Brownsville Bluff Scientific and Natural Area, in Houston County, was designated on January 19, 2016, to protect habitat for the milk snake and the state threatened western ratsnake. Neither snake is poisonous. The site consists of 286 acres bedrock bluff covered with windblown sediment. The 39-acre south section is a wildlife sanctuary that is closed to the public. The eastern-facing slopes are moderately steep to very steep. They have a mature, moderately moist forest of sugar maple, basswood, ironwood, northern red oak, and white oak. The west-facing slopes are less steep. They have a dry to moderately moist mature forest of bur oak, northern pin oak, northern red oak, and paper birch, with some shagbark hickory, white oak, and black walnut. At the top of the bluff there is a prairie that has been used as an agricultural field. It will be restored to prairie and savanna.
An access road leads from the parking area (walk around the gate) 0.67 miles to the top of the bluff. A footpath follows the cleared fields on the bluff top to the northern boundary. Another footpath leads east from there to a spectacular overlook at the northeast corner of the SNA, a dizzying 400 feet above the road below.
Designated on June 12, 2017, Lawrence Creek SNA is one of the newest Scientific and Natural Areas in the Minnesota DNR’s inventory. It consists of 71.8 forested acres of steep bluffs and deep ravines near Franconia in Chisago County. Included within its boundary is a trout stream, a hunting shack, and an 11-acre state wildlife sanctuary. The sanctuary is closed to the public and visitors are asked to “Stay back from cliffs and off steep slopes” to protect sensitive plant communities. There are no maintained trails, but there is a forest road and worn footpaths that together complete a 3.2-mile circuit of the site.
Visitors to Lawrence Creek SNA this week (May 6 to 12, 2018) will see Pennsylvania sedge in flower and sharp-lobed hepatica and yellow marsh marigold peaking. Other spring wildflowers in bloom this week include bloodroot, white trout lily, large-flowered bellwort, large-flowered trillium, and Virginia spring beauty. Louisiana Waterthrush, a species of special concern, has been heard here. The site contains habitat that may host Cerulean Warbler, Acadian flycatcher, and Red-shouldered Hawk. Three Helmeted Guineafowl were seen in the parking area by a surprised visitor. They apparently belong to the farm across the road and are free to roam the adjacent fields.
Checkered white (Pontia protodice) is a medium-sized butterfly with a wingspan of 1½″ to 2½″. It is a southerly species and is uncommon in Minnesota. There are two overlapping broods here, early June to August (spring form) and July to mid-October (summer form). The wings are white with dark markings, including a checkered pattern on the outer margin. The female has more extensive markings than the male, and the spring form has darker markings than the summer form. The larva (caterpillar), known as the southern cabbageworm.
Checkered white populations have drastically decreased in eastern Unites States, and the butterfly is now scarce or extirpated in some areas where it was once common. It appears stable in the west. The cause of the decline is unknown, though habitat loss is certainly a contributor. It is possible that the extremely abundant introduced species cabbage white is displacing native whites, including checkered white. It is also possible that checkered white is a western and midwestern species that only sporadically became abundant in eastern agricultural fields. It remains to be seen whether the decline will continue to spread westward.