground hog would hog ground?
It keeps the eggs and chicks away from ground dwelling predators.
Probably none. Birds generally build their own nests. It makes them feel safe.
I am not sure about the amount of eggs.... most likely 4-5 eggs, but some birds lay eggs in nests of other birds when they have hatched their eggs and are done raising their chicks.
Laying eggs on the ground can lead to fewer partridge chicks due to increased predation risks and environmental factors. Ground-nesting birds are more vulnerable to predators, such as mammals and birds of prey, which can easily access the eggs and chicks. Additionally, eggs laid on the ground may be more susceptible to adverse weather conditions and habitat disturbances, further decreasing the likelihood of successful hatching and chick survival.
Birds lay eggs because, they need to make babies so there are more animals of their type. Like Dinosaurs they lay eggs too. And many differant animals do as well. Hope that answers your question!