Contents tagged with Biology
Created: 3/26/2014 Updated: 8/9/2016
Bluebirds have been the traditional avian harbinger of spring throughout our nation’s history. However, with the various pressures applied by habitat conversion, heavy pesticide application, and the introduction of exotic competitors like house sparrows and starlings, the bluebird is a species few city dwellers will ever see in their neighborhoods again. On the other hand, human activity has been generally good for the red-winged blackbird and throughout the region---city, suburb and rural areas alike—wherever there is tall grass and some standing water, male red-winged blackbirds are arriving in droves.
As with many bird species, the males arrive first to stake out the best territories; he with the best territory will have the most mating opportunities later in the spring when the females arrive. The male proclaims his fiefdom with a loud metallic call that sounds a bit like a squeaky swing set. At the same time he leans forward to display his eponymous red wings, really just a patch of bright red feathers on his wrist that contrast well with the rest of his jet black body. While it’s a small patch of color, it makes all the difference. The bigger and more intense patches attract the most mates.
In fact, scientists have influenced mating opportunities by experimentally cutting the red feathers off of some males and gluing them on to others. Much like humans who are stereotypically impressed by a man driving a red sports car, regardless of his age or personality, female red-winged blackbirds apparently look no deeper than the red patches on a boys wrists.
Red Sports Car
Hand-me-down van from your parents
Once the male has established his territory, he will aggressively defend it against all interlopers, including you. It can be fun, and a little daunting, to walk past a breeding colony of red-winged blackbirds. Most will simply scream at you but usually one will sneak up behind you and, when you are not looking, he may drop out of the sky and hit you on the back of the head. Keep your eyes to the sky this spring.
Created: 12/11/2013 Updated: 8/9/2016
After reading yesterday's Gizmodo article titled "The Fascinating Story of why U.S. Parks are Full of Squirrels" by Adam Clark Estes, we had our Curator of Urban Ecology and resident squirrel expert (he runs projectsquirrel.org, a citizen science project) Steve Sullivan, write a response. The result is a historic and eye-opening look into the population of squirrels (and other game animals) from a biologists point of vew.
This is a fun article as far as it goes. It neglects two important points though, one having to do with extirpation and the other with invasion.
Eastern grey squirrel
Sure, we encouraged squirrels to live in parks. Wildlife of all kinds has potential to bring joy as we watch and interact with it. In fact, there is a claim (I’m still looking for the primary source) that Oak Park reintroduced fox squirrels by trapping some in Oklahoma. So why did we have to add squirrels to our parks and why did Oak Park have to import them from so far away? Over hunting and habitat destruction.
As settlers spread they relied on wild game to supply much of their food. Since we need to eat all year, people were hunting and trapping all year. Bison, deer, and turkey are the ones we often think of in this context but in fact beaver, bear, bobolink, lark, curlew, duck, prairie chicken, and even squirrel were also on the menu. In fact, small animals like squirrel and many birds were likely on the menu more often than the larger species. Remember, prior to the present era, people ate far less meat than we do today and two or three bobolink were more than enough meat for a meal; a squirrel could feed four people. Nevertheless, relentless hunting reduced populations of these species significantly. Many that were once common disappeared from many states, some became extinct. Only a few decades ago, it was uncommon to see a deer and unheard of to see a turkey. Bison are found almost exclusively in preserves and elk are rare outside of them. Bobolink, duck and lark populations are tiny compared to pre-settlement times. Eskimo curlew are extinct (we ate them all) as are passenger pigeons, a species that was once one in four birds on our continent. During this time, squirrels diminished greatly, too.
Bull Elk, photo by Flickr user Amada44
Thankfully, uncontrolled hunting (in the US) has been largely solved. Hunting seasons, animal censuses, and hunter success reports ensure that our favorite game animals are almost all doing very well. So well, in fact, that many species have become pests in places where hunting is limited.
While we may have a good handle on over hunting, habitat loss is another issue altogether. One game species that is not doing so well is the bobwhite quail. This once seemingly ubiquitous species is seldom seen in many places where it once was about the only thing worth hunting. It is declining for a number of factors, most notably habitat loss. As farms are consolidated, fencerows are eliminated. These fencerows once provided shelter from the wind and rain for a wide variety of species. Without them, the landscape becomes little more than a biological desert of corn and soy fields. Almost nothing lives in these places, especially not game animals.
Bobwhite, photo by Steve Maslowski/USFWS
Thankfully for squirrels, the parks we create are often hospitable environments. When we make parks, we typically eliminate most of the natural biodiversity. Notably, we eradicate predators to the best of our ability, and we plant as many trees as we can. Both of these cases greatly benefit squirrels. As the article correctly points out, it is sometimes necessary to install nestboxes because we also remove large hollow trees just as they become naturally good homes for squirrels. Not all species respond well to such simple manipulations though. Think how hard it is to get a bat box populated.
