<P> This species usually breeds in colonies , in trees close to lakes or other wetlands . Adults generally return to the colony site after winter from December ( in warmer climes such as California and Florida ) to March ( in cooler areas such as Canada ) . Usually , colonies include only great blue herons , though sometimes they nest alongside other species of herons . These groups are called a heronry ( a more specific term than `` rookery '' ) . The size of these colonies may be large , ranging between five and 500 nests per colony , with an average around 160 nests per colony . A heronry is usually relatively close , usually within 4 to 5 km ( 2.5 to 3.1 mi ) , to ideal feeding spots . Heronry sites are usually difficult to reach on foot ( e.g. , islands , trees in swamps , high branches , etc . ) to protect from potential mammalian predators . Trees of any type are used when available . When not , herons may nest on the ground , sagebrush , cacti , channel markers , artificial platforms , beaver mounds , and duck blinds . Other waterbirds ( especially smaller herons ) and , occasionally , even fish and mammal - eating raptors may nest amongst colonies . </P>
<P> This species usually breeds in colonies , in trees close to lakes or other wetlands . Adults generally return to the colony site after winter from December ( in warmer climes such as California and Florida ) to March ( in cooler areas such as Canada ) . Usually , colonies include only great blue herons , though sometimes they nest alongside other species of herons . These groups are called a heronry ( a more specific term than `` rookery '' ) . The size of these colonies may be large , ranging between five and 500 nests per colony , with an average around 160 nests per colony . A heronry is usually relatively close , usually within 4 to 5 km ( 2.5 to 3.1 mi ) , to ideal feeding spots . Heronry sites are usually difficult to reach on foot ( e.g. , islands , trees in swamps , high branches , etc . ) to protect from potential mammalian predators . Trees of any type are used when available . When not , herons may nest on the ground , sagebrush , cacti , channel markers , artificial platforms , beaver mounds , and duck blinds . Other waterbirds ( especially smaller herons ) and , occasionally , even fish and mammal - eating raptors may nest amongst colonies . </P>
what is a group of blue herons called
what is a group of blue herons called
heronry
heronry