【Alight】 , 【Light】 , 【Land】 , 【Perch】 and 【Roost】 share the meaning to come to rest after or as if after a flight, a descent, or a fall.

【Alight】 suggests previous controlled or gentle movement through the air or open space (as of a flying bird or a floating snowflake)

• skylarks 【alight】 on the ground

【Light】 , sometimes the equivalent of 【alight】 , more often presupposes a falling or jumping than flying or floating, and sometimes merely a wandering or roving.

• he sprang from the roof and lighted on his feet
• we came smack down on the animal tent; when we lit the tent began to tear
  —Sandburg

【Land】 applies to a boat coming to 【land】 or an airplane grounding. Though often used interchangeably with 【light】 , it may connote arrival at a destination and sometimes driving force or power.

• the airplane landed in a swamp
• he fell headlong and landed on his face
• his blow landed in the spot he aimed at
• he has landedwhere he hoped, in an executive position

【Perch】 and 【roost】 basically imply alighting of birds, but 【perch】 suggests settling on something elevated to which the claws may cling (as to a pole, bar, or twig) and 【roost】 , the settling for rest or sleep, especially by domestic fowls, on the perches and in the shelters prepared for them. So 【perch】 often implies elevation of position and tenuousness of grasp or hold.

• twenty or more [rooks] perched aloft, cawing and conversing comfortably
  —Jefferies
• a lofty perpendicular cliff . . . with a castle . . . perched on the distant top
  —Lucas

【Roost】 , when used of persons, often suggests a position like that of roosting fowls

• boys roosting on the rail of a fence