Month: February 2021

Bee Fascinated

There is a lot of snow on the ground around Chicago, and temperatures are in the deep freeze.  But there are hundreds of bees in nests spread over our landscape that are all comfortably feeding on the honey they have stored away for the winter.  How do bees create this great store of food? 

Bee foraging Buttonbush, by DonArnold

Bees forage for nectar and pollen among the many flowers in our backyards.  Nectar, a sugary fluid secreted by plants to attract bees and other pollinators, is sipped by worker bees for quick energy.  It is also collected and brought back to the nest to be mixed with enzymes secreted by the bees to form honey.  Pollen, a fine, powdery substance used in flower reproduction, is composed of amino acids, vitamins and fat that are all essential for bees.  Together with honey, it can be stored for long periods in the nest to provide food for winter.

Bee with full pollen baskets by DonArnold

When visiting a flower for nectar, a bee collects pollen on the hair covering its body.  They will brush the pollen from the hair into collection baskets on their legs.  A bee will visit from 100 to 1000 flowers to get a full load of pollen before returning to the nest to deposit it.  A single load takes 30-60 minutes to collect, and the bee will make an average of 10 trips a day.  There are thousands of bees foraging every day, and as each bee enters a flower patch, she can be most efficient if she knows which flowers have a full load of nectar and pollen available. 

Birds’ Foot Trefoil, Lotus corniculatus by Robert H Mohlenbrock
Borage, Borago officinalis by Scamperdale, 2009

Flowers are constantly refilling their nectar tubes during daylight hours.  Different flowers produce nectar at different rates from two minutes for borage, Borago officinalis, to almost 24 hours for bird’s foot trefoil, Lotus corniculatus.  The nectar is not visible, located in a long, slender tube at the base of the flower.  A bee will crawl into the flower and drink from the tube using her long tongue.  Foraging bees will not land on a flower that has recently been emptied of nectar, but how do they know which flowers to skip?

All insects are covered with an oil giving each species a particular scent.  Studies show that after carefully washing the feet of several bees in a mild solution and painting this solution on flowers full of nectar, foraging bees avoid these flowers.  The bees can smell the scent left by a previous visitor, can tell how old the scent is, and know how long that particular flower species takes to refill the nectar.  Footprint odor has also been identified as an aid to the bees when they return to their nest.  Landing close by the opening, bees walk the last short span, using scent to guide them to the exact spot of the nest opening.

IL Farm road with mowed edges, by R Boed

Bees require large numbers of flowers for nectar and pollen to feed their colony.  They have thrived quite well up until the last hundred years when there has been a shift toward fewer flowers in both farmland and urban areas.  In the agricultural areas, before mechanized plowing, many fields were bordered by flowering plant species.  Since the automated plow, borders have been removed in favor of planting as much crop as possible.  Along country roads, flowering edges are often mowed.   In urban areas, the popular movement toward more lawn has also removed many flowering plants, especially in city parks and other recreation areas.  These changes greatly reduce the amounts of pollen and nectar available to bees.  You can make a difference in your own backyards by planting flower beds or areas of ground cover using flowering species.

Winter Tree ID, pt.2

Villages, public parks, and forest preserves in our area contain thousands of trees for our enjoyment.  Being able to identify some or all of these can make our walks more fun.  In the last blog, I identified several tree characteristics that can be used in tree identification in the winter.  Here are some of the more common trees you may find in this area, along with their winter identification characteristics.

Silver Maple bark, by Jerry Jenkins, Forest Atlas Project
Silver Maple flower bud, by Jerry Jenkins, Forest Atlas Project
Silver Maple twig, by Jerry Jenkins, Forest Atlas Project

Silver maple, Acer saccharinum, is a native Illinois tree with bright yellow/green fall leaf colors.  When looking at a twig, the terminal and lateral buds will all appear slightly reddish in hue and rounded or pointed.  Remember that lateral buds are where new flowers or leaves will grow.  If the buds are clustered, this is where flowers will bloom on the twig.  The twig is slender and gray to red in color, with buds arranged opposite one another.  If you scratch the twig with a fingernail and take a sniff, there is an unpleasant odor.  The bark is smooth on young trees, becoming shaggy on older trees.

