It’s not a pretty harbinger of spring, but look for black vultures kettling with our local turkey vultures, both of which are here to help with nature’s spring cleaning. Kettling is a behavior where migratory birds — primarily raptors like hawks and vultures—gather in large numbers to soar in a tight, rising spiral on a thermal (column of warm, rising air). This swirling, upward movement mimics steam rising from a boiling pot, conserving the birds’ energy during migration. This is often seen mid-morning during spring and autumn migration seasons. BARRY REED/SPECIAL TO THE TIMES NEWS