And so, these days, after killing off most of the squirrels near us and destroying their habitats, we have created parks where they can live and, in many cases (but certainly not all), we have intentionally reintroduced them as a mobile part of the natural beauty we maintain in our cities.
Invasion is another story. The grey and fox squirrels that many of us are so familiar with are native to the eastern half of our continent. There are other tree squirrel species that evolved in the more diverse western ecosystems. However, as we settled the west, we brought our squirrels with us. The native species were sometimes shy, occurred in low numbers, or were too greasy; they were hard to hunt and not much good for food. So, we introduced the greys and foxes into these new ecosystems and, much as they took to the artificial habitats of parks, they also prospered in western habitats.
Eastern grey squirrel
Today, Eastern grey squirrels (Sciururs carolinensis) are invading the habitat of Western greys (S. griseus) and eliminating them. Project Squirrel participants may also be documenting a new invasion of fox squirrels in Colorado where they compete with Abert’s squirrel. Fox squirrels are also well-established in the Los Angeles region and are a major pest in some nut farms. Both grey and fox squirrels can also cause major damage to natural forests as they eat and scatter nuts and remove bark from trees. Over time, we expect them to change the look and feel (and thus the resident animal populations too) of some western forests. These same problems are being experienced in England and Italy where our grey squirrel has been introduced.
So, while it is enjoyable to watch squirrels in eastern parks, those that you see in western parks are often an indication of significant ecological problems brought about by people moving squirrels around.View Comments
Created: 7/22/2013 Updated: 8/9/2016
It’s Time to Get Your Bug On!
Summer has finally arrived in Chicago with it the endless array of festivals. Not to be outdone, the Nature Museum will once again be celebrating all things invertebrate with its fifth annual Bugapalooza event. So if boiling your brains out with music in Grant Park with several thousand others is not your idea of a fun time (or even if it is, you can do both) why not head over to the museum on August 2nd and delve into the delights of entomology?
We will have a great selection of bugs on display in our highly popular Bug Zoo with experts on hand to give you all the fascinating facts about these often overlooked creatures. You'll get the chance to learn about bug diets when we do our Bug Feeding Program and we'll also be doing Bug Walks on the museum grounds to show you the vast array of species that call our prairie landscape home.
Along with Bug Crafts, Bug Coloring and Bug Tattoos we will also be throwing down the gauntlet to see how adventurous you are feeling by offering you some tasty dishes to try where the key ingredient is, you guessed it, BUGS!!
Our collections staff will be on hand demonstrating the delicate art of insect pinning and we will have our neighborhood apiarist here to explain the skills of bee keeping whilst our younger visitors can learn how bees dance. You will even get the chance to see our Leaf-cutter Ant Colony up close too.
Of course no celebration of the invertebrate world would be complete without a special ‘after hours’ opportunity to visit our iconic Butterfly Haven and to cap off the evening we will be doing a First Flight Butterfly Release. To register for this great event, simply click on this link.
Created: 7/12/2013 Updated: 8/9/2016
Food: The Nature of Eating focuses on how human eating habits impact us and the planet. While this exhibit focuses on the human relationship with food, the Public Programs department teaches visitors about the importance of a balanced diet for animals through our daily animal feedings.
Two of our most popular feedings are the water snake and rats. The water snake feeding takes place every Thursday at 1 p.m. During this time our water snake feasts on a large bucket of live fish! Our attendees are glued to the glass as they observe the water snake slowly slither to the container of unsuspecting fish. Sorry, fish, but your new home is in the belly of a water snake, not in a bowl at the dentist’s office. This container full of fish keeps the water snake satiated for an enitre week!
On Saturdays at 1 p.m. we feed our two beloved rats, Smudge and Sooty. Their meal consists of almost anything. Seriously. They feast on Greek yogurt, local and exotic fruits, veggies, seaweed, dog food, wax worms and, of course, a sweet treat for dessert. We do not intend to gross-out the public when we feed them dog food or worms. We want visitors to realize that rats are scavengers and will eat anything we eat or set out for other animals and more! Rats will thrive anywhere that supplies them with food, water and shelter- that’s why we find them in our neighborhoods.
So, next time you are visiting the Nature Museum, make sure to check the guide to find out which animal will be fed and when. The experience will surely be a treat!
