Influence of habitat configuration on breeding-season female monarch butterfly (Danaus plexippus) movement and space use in north-central USA agroecosystem landscapes

The eastern North American monarch butterfly is at risk of quasi-extinction due, in part, to the loss of breeding habitat in agricultural landscapes of the USA Midwest. Because adult females are not patch residents, egg abundance and distribution across the landscape is a function of their perceptual range to plant resources, flight directionality, and flight step lengths. Improved understanding of movement behavior in complex landscapes is needed to support conservation plans that create functional connectivity. Field-captured, radio-tagged females (n=114) were tracked in a 64-ha area containing restored prairies, grass-dominated fields, and crop fields in Floyd County, Iowa, USA and two 1,000 m linear north-south sections (~ 50 ha) of grass-dominated roadside along secondary roads with different proximity to prairie habitat in rural Story County, Iowa. Monarchs were released in areas with a high-density, low-density, and zero density of resources, as well as on the habitat edge between high and zero-density habitats. Monarchs were tracked for 3,600 sec and were observed moving among habitat classes and performing up-wind search behavior. Monarchs successfully located resources, with some flying over 500 m to find high-density areas. This study provides evidence that the monarch perceptual distance is > 100 m. Step lengths were mostly < 50 m and turn angles were directional. Large displacement steps (≥ 50 m) occurred in approximately half of the monarchs and may indicate the initiation of a long-range search for suitable habitats. Establishing habitat patches 50 m apart in agricultural landscapes may facilitate efficient monarch movement.