Hackberry bark, by Jerry Jenkins, Forest Atlas Project
Hackberry twig, by Jerry Jenkins, Forest Atlas Project

The hackberry, Celtis occidentalis, a favorite street tree, is a large, fast growing tree that can reach heights of 40 to 60 feet.  Native to Illinois, the hackberry may live for 150 years or more.  Twigs in winter lack a terminal bud, but have lateral buds that are brown, flat, and triangular in shape.  Lateral buds display an alternate arrangement  along very thin twigs.  As each new twig grows at a slight angle from the bud, branches take on a zig-zag appearance.  The bark, smooth and light gray, is covered with light colored lenticels, and is often times covered with wart-like bumps, their density being greatly variable.  Cutting open a twig reveals a banded pith with visible cavities.

White Oak bark, by Jerry Jenkins, Forest Atlas Project
White Oak buds, by Jerry Jenkins, Forest Atlas Project

White oak, Quercus alba, is one of our most popular native hardwood trees.  The state tree of Illinois, white oak is used for building dozens of items including cabinets, watertight barrels, floors, caskets, and pianos.  In winter, look for bark that is light gray to silver in color.  The bark can be quite variable from tight, shallow ridges to broad, loose flaky plating.  Many trees exhibiting different bark formation on different parts of the trunk.  Twigs  display small, rounded, and reddish buds.  Lateral buds are alternate  on twigs that are slender, smooth and slightly reddish in appearance.  Terminal buds are clustered with broad, hairless scales.

Black Walnut leaf scar, by Bruce Kitchoff,c-2015
Black Walnut pith, by Bruce Kitchoff,c-2015

Black walnut, Juglans nigra, is a slow growing tree with a large, shady canopy and rich, dark-brown hardwood.  The wood will not warp, can be polished to a high luster, and is highly prized for furniture and veneers.  The buds are gray with a light, fuzzy coating of hairs and arranged alternately along the twig.  The leaf scars are heart-shaped and contain a very distinct bundle scar that looks like a “monkey face”.  The pith is chambered, a distinctive trait found only in black walnut and butternut trees.  The bark on this tree is dark brown, with high ridges and deep furrows often arrayed in a diamond-shaped pattern.

Bitternut Hickory bark, by Jerry Jenkins, Forest Atlas Project
Bitternut Hickory buds, by Jerry Jenkins, Forest Atlas Project

Bitternut hickory, Carya cordiformis, also a member of the walnut family, is a medium sized tree, growing 50′-80′ tall with a narrow canopy.  This wood burns with an intense heat and is often used for smoking ham, bacon, and other meats due to the distinctive flavor imparted by the smoke.  Twigs are thin, shiny, and greenish- to grayish-brown.  The alternately arranged buds are bright yellow to sulfur-yellow, covered by two to four large scales that join one another along the edges without overlapping.  The bark is light gray, appearing in a diamond-pattern with very shallow ridges.

These trees are some of the most commonly planted in urban communities and found in area forest preserves.  All are native to Illinois, are hardy in urban settings, and provide food and shelter for many native wildlife species.  Winter identification characteristics are easily visible and a great place to learn how to use a key.  Take a walk and get started soon!

Winter Tree ID, pt.1

Many people can identify an oak tree or maple tree during the summer, but how can you ID a tree without leaves?  There are several basic characteristics used in tree identification.  Many of these are readily visible in winter.  When looking at a tree, inspect several of the twigs, the smallest branches on a tree, to rule out any anomalies that may be present on only one.  Different characteristics may appear on more than one tree, but when taken all together, a unique combination of traits will identify a single species.  As you read the following, a drawing of a twig and all its relevant parts can be referenced at https://mekwamooks.wordpress.com/winter-id/.

