The crows most likely found a banquet of grubs in your lawn. It happens. I don't know how they got there, but there are several products you can apply to get rid of them. Frankly, I just let the crows, starlings in my case, have a go and take their fill. Those products kill indiscriminately.

We had this problem a couple of years back and we just let the birds get on with it. yes they pulled up some of the grass but it recovered. I am expecting similar next year as we have had a lot of crane-flies this year and they will have laid their eggs in the turf. [locally called Daddy long legs, not the spider ones. gosh I hate common names!]

They really don't do any real damage - they just want those darn bugs. Then my gardener comes with his mower and it's like nothing ever happened. The grass looks fresh and healthy.

Thanks, guys. I was caught in two minds to whether or not to try to treat the lawn, but was not sure that was even possible. I suppose that the birds will remove whatever bugs are inevitably doing harm to the roots of the lawn, so I suppose I will end up leaving them..... other than chasing them when I see them.

If you really want to get rid now is the time to water with nematodes, but it sounds as though the crows are doing a good job on their own. Look at it this way - the crows are spiking the lawn for you and saving yo a job???