Wildlife : Habitat

The beacon Hill Park colony is largest colony on Vancouver Island!

The habitat requirements for nesting herons are somewhat general. They require a mature woodlot as they usually nest 15 meters above ground and it needs to be located within 3 kilometers of foraging sites. Alder trees seem to be a favorite type of tree, but they will nest in many different types of tree.

Some herons will abandon their colonies as a result of nearby human activity and from depredations of eggs, chicks and adult herons by eagles.

Eight out of ten herons on the coast live around the Strait of Georgia. This is also where two thirds of BC’s human population and three quarters of its labour force lives. Some herons are very susceptible to human disturbance during the nesting period and this can have a negative effect on nesting success. In the lower Fraser River Valley between 1981 and 1986 for every 1,000 increase in human population 28 hectares (ha) of rural land were converted into urban use (Moore,1990). This population growth impacted on heron habitat and further impacts are expected given the Georgia Basin population is projected to about double in the next 20 years. Herons are also affected by the food they eat. Contaminants now found in their tissues can be traced to growth in agriculture, manufacturing and forest industries, and urban developments.

Herons are also susceptible to disturbance from Bald Eagles that prey on chicks and adults in the colonies. A nesting heron study conducted in 1999 in the Georgia Basin concluded that Bald Eagles targeting heron eggs or young were responsible for the abandonment of 13 of 31 colonies (Vennesland, 2000). However, humans might have been ultimately responsible by creating a fragmented landscape that allowed eagles easy access to herons and their nests. Bald Eagle numbers on the south coast of British Columbia have gone up significantly. Scientists speculate the increase might be a delayed response to the banning of certain chemicals such as DDT that previously had affected their breeding success.