The terminal bud, located at the tip of the twig, is where new growth will start from in the spring.  Note its size relative to the twig, the bud’s shape, and whether or not it is covered with scales.  Buds may be naked, not having any scales, or covered with overlapping scales, or scales may meet at their edges.  Lateral buds are arranged along the length of the twig, and they are the site from which a new leaf or flower will grow next year.  They will appear on the sides of the twig as you move along it.  The arrangement may be opposite, when two buds are at the same point on either side of the twig, or alternate, when a bud on one side is spaced a few inches along the twig from the next bud on the other side.

Lenticels are specialized cells where gas exchange takes place during the growing season.  They appear as light or dark spots along the twig.  Note the color, size and amount found on a twig, or whether there are none.  Running your fingers over the surface of the twig allows you to tell if the lenticels are smooth or rough and raised.

When leaves fall off the tree, they leave behind a leaf scar.  Take note of the size and shape of a scar.  Is it round, oval, heart-shaped or some other shape?  Inside the leaf scar is the bundle scar, where the phloem and xylem layers that transport water and food entered each leaf.  The arrangement of the bundle scar in addition to the size and shape of both scars is very helpful in determining the tree species.

The pith inside the twig is another part to use in identification.  You will need to break off a twig and slice it lengthwise with a sharp pocketknife to see the center structure of the twig.  It can be solid, hollow, spongy or chambered.  This structure is found in young branches and is used to store and transport nutrients throughout the plant.  As branches mature, storage and transportation will move to the xylem and phloem layers found just underneath the bark. 

Peeling bark-Shagbark Hickory, by Jerry Jenkins, Forest Atlas Project
Smooth bark-Musclewood, by Jerry Jenkins, Forest Atlas Project
Warty bark-Hackberry, by Robert H. Mohlenbrock, hosted by the USDA-NRCS PLANTS Database

Bark, another highly visible feature, comes in a variety of colors from gray to tan to dark brown to black.  Many species may have a hint of red tones.  Identifying the texture of bark is very important.  Is it smooth to your touch?  Is it covered with warty patches?  Some trees have bark that peels off, and it is important to note how the peel starts.  Is it the top and bottom ends of each strip that are loose, or the middle that is pulling off to the right or left?  Is the bark paper thin and coming off in loosely curled sheets?  Thicker bark has a much rougher appearance.  Does the bark run in ridges and furrows?  Does it appear to be a diamond-shaped pattern on the tree?  Some bark looks blocky, with no discernable pattern.  Are the blocks flat to the tree or are there deep furrows between the blocks?

Blocky bark-White Oak, by Daniel O. Todd, hosted by the USDA-NRCS PLANTS Database
Furrowed bark-Bur Oak, by W.D. Brush, hosted by the USDA-NRCS PLANTS Database

As you accumulate clues, you can match them against identification guides.  A special type of guide, known as a key, will help you identify many of the species found in a given geographic area covered by  the key.  Keys present a series of questions, each with a limited number of choices to select from.  An example is “Winter Tree Finder” by May Theilgaard Watts and Tom Watts, “for identifying deciduous trees in winter.”  This book uses a series of questions about twigs to lead the user to a correct identification.

There are many keys and field guides available, but remember to choose ones that pertain to the time of year you are in.  Keys for flowers and leaves will not be of great value in winter, and many of the characteristics discussed above, such as scars and buds, will not be available to view in summer.  I urge you to get out and try this fun activity before spring.

