Figure 5.

Figure 5. Qualitative estimate of the saguaro pollen load carried by each dove obtained by swabbing the bill, crown, cheeks, and chin of each bird with a clean strip of transparent adhesive tape.  The abundance of pollen grains in each sample was ranked using a qualitative score (0 = no pollen grains; 1 = less than 25; 2 = from 25 to 50 pollen grains; 3 = from 50 - 1-pollen grains; and 4 = more than 100 pollen grains).  Only pollen from the saguaro was found on white-winged doves.  Pollen loads indicated that birds visited saguaro flowers intensely from the beginning of May until the first week of June.  Indeed, all birds collected in may and the first week of June had saguaro pollen in their bills and head feathers.  Pollen loads indicated that some individuals continued to visit saguaro flowers throughout the summer even when floral abundance was low.  Points are means (N ranges from 6 to 10 birds) and bars are standard errors.