When the calendar flips over from August to September I get a feeling akin to the moments before being reunited with a life long friend. The summer is ending and September brings us just a bit closer to my dear friend Autumn. So many lovely attributes make this month special. This edition of the Nine Minute Naturalist will dive into the secrets of September.

The most unique attribute of September is the mass migrations. While animals and insects migrate in many other months, September seems to host the greatest volume passing this portion of the Blue Ridge Mountains. The raptors are the most visible and voluminous of our migrators. Every year Hawkwatch.org tallies the raptors passing by vantages all over the North America. The Rockfish Gap site routinely tallies over 25,000 raptors each September with the bulk coming from September 15-25^th. One of my favorite sites to behold each September is the swirling and spiraling “kettles” of broad-winged hawks rising on thermals of air. Broad-winged hawks make up the greatest bulk of the raptor migration and set September apart as the month to focus on migrations. Be sure to venture to an overlook near you to watch for migrating raptors in mid-September. Here is the link to follow the daily submissions of raptors seen at Rockfish Gap: https://www.hawkcount.org/index.php

Kettle

While raptors moving south are the obvious phenomena, insects also add to the migration spectacle. The most famous insect migrator is undoubtedly, the monarch butterfly.  Almost miraculously, these insects begin their fall journey from Canada down to Central Mexico dazzling us with their perseverance and beauty. Hawkwatch spotters at the Rockfish Gap hawkwatch site also keep track of each monarch seen as they pass south so you can keep abreast of the increasing monarch numbers as the month progresses.

Monarchs are not the only insect moving in mass. Dragonflies are sure to fill the sky each September. Many times, as I wait at an overlook for raptors to begin heading south, I am treated by the vast numbers of dragonflies flying just over the treetops. They have been known to migrate in such large numbers that they are picked up on radar. Learn a bit more about dragonfly migration here: https://www.tnfw.org/nine-minute-naturalist-the-mini-migrants/.

Dragonfly

Another fixture of September is our native insect population making themselves seen. The native fall webworm emerges in late summer to form silk webs at the end of branches. This indiscriminate caterpillar will host in over 100 tree species from Canada to Mexico. They form these webs as a cover to allow them to feed and mature without fear of predation. They will develop in these webs until early fall. While unsightly, this feeding method does little harm to our forest since most trees have entered a dormant period and are preparing to shed their leaves soon.

Webworm silk web

Another native insect that demands attention in September is the locust leafminer. This beetle is active in late summer chewing tunnels through the leaf layers of black locust trees. This feeding results in locust trees turning prematurely brown. Like the fall webworm, the appearance may cause alarm but little damage can be done to leaves as the trees prepare for leaf drop.

Even with these interesting features of September, the aspect I celebrate the most is the coming of the fall equinox. The word equinox means equal night. On September 23^rd, the sun is aligned with the equator bringing us a 24-hour period of equal day and equal night. That is the day I get to celebrate the arrival of my long-lost friend Autumn.