Bird disturbance – causes and impacts

Rebecca MoberlyPlanning & Advocacy Lead (Kent, Sussex and Surrey)

Birds and disturbance

• What do we mean by disturbance?• What activities disturb birds?• What are the impacts of disturbance?• Housing, access and disturbance

What do we mean by disturbance?

• Human activity that may influence a bird’s behaviour or survival

What activities cause disturbance?

• Site specific as to where and when they occur

• Difficult to generalise about activities

• Most common on estuaries: aircraft, baitdiggers, vehicles, boats, walkers and dogs

Impacts of disturbance

• Stress• Direct mortality• Avoidance of suitable habitat• Behavioural response• Change in food intake rate

Population consequence?

Interaction of factors

• Baie de Somme, Oystercatchers

• Disturbance influenced mortality only when cockle stocks low

A matter of choice

• By feeding turnstones and then disturbing them it has been shown that the birds that fly away 1st are those that are full…..

• Birds can react as they would to a predator & make choices according to risk

Examples

• Breeding Little Terns: birds avoid busy beaches, signage and wardening leads to increased success

• Breeding Ringed Plovers: avoid busy areas, trampling of nests, marked population consequence.

• Wintering geese & swans: avoid disturbed sites• Wintering waders: mortality in some circumstances

Links between housing, access and birds

• People visit the countryside and coast for a wide range of reasons. Visitors at sites will often be a complex mix of local residents, day trippers and tourists.

• How does housing relate to visitor numbers?

• What is the link between visitor numbers and impacts on bird populations?

When is access a problem?

• Access is important for well-being, conservation, education etc.

• In general, potential threat caused by:– Large groups– Faster moving– Accompanied by dogs– Erratic

• Adverse effect when survival or breeding success affected

• Responses site and species specific

Finally

• Disturbance and urban effects need to be considered in context with other threats

• Climate change may result in different birds present and different access patterns

• Difficult to define specific distances for urban development

• There may be existing impacts from which difficult to separate impacts of new housing