Publications to get you started:

Winter Tree FinderMay Theilgaard Watts & Tom WattsNature Study Guild, 1970
Trees of IllinoisLinda KershawLone Pine Publishing, 2007
Keys to the Trees of The Chicago RegionRoss C. ClarkThe Morton Arboretum, 1988
BarkMichael WojtechUniversity Press of New England, 2011
The Tree Identification BookGeorge W.D. SymondsHarper Collins, 1958
Twig Parts ExplainedVolunteers @ Me-kwa-mooks Park, Seattlehttps://mekwamooks.wordpress.com/winter-id/

Backyard Birds

This year’s Cornell Ornithology Lab’s Feederwatch Project began twelve weeks ago, and we have been counting the birds in the backyard every Sunday & Monday.  We have seen nineteen different species using our seven feeders, one heated birdbath, trees and bushes, and a pond surrounded by native forbs and grasses.  Much of the pond freezes on particularly cold nights, but the mallard population keeps a portion open all the time.  Birds visit the feeders several times each day.  Every species exhibits unique feeding behaviors, using one or more of the feeders which include a covered tray, an open tray, a tube for black oil sunflower seeds, an open mesh tube for nyjer seeds, an upside down cage for suet, and seed placed out on open ground.  This attracts a large mix of birds for us to watch. 

Chickadees and red-bellied woodpeckers may eat or cache their food.  A bird flies to a feeder, takes a food item and immediately flies to a nearby covered perch, usually in one of our pine trees.  The bird may store the item in a cavity in the bark of the tree or eat the item immediately.  Hairy and downy woodpeckers eat at suet feeders, but are very vigilant.  After landing on the feeder, they will spend several minutes checking all directions for possible threats before beginning to eat.  Sparrows and cardinals select different types of seeds.  Northern cardinals have a large, heavy beak making it easy for them to break open seeds like striped sunflower that have a thick outer shell.  Sparrows have small beaks and eat correspondingly smaller seeds, including millet, safflower and black oil sunflower seeds, which have a thin outer shell.

Goldfinchs’ favorite seed is nyjer, a small, oil-rich seed from an invasive plant native to Ethiopia.  Imported from overseas, the seeds are put through a heat-sterilization process prior to distribution in the United States to ensure that invasive plants do not grow from the seed.   House sparrows take small seeds from the woodpecker blend in the covered tray house feeder.  Mourning doves and juncos feed on open ground and are found cleaning up various seeds that fall around all of our feeders.  Sparrows and mourning doves also enjoy white millet, a small, starchy grain that provides a nutritious meal, served in an open tray. 

Occasionally, a red-tail hawk, sharp-shinned hawk, or Cooper’s hawk buzzes the yard.  These birds are top predators in the area and feed on the smaller birds flying to and from feeders.  Hawks will grab a smaller bird either in flight or from a feeder, grasping their bodies with strong talons, that are also used to kill their prey by repeated puncturing.  The hawks will fly to a nearby perch, high up in one of the larger trees, to eat.  Their attacks are swift and usually come from a direction that is not easily monitored by birds on the feeders.  Whether the hawk is successful or not, there are no birds to observe for a long time after one flies through the yard.

Projects, such as Feederwatch, have gathered data on various bird behaviors for many years.  Combined observations from all of North America help to identify long-term trends in species distribution, which food items attract each species, and environmental factors that affect the birds.  Observations and anecdotal evidence provide insight into species that travel and feed together, how habitat is used for food and cover, and group communication. 

The Feederwatch Project website, at https://feederwatch.org/, contains information on a variety of topics including summaries and graphs of the data being currently collected, as well as all past data.  Click on the EXPLORE button to access bird count summaries, trend graphs, and more scientific information.  eBird, another observation project hosted by Cornell Ornithology Labs, also contains an EXPLORE page with species and hotspot maps, bar charts showing population distribution over time, photos and sound recordings.  Try accessing the page for eBird / Explore / Explore Hotspots, at https://ebird.org/hotspots;  change the date in the middle top bar to “Jan, current year” and scroll in until only the Chicago area is displayed.  Hover your mouse over any one hotspot to see the number of species reported in January at that location.  Then consider signing up to create your own observational hotspot!

If you are interested in making your own bird observations, consider signing up for the Great Backyard Bird Count happening next weekend, February 12th to February 15th.  Click on the link below for more information and to sign up as a participant.

Fun sites to explore: