Table 1. Summary of predictions (first two rows) to distinguish whether monarchs arriving in northern portion of the breeding range adopt a single sweep (SS) or successive brood (SB) strategy.

Natal Origin based on Stable Isotopes1	Great Lakes (GL)		Central (CE)		Gulf Coast (GC)
Year Born based on Wing Wear2	Previous	Current	Previous	Current	N/A2	N/A2
Inferred Strategy	SS	SS/SB3	SS	SB	SB

Notes:

¹See Figure 1 for information on stable-hydrogen isotope values between regions and Methods for information on assignment tests.

²Individuals with wing wear scores between 1–3 were considered to have been born in the sampling year while individuals with wing wear scores of 4 or 5 were considered to have been born the previous year (see Methods for details). The only exception to this is for individuals that were assigned to the GC region. In this case, all individuals must have been born the sampling year regardless of wing wear because it is unlikely that GC monarchs overwinter in Mexico because milkweed does not grow in the Gulf Coast during late summer when the migratory generation is produced (see Discussion for details).

³Monarchs born in the GL region in the year they were sampled could be either the offspring from monarchs migrating north from over wintering sites in Mexico (SS) or from monarchs that were born the GC or CE regions the same year (SB).