Glenda GonzalezView Comments
Public Programs Coordinator
Created: 6/27/2013 Updated: 8/9/2016
After the very challenging drought year of 2012, the Butterfly Conservation Lab is up and running. Recently I traveled to far southern Indiana to continue our ongoing work with the Swamp Metalmark.
Swamp metalmark habitat in southern Indiana.
The swamp metalmark is an endangered species in Illinois. In fact, many people consider it to be extirpated (locally extinct) from the entire state. The reason the butterfly is so rare is that it inhabits an extremely rare type of wetland called a fen. Its caterpillars can only feed on the leaves of swamp thistle and tall thistle. Both grow in fens. We are attempting to re-establish swamp metalmarks to their last known home in Illinois, Bluff Spring Fen near Elgin.
In Indiana I found dozens of metalmarks from a wooded fen near the Ohio River. We brought four females into the laboratory, and set them up in special cages to lay eggs. Over the course of about a week and a half, the butterflies laid over 200 eggs. We are currently waiting for them to hatch. When they do, we will place them on leaves of swamp thistle and rear them to adulthood. We hope to have adults in August when we can release them at their new home. With a bit of luck, they will establish a new population.
Egg laying cages with female metalmarks in them.
Created: 6/26/2013 Updated: 8/9/2016
People often think of carnivorous plants as being tropical monstrosities, but many species make their homes in cold climates, and some can even be found in the Chicago region. The Museum's Biology Department took a trip several years ago to the Indiana Dunes' Pinhook Bog (open only to guided tours due to the fragility of the ecosystem) where we saw sundews, pitcher plants, and bladderworts--all species that make up for the low-nutrient peat moss they grow in by digesting insects. Combined with the rare orchids, blueberry-lined walkways, and the fact that the ground moves when you walk on it, it was one of my favorite daytrips. Volo Bog, north of Chicago, is home to such strange plants as well.
While the Venus Flytrap (Dionaea muscipula) is the most iconic carnivorous plant outside of Super Mario Brothers and Little Shop of Horrors, our local meat-eating flora have plenty to offer. Pitcher plants (Sarracenia purpurea) have leaves that form a tube that collects rainwater. The attractive red coloration draws curious creatures to the rim of the "pitcher." Occasionally an insect will fall down the slippery slopes into the pool of rainwater and be trapped, and shortly thereafter digested. But since plants lack teeth, the plant has to hire someone else to chew its food. It is said that "If you build it, they will come," and a host of invertebrates make their home in the water of the pitcher plant, forming a mini-ecosystem inside the leaves of one plant. The top predator is usually the larva of the Pitcher Plant Mosquito (Wyeomyia smithii), one of several animals which lives only inside pitcher plant puddles, and nowhere else. Please don't think we should fog the bogs, though; the pitcher plant mosquito doesn't go for people. Eventually bits of the prey are chewed, shredded, digested, and excreted by enough little bugs, bacteria, and other critters that nutrients from the victim's body become usable by the plant.
Drosera rotundifolia, the Downy Sundew, takes a different tactic. Its leaves are covered with red, tentacle-like protrusions, and coated in a sticky, sugary substance. When prey come investigating they get stuck. The tentacles then curl up around the insect, and the plant begins to exude enzymes to extract precious, nitrogen-containing compounds that are otherwise hard to come by in the sundew’s habitat. This is because in bogs, the high acidity of the peat moss and water inhibit the breakdown of organic matter, so nutrients remain locked away instead of cycling through the ecosystem as they might in more garden-variety soils. Many Drosera species have become so adapted to their conditions that they completely lack the enzyme that enables other plants to absorb nitrogen from their roots.
While our collection is small, the Museum does maintain several living examples of carnivorous plants in our Mysteries of the Marsh exhibit. As these are wetland plants, they are members of some of the most imperiled ecosystems in our region, and throughout the world. While we are tempted to think of plants as basically immobile, passive denizens of our world, carnivorous plants are some of the most obvious examples of the incredibly active role plants take in nature. Stop by and see ours, but more importantly make sure to get out into the wild, visit our protected wetlands, and spot these fantastic plants in their native environments. You won't regret it.View Comments
Created: 6/26/2013 Updated: 8/9/2016
It's a question I get asked all the time, ‘where do you get your animals from?’ There is no short answer, some are donated, some are left at our door, some are purchased, some are bred in house and some we go out and collect. For this last group we can’t just go out randomly picking up any animal we like the look of, as a scientific institution we have to have all the appropriate paperwork and permits to allow us to collect our specimens. Also we are collecting creatures for live display so we have to be very mindful of our collection methods.
This past week we were out collecting fish for our tanks in the Riverworks exhibit. Last year when we did this we had very little water to work in because of the drought, this year we had the opposite problem!
