The phrase "a large flock of" is correct and usable in written English.
It can be used when describing a significant number of birds or animals gathered together.
Example: "As we walked through the park, we spotted a large flock of geese flying overhead."
Alternatives: "a big group of" or "a sizable gathering of".
Upon takeoff, the plane flew into a large flock of birds.
He's in New York for the World Science Festival, along with a large flock of Nobel laureates and other luminaries.
Syncrude said this was the first time in its 30 years that a large flock of birds had landed on a tailings pond.
He had a large flock of the long-legged birds that he kept in his backyard but was looking to get rid of and loaded onto a trailer.
Walking down towards the shore, I could see hundreds of birds balanced nervously on the skim of ice forming on the fringes of the lake, including a large flock of bar-headed geese, Anser indicus.
Closer to home, she once rescued a songbird, a lucky survivor, that had strayed into her office when a large flock of migrating warblers crashed into the Empire State Building.
Meanwhile for turkeys and broiler chickens, which are floor-reared (ie not kept in cages), the use of water-based foam similar to that used by firefighters is the most effective way to euthanize a large flock in a short period of time, says Beth Carlson, North Dakota's deputy state veterinarian.
As we tour the farm, past the pretty pig sheds, the large flock of Christmas geese, and the room where children help sort the free-range eggs, its walls covered in kids' paintings of their favourite animals, Stephens shares his farming philosophy: "So many people are fed up with the blandness of food," he says.
She tells me she attended a peace rally and watched as a small group of bearded protesters passed by, accompanied by a much larger flock of journalists.
Large flocks of birds flying in a tight group are one of the most spectacular shows that nature has on offer.
The use of city buildings for roosts by large flocks of starlings and blackbirds is also a problem, as is the nesting of albatrosses on airplane runways on Pacific islands.
