October 2021 – Discover-Nature

Giraffes

The giraffe, Giraffa camelopardalis, is the tallest animal in the world. Currently, it is classified as one species with nine subspecies, although taxonomists do not all agree on this. A group is properly called a “tower” of giraffes unless they are observed in motion, in which case we refer to them as a “journey” of giraffes. Giraffes have several interesting characteristics that we will explore.

Giraffe tower, Giraffa camelopardalis, by Richard Droker, 2014

Giraffes have a black prehensile tongue about 18″ long. The upper lip, also prehensile, in combination with the tongue, is used for grasping, holding, and pulling whole branches through their mouths to strip off all of the leaves and thorns. Their preferred food includes leaves, fruits, and flowers of woody species. The thorny acacia tree is a special favorite. Giraffes are ruminants, using strong stomach muscles to bring food back up to their mouths for chewing multiple times. For complete digestion, food makes its way through a giraffe’s four stomachs.

Giraffe, Giraffa camelopardalis, by Chester Zoo, 2009

Adult giraffes may reach heights of 14′ to 19′ and weigh from 1800 pounds to 2600 pounds. Their necks, up to eight feet long, have the same number of vertebrae as other mammals. As calves grow, cervical vertebrae grow longer. The neck is very long, yet too short to reach the ground, so a giraffe must spread and bend its front legs in order to drink. Giraffes do not need to drink more than once every few days, though, getting most of their water from their food.

Giraffe, Giraffa camelopardalis, by John Hilliard, 2010

A giraffe’s circulatory system includes several adaptations to accommodate its height. The heart is one of the largest muscles in the body at two feet long and weighing 25 pounds. It must generate almost twice the blood pressure of a human. With a resting heartbeat of 150 beats per minute, it pumps sixteen gallons of blood each minute. To prevent fainting, a network of veins and muscles along with several one-way valves, regulate blood flow, keeping it from rushing to or away from the head when it is lowered or raised. Giraffes have smaller red blood cells and many capillaries making oxygen absorption quicker to supply the energy needs of the muscles.

Giraffe, Giraffa camelopardalis, by Sergey Yeliseev, 2010

Giraffes sleep less than an hour each day, taking several short naps while standing. They give birth while standing and calves can stand and walk within an hour of being born. Their hooves, up to twelve inches in diameter, are made for comfortable walking and running. Adults can sprint short distances at 40 miles per hour or sustain a loping speed for several miles at 20-30 miles per hour. Their speed and size keeps adults safe from most predators, although calves are susceptible to lions, hyenas, leopards and wild dogs. Their normal life span is 25 years in the wild, but almost 50% of all calves are lost to predation before reaching adulthood.

Giraffe, Giraffa camelopardalis, by Bernard Spragg, 2012

Giraffes are listed as vulnerable on the IUCN Red List, with 90,000 individuals living in central and southern Africa, down from a population of 150,000 thirty years ago. The main threats are habitat loss and killing for the bushmeat market. As human populations expand, the need for firewood and livestock grazing areas results in shrinking forests and savannas. Another factor negatively impacting populations is climate change, including a severe drought across much of the central plains in 2017. Private game reserves and national parks offer protection, but they are limited in size and are being used by many species. Giraffes are vital to keeping ecosystems in balance, eating browse unreachable by other species, opening new areas, and promoting growth of grasses and brush for food for many smaller species.

Illinois’ Hawks

Migration is in full swing for hawk species in North America. Many hawk species leave North America to spend the winter in Central America or South America. October thermals, updrafts created by the sun warming the earth, provide a boost for hawks. In northern Illinois, we can observe about sixteen species of raptors including eight hawks.

Red-tailed hawk, Buteo jamaicensis, by Sandy&Chuck Harris, 2016

Cooper’s hawk, Accipiter cooperii, by TexasEagle, 2015

Depending on the species and their breeding locations, hawks migrate from late summer in Arctic regions through autumn and early winter in the midwestern United States. Hawks leaving breeding grounds in Arctic regions in late August arrive in Illinois six to eight weeks later after a journey of 2,000 miles or more. Some will spend the winter here, and others will join resident hawks of Illinois and continue heading south for the winter.

