October 2019

A phenology year - autumn is awesome

Marla Mertz, Marion County Conservation

What we have seen this past month

We experienced a rare sighting of the Harvest Moon on Friday, September 13, before the official arrival of fall on September 23. The Farmer’s Almanac contributing astronomer, Joe Rao, says this combination is typically a once-in-a-20-year occurrence, but unfortunately, you’ll have to wait even longer than usual for your next chance to see it in the U.S. Rao says the next opportunity to catch it will be roughly 30 years from now, on August 13, 2049. So mark your calendars.

The subtle silence of songbirds has begun. Most all of our long-distance migrants have begun their south-bound journey. These songbirds are not in a huge rush in the fall and will take their time to get to where they are going. Spring migration is the mad rush and push to get to their breeding grounds before territories are taken. We always have a few stragglers from the North, that come through later than we think is normal. It is the very end of September, but we still have many hummingbirds making their way to South America.

Most all of the insect eating birds have moved on, so we will have to wait until spring to listen to their song of spring. Broad-winged hawks have been making an appearance high in the sky, along with osprey flying through. Hawks, bald eagles, and vultures are moving, so keep your eyes open! The turkey vultures are flying in large groups called, kettles, and loving these windy days for ease of movement. As the turkey vultures move on beyond the Gulf of Mexico, the eagles from the north will be moving in. Many visiting eagles will move toward the Mississippi, but many eagles overwinter around the reservoirs here in Iowa where water stays open. Pelicans are still moving with large groups arriving daily. The mudflats with green growth are dotted with the many great egrets. They stand out on a foggy day as their brilliant white feathers reflect the light. The blue-winged teal have been a little slow at moving into the area. The Canada geese are gathering in large groups with all of their young of the year.

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The prairies that were bursting in yellow, white, and purple have started to fade by the end of the month. Indiangrass and big bluestem are really making a colorful statement. Large stands of goldenrod and the many species of asters are about the last of the blooming plants and will nourish the straggler birds, bees, butterflies, and many other insects. Just as spring abounds with new life, fall seems to be neck-and-neck in the rush of creature retirement. Insects and spiders are the most abundant creatures on earth. Some will go through a period of dormancy, others will perish, die, migrate, or lay many eggs awaiting for spring. It has been a good year to see many black and yellow orb weavers and other species that we will call “guardians of the gardens.” Orb weavers are always on patrol with their circular webs throughout the grasses. Other types of orb weavers and spiders that live within the trees that are working just as hard.

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The woodland edges have been blooming with great blue lobelia, snakeroot, and a few species of asters, and goldenrod. The more rare fall orchid species of oval ladies’ tress and the very tiny coralroot are just beginning to appear. Look down low to observe these tiny beauties. The colorful fungus/mushrooms will be bursting along the woodland floors soon. Some species have already started to appear and with the rains that we have been receiving it should be a bountiful year. Some people will “hunt” for mushrooms with their knowledge and experience, others, like me, find them fascinating to look at up close and personal.

The wetlands are quieter now. Dragonfly and butterfly migration is in full swing. Snakes and turtles are returning to their winter homes. A few magnificent birds that stop by for a small rest and feast are on their way out. The dragonflies found in some of our areas are the small meadowhawks that are normally red in color with different variations of markings, including the variegated, blue-faced, autumn, and band-winged. A few spotted spreadwings and damselflies have also made their appearance for the fall. Green herons and other small shore birds can be seen in smaller, quieter bodies of water while feasting on frogs and fish.

The monarchs have mostly left Iowa, but there are always stragglers. Many people spend a lot of time in August and September tagging the super generation to help with citizen science data. The tagging helps with origins of the monarchs that reach Mexico, mortality, geographic distribution, and the timing and pace of their migration. Other species seen in September were orange sulfurs, dainty yellows, Eastern-tailed blues, common buckeye, checkerspots, viceroy, meadow fritillaries, fiery skippers, cabbage white, a few common wood nymphs, and silver spotted skippers.

The fawns’ spots are fading very fast and a few bucks have been seen in the area. Their antlers are not all nice and polished, as of yet, but still working to get all the velvet layer off. Their coat is a little scruffy as their new coat begins to grow. Look for the noticeable rubs on twigs, branches, and even the stalky compass plant in the prairie that feels a lot like sandpaper. The grey squirrels and chipmunks are caching in on the abundance of hickory nuts and acorns (mast) produced this year. Squirrels and chipmunks take advantage of certain kinds of tasty mushrooms growing in the area.

