Bird

Cliff Swallow

Petrochelidon pyrrhonota

Low Risk

Biology

Petrochelidon pyrrhonota is a compact swallow with a square tail, pale forehead, dark rusty throat, blue crown, and buff rump. It is famous for building gourd-shaped mud nests in dense colonies on cliffs and, increasingly, on buildings and bridges.

Behaviour

Cliff swallows are colonial nesters; dozens or hundreds of mud gourds may appear under building overhangs, eaves, and bridge abutments. They feed on flying insects and migrate in large flocks.

Habits

Colonies produce significant accumulations of mud, droppings, feathers, and parasites on walls, walkways, and vehicles below. Heavy infestations can accelerate corrosion, clog drains, and create unsanitary conditions in public areas.

Control methods

1Exclude with netting or hardware cloth before colonies arrive in spring
2Remove unoccupied nests during the non-breeding window
3Treat surfaces to make mud adherence difficult
4Clean droppings and debris with pressure washing and PPE
5Seal overhang gaps and architectural cavities that attract nesting
6Follow migratory-bird protections; obtain permits where required

Tailored to Cliff Swallow

IPM Procedure Checklist

View full procedure

Step 1

Inspection

Identify roosting, loafing and nesting sites
Document droppings, feathers and damage to structure
Note food and water sources attracting birds

Step 2

Identification

Confirm Cliff Swallow (Petrochelidon pyrrhonota) — not a look-alike
Note life stage and risk level: Low
Capture clear photos and samples for the record

Step 3

Action Thresholds

Tolerate low-level activity outside sensitive zones
Act if activity moves indoors or near food
Review threshold seasonally with the client

Step 4

Prevention

Install spikes, netting or shock track on ledges
Remove standing water and accessible food
Close openings to attics, vents and signage voids

Step 5

Control Methods

Exclude with netting or hardware cloth before colonies arrive in spring
Remove unoccupied nests during the non-breeding window
Treat surfaces to make mud adherence difficult
Clean droppings and debris with pressure washing and PPE

Step 6

Monitoring & Evaluation

Service monitors on schedule and trend captures
Re-inspect for Cliff Swallow activity at follow-up
Adjust tactics based on data; report findings to client