Sharp-shinned hawk, Accipiter striatus, by Jerry McFarland, 2016

Red-shouldered hawk, Buteo lineatus. By Loren Chipman, 2014

There are eight species of hawks found in Illinois throughout the year. The most common is the red-tailed hawk, Buteo jamaicensis, which is seen year-round soaring over fields or open areas hunting for prey. Another common species is the sharp-shinned hawk, Accipiter striatus, the smallest hawk in North America. They breed in northern Canada and winter in Central America and are notorious for raiding backyard bird feeders. Cooper’s hawk, Accipiter cooperii, feeds exclusively on other birds in forests and woodlands. It is hard to tell apart from the sharp-shinned hawk, but is generally larger. Another year-round resident of forested areas is the red-shouldered hawk, Buteo lineatus. Populations have been increasing over the last fifty years, despite the clearing of forested lands, a constant threat to the species.

Rough-legged hawks, Buteo lagopus, by Robert Pruner, 2016

Swainson’s Hawk, Buteo swainsoni, by Tom Benson, 2015

Broad-winged hawk, Buteo platypterus, by Stan Lupo, 2015

The remaining four species are less well known due to remote habitat or because they are only here during migration. The broad-winged hawk, Buteo platypterus, breeds in deciduous forests near wetlands. There is a small population breeding in Illinois, but it is usually observed during migration. Swainson’s Hawk, Buteo swainsoni, also has a small breeding population in far northwest Illinois. This bird has the longest migration route, flying from breeding grounds in the northern United States to winter at the far southern tip of South America. Rough-legged hawks, Buteo lagopus, are the only hawks in North America with feathers extending over their legs all the way to their toes. They breed in the northern Arctic and winter in our area. Northern goshawk, Accipiter gentilis, is rare in Illinois, requiring large forests with very high nest sites. It is a fierce protector of its young, attacking any animal, including humans, who comes near the nest.

Northern goshawk, Accipiter gentilis, by Zweer de Bruin, 2017

Northern goshawk, Accipiter gentilis, by Sergey Yeliseev, 2019

Three well-known observation sites in our area provide an exciting opportunity to get out to see many of these birds, as well as other migrating species including ospreys, eagles, falcons, butterflies, cranes and dragonflies. Volunteers record their observations daily, at each of these sites, throughout the migration season which continues into early November. Illinois Beach State Park, near Lake Michigan and the Illinois-Wisconsin state line, averages over 5,000 raptors observed every year. Fort Sheridan, a little farther south along the Lake Michigan shoreline, is where we are learning about how larger bodies of water affect migration patterns. And in DuPage County, the Greene Valley Forest Preserve scenic overlook is located on the highest point open to the public. From here, observers can see several miles on clear days over urban areas, fields and the DuPage River valley.

For more information on each of these sites, take a look at:

Greene Valley: https://www.dupageforest.org/catching-nature/greene-valley-hawkwatch

Fort Sheridan Hawkwatch on Facebook

Illinois Beach State Park: https://www2.illinois.gov/dnr/parks/pages/adelinejaygeo-karisillinoisbeach.aspx

Asters

Asters, a Greek word for star, bloom between early August and the first frost. The late blooming period is thought to be an adaptation to attract pollinators without competing against the majority of flower species in our area that bloom in spring and summer. In return, asters provide an important source of nectar and pollen during the latter part of the year.

Short’s aster, Symphyotrichum shortii, by Dan Mullen2009

Asters are classified by flower arrangement and leaf shape. They are all members of the composite family Asteraceae, but many of the species that live in our area have been reclassified into a new genus Symphyotrichum, due to DNA differences with those species found in the old world. Native species have both ray and disc flowers. The tightly packed disc flowers make up the center of what is viewed as the whole flower or in florescense, and the petals coming out from the center are the fertile ray florets. Seeds are wind-born and have pappus, a piece of fluff, attached to them, allowing the wind to efficiently move them over long distances.