Snakes are returning to their wintering hibernation area, called a hibernaculum. Remember, reptiles and amphibians are cold-blooded, so are only as warm as the environment around them. Finding snakes on roads, rocks, and brush piles will be more common as they will need the sun to warm their bodies enough to continue feeding. As of late September, we are in full snake migration.

A closer look at something from the previous month

As the north winds bring cool air, migration and dewy mornings, the glistening of spider webs seem to appear from out of nowhere. Those large, spiraled webs are dotted throughout the landscape like works of art.


The most abundant of Iowa spiders are garden spiders, also known as orb weavers, are also some of the most fascinating. Orb weavers offer benefits to our ecosystem by controlling numerous insect pests, are not aggressive, and seem to flee immediately upon feeling threatened. With an open mind, let’s take a short venture to your nearest garden or wildlife area, camera or not, and take a peek at a few of Iowa’s orb weavers. Known for their colorful, intricately patterned abdomens, garden spiders are the common name for the genus Argiope, which means “with a bright face” in Latin. As a relative to an insect, there are some noticeable differences. What are the differences between insects and spiders? Insects usually have six (6) legs and spiders have eight (8). Insects have three (3) main body parts (head, thorax, and abdomen) while spiders have two (2) body parts (the head and thorax fused together, called cephalothorax, and abdomen). Insects have antennae, normally two (2) pairs of wings, and two (2) compound eyes with several simple eyes. Spiders have no antennae, no wings, and have eight (8) simple eyes, but no compound eyes.

Most spiders are not long-lived creatures. Depending on where you live, most orb weavers don’t live a full year. For the female, she may die at the first hard frost. She has probably mated and her young may remain in the egg sac in a dormant state until the following spring. There is a high mortality rate to the egg sacs and are quite vulnerable to wasps, flies, and other insects. The male is also more of a traveler. During his travels, he may choose to court a female by ‘plucking’ at her web. Male weavers usually die after mating.

Spiders are unique as they spin silk from spinnerets on their abdomens. The orb weavers get their names by the shapes of their webs and are the infamous design for Halloween decor. They spin webs of smaller circles within larger circles, similar to spokes on a wheel. The spokes of the wheel usually go from the center outwards to their anchoring points, like a flower, stem, or leaf. Once the main structure of the web is complete, a sticky layer of silk is laid down in circles between the structured points. The spider uses one set of legs on the interior circle and one set on the next structural layer where the “sticky line” is created in the middle.

An activity to try!

Do you like geometry? That might be a scary question for some of us, but there are some really fun activities that can apply principles of geometry, architectural design, and engineering all by learning and observing our backyard wildlife. Check out these links and learn from the orb weavers! Make your own observations and activities involving wind direction, temperature, angles, heights, direction of a spider’s abdomen, and surface area covered. Please note that spiders and their webs should only be observed, not damaged and or harmed.

Learn more about spiders here:

    • Project WILD Activity Guide - Project WILD is an interdisciplinary, supplementary environment and conservation education program for educators of kindergarten through high school young people.
      • Spider Web Geometry: Math, Science, Language Arts, Art
      • Interview A Spider: Discussion, reading, research, creative writing, interview
    • Spider Webs: Creepy or Cool? - Mathematical Ingenuity
    • Garden Spiders: Weavers of Delicate Webs
    • Wild Kratts - Secrets of the Spider’s Web (SO2E08) -Storyline: Two miniaturized Kratts explore the world of the spider and how it creates its web, finding clues along the way that indicate what spider silk is made of that will help Aviva to replicate it.
    • Keepers of the Animals, Native American Stories and Wildlife Activities for Children by Michael J. Caduto and Joseph Bruchac, Sticky Web activity, page 37 and other fun activities about webs and spiders
    • Iowa Public Radio Talk of Iowa with Charity Nebbe and Iowa State University Extension Entomologist Donald Lewis.

What we are expecting to see next month?

Phenology happenings in Marion County, Iowa

As we notice the things in nature that are changing, we'll be adding to this calendar.

Each week a new photo of the woodland creek and the wolf tree will be added to each album! Both of these locations are within Cordova Park. This park is managed by Marion County Conservation.