Panicled aster, Symphyotrichum lanceolatum, by Robert H Mohlenbrock, 1989 @ USDA NRCS Wetland Science Institute

Heath aster, Symphyotrichum ericoides, by Jennifer Anderson, 2001

The calorie-rich nectar is eaten by insects bulking up for hibernation including queen bumblebees, hoverflies, and several ant species. Migrating butterflies, including monarchs, depend on the nectar for quick energy for their long travels. Pearl crescent and painted lady caterpillars feed almost exclusively on aster leaves to fatten up before pupating. Many backyard bird species over-wintering in this area eat the seeds including American goldfinch, tree sparrow, black-capped chickadee, pine siskin, and song sparrow.

Expressway aster, Symphyotrichum subulatum, by Robert H Mohlenbrock, 1995 @ USDA NRCS Wetland Science Institute

Calico aster, Symphyotrichum lateriflorum, by Robert H Mohlenbrock, 1989 @ USDA NRCS Wetland Science Institute

Hairy aster, Symphyotrichum pilosum, by Jennifer Anderson, 2001

Pictured with this article are many of the large variety of asters in bloom around the area. Consider taking a walk in area woodlands to see Drummond’s aster, calico aster, heart-leaved aster, and Short’s aster. A walk across the prairie may yield sights of rush aster, bushy aster, blue aster, heath aster, New England aster, and hairy aster. You can also observe in fens and marshes panicled aster, shining aster, and bristly aster. And even as you are driving home, be watchful for the expressway aster, which can easily tolerate the salt spray along the embankments of many byways.

Chinook Salmon

At this time of year, many species are migrating south to spend the winter months in warmer climates. But, a few species are moving north including the Chinook salmon, Oncorhynchus tshawytscha. The largest species of Pacific Ocean salmon, they are blue-green on the head and back and silver on the sides. Their tails, backs, and upper fins have black spots, and the tooth gum line is black. Salmon average three feet in length and weigh thirty pounds, but can grow past five feet and 110 pounds.

Chinook salmon, sometimes known as king salmon, are native to the northern Pacific Ocean and freshwater streams and rivers in the Pacific northwest. They are born from eggs laid in autumn’s cool waters that hatch in springtime when those waters start to warm. Young salmon feed on insects and small crustaceans in freshwater habitats until they become adults between one and two years of age. An anadromous species, meaning they live in both freshwater and saltwater habitats, as adults, they travel downriver to the ocean, where they will spend the next one to five years following the warmer ocean currents, eating a diet of nutritionally-rich prey including herring, sandlance, and squid, allowing salmon to reach their large size.

Oncorhynchus tshawytscha, Chinook salmon by Dan Cox, USFWS 2013

Salmon are also known as semelparous, meaning they spawn once and then die. As salmon reach maturity, they return in autumn to the rivers where they were born. Females dig a nesting hole, called a redd, in which she deposits 3,000 to 14,000 eggs. Males fight to be the one that pairs up with each female and fertilizes her egg nest. A benefit to being big is that larger females lay more eggs and dig deeper redds. A deep nest protects eggs better by not exposing them to faster, surface water. Both parents guard the eggs for the first few weeks, but the parents will die before winter, months before the eggs hatch.

Oncorhynchus tshawytscha, Chinook salmon by Mike, iNaturalist

Returning salmon and their eggs offer a buffet for more than 125 species that depend on them as a food source just before winter. Marine mammals including whales, orcas, sea lions, and harbor seals hunt large schools of salmon as they converge on the Pacific northwest coastal areas. As salmon enter the river systems, they attract eagles, seagulls, herons, kingfishers, murres, and puffins. A great variety of land mammals also make their way to the waterways including bears, wolves, minks, martens, weasels, and fox. Shorebirds wade into deep water to snack on any eggs that may escape a redd. Migrating birds on the Pacific flyway feast on salmon that are dying after spawning. Insects feed on the decaying bodies, and in turn, are food for the smaller birds migrating south.

Chinook Salmon (Oncorhynchus tshawytscha) spawning in Los Gatos Creek by Robin Agarwal, 2020

Chinook salmon populations have declined in recent decades and some populations of Chinook salmon are federally listed as endangered. Loss of snowpack and shrinking glaciers have reduced the amount of water in streams and rivers. Along with shallower waterways, warmer summers are raising stream temperatures leading to habitat where parasites and disease grow and attack more easily. Severe storms and forest fires contribute to less undergrowth and more soil eroded into rivers causing siltation that constricts the passage of water and river inhabitants. Supporting improvements in land use practices and saving habitat will greatly benefit Chinook salmon as well as the many other species they live with.

Seeds

Autumn is the time for many plant species to spread their seeds before dying or entering dormancy for the winter. Every seed is a potential new plant, but it is unable to move on its own. Seeds must rely on wind or water or animals or gravity. There are several ways that seeds leave the parent plant and move to new locations. These methods are described below including examples of plants that you can observe on your local walks in the coming weeks.

Jack-in-the-pulpit, Arisaema triphyllum by Don Arnold 2021

Seeds are contained inside the fruit of plants. The size, shape, texture and presence of special structures on both the fruit and the seed contribute to the method of travel. Some fruits travel on their own, carrying the seeds with, but many ripen while still on their host plants, then split open and allow the seeds to travel by themselves. Seed and fruit surfaces may contain spines, glues, fluffs or hooks that aid the seed in its travels.

Common dandelion seed, Taraxacum officinale by Patrick J Alexander

Black maple seeds, Acer nigrum by Steve Hurst, ARS Systematic Botany & Mycology Laboratory, PA

Wind can move seeds a short distance or many miles depending on the air speed and direction. Winged fruits containing one or more seeds are pulled down by gravity while being carried short distances by the wind. A childhood favorite, the “helicopters” from maple trees, recently fell. Others using the wind are lightweight fruits and seeds with a cotton-like, feathery plume attached that can travel great distances on windy days. Examples include fruits of the quaking aspen and seeds from milkweed, thistle, and dandelion. Small, extremely light seeds may be carried on their own by even a light breeze. Eastern prairie-fringed orchid and poppy seeds are dust-like in form, and are easily whisked away from flower heads by any air movement.

Bur oak acorn, Quercus macrocarpa, by Steve Hurst, ARS Systematic Botany and Mycology Laboratory, Georgia

Animals, including humans, move many seeds, sometimes unknowingly and other times with a purpose. Some species of plants have an aril, a small food treat, attached to each seed. Insects will carry seeds back to their nests to eat the aril, but discard the seed. Ants move hundreds of yellow dog tooth violet and Jack-in-the-pulpit seeds every autumn. Many seeds are contained in fleshy fruit eaten by animals that later excrete the undigested seeds elsewhere. Fruits harvested by humans are moved indoors or to local farmers markets and grocery stores. How many of you have apples, strawberries and apricots at home? Nuts and acorns have a leathery covering containing one or more seeds and are often cached by birds and squirrels for the winter, then forgotten and left to germinate in spring. Many fruits are covered with barbs and hooks that attach to animal fur or human clothing as the plant is brushed against.

Ticktrefoil, Desmodium seed with barbs by Janet Tarbox, 2012

Sycamore seed, Platanus occidentalis by Amehare, 2006

Many plants that grow near water, including oceans, lakes, and rivers, grow corky fruits containing air spaces that allow the fruits to float and travel with the water currents. Sycamore and water lily are two examples. Coconut palm originated in the South Sea Islands, but can be found growing on most tropical shorelines around the world. One last travel method is used by explosive fruits that burst and shoot out their seeds for several feet in all directions. Look for spotted touch-me-not, lupine and plants in the bean and pea families.

Heirloom poppy seed, Papaver paeoniflorum by Don Arnold, 2021.

Big seeds often travel short distances and small seeds may travel far away. Round seeds move across the uneven terrain and flat-sided seeds stay wherever they initially land. If every seed fell beneath its parent plant, competition for resources would become fierce, and many plants would die. It is important that seeds can move about, finding suitable locations to grow over a wide area contributing to the natural diversity of habitats.