Trying to use a seine net in rushing water is a bit of a challenge to say the least and for the species we were looking for we needed to find some quieter bodies of water. It took us a while but we eventually found some good spots.
The seine net is held in place while a couple of people drive the fish forward into it.
The net is then scooped up at the last moment to secure the fish in the middle of the net. This method ensures the fish are completely unharmed in the process and also allows us a good view of everything in the net.
You never know what you are going to find in the net, which is all part of the fun. This particular scoop had a number of huge Bullfrog tadpoles in it and also a rather startled looking frog in amongst the mud and weed. They all got safely returned to the water.
We were looking for compatible species to the ones we already have on display so this haul of Top Minnows were a great addition.
Some of our cache is photographed and then returned to the river, like this beautiful Heelsplitter mussel.
We also ‘do our bit’ collecting up invasive species. Well actually, one particular invasive species, the Rusty Crayfish. An extremely popular snack for our Blanding’s Turtles!
Inspite of the high water levels we had a very successful trip, bringing home lots of new fish which will undergo a 30 day quarantine period before going on display.View Comments
Created: 6/12/2013 Updated: 8/9/2016
We are all rather fond of Harriet here at the Nature Museum. She is a very large, female Striped Knee Tarantula who has been with the institution longer than pretty much everyone. She has been here so long that I have never actually been able to find any record of where she came from or when. In spite of her somewhat intimidating appearance she is a very gentle creature and also quite a celebrity. She has featured on a blues album cover.
She has done numerous TV appearances for various local stations and she also appeared on the cover of a medical paper about treating arachnophobia.
But in between all this jet setting she is just a regular arachnid. She spends most of her time in the Istock family Look-in-Lab raising squeals from countless children.
Once in a while we will notice that she starts to slowly spin a thick web mat and then we know exactly what she is up to. She is getting ready to shed.
The first time she did this after I started working here I was alone in the lab one evening, I have to confess I had never seen a tarantula shed before so imagine my horror when I walked past her tank and she was laying upside down with all her legs in the air! Absolutely no prizes for guessing what I thought. I was so upset and spent most of that night imagining having to tell everyone that dear, sweet Harriet was no more. When I came in the next morning there appeared to be TWO tarantulas in Harriets’ cage, and they were both the right way up. By now I had begun to put two and two together, or in this case, one and one and realized what had happened, Harriet had shed. I have been here for several years now and after the trauma of that first time I made a little sign which reads ‘She’s not dead, she’s shedding!’ I have witnessed numerous Harriet sheds and each time I marvel at the process. Here is Harriet the morning after her most recent shed.
She is the one on the right of the picture! And here is her freshly shed skin, called an exuvium.
If you look closely you can see each individual hole where she carefully pulled her legs out of the old skin.
Now even if you are not keen on spiders, you have to admit, that is pretty cool!
Created: 6/11/2013 Updated: 8/10/2016
A sure sign of the change of seasons is when we in the Biology Department finally start to get out to do field work. Our Blanding’s Turtle work was severely affected last year by the drought so we had some catching up to do. First order of business, release all last years hatchlings that we had held onto due to a lack of water. We begin by blanking out their individual ID numbers to make them less conspicuous.
Then we select suitable sites with relatively shallow water, plenty of vegetation for cover and a healthy population of aquatic invertebrates for food. It is always a delightful moment when we watch these little turtles get their first taste of freedom.
After all the hatchlings were released we started doing some radio tracking. This can be a slow process as we work to follow the beeps emitted by the transmitter and home in on its location.
This time we had so much water to work in we had a problem reaching the bottom to grab the turtle when we located it. We go from one extreme to the other it seems! Unfortunately our first trail was a bust as we came up with a detached transmitter but we would far rather have this happen than find one that had obviously been removed by a predator.
We can recycle and refit these transmitters so we carefully stowed it and then set of tracking another turtle.
This one led us on a merry dance through all kinds of habitat...
...before we eventually tracked it down. It is always a great way to end a day of fieldwork by finding a large, strong, healthy turtle.
He will have his transmitter replaced and then be rereleased at the exact location he was found. Hopefully he will soon find some female turtles and start work on this year's batch of babies!
Created: 4/23/2013 Updated: 8/10/2016
When most people think of insect migration, they quite understandably think of the Monarch butterfly. It comes as a surprise to many that some species of dragonflies also migrate. In this part of the world, many of the larger and more familiar species, like Green Darners and Black Saddlebags, are among the migrants.
Swarm of migrating Green Darner (Anax junius) dragonflies outside of the Nature Museum
Migrating swarms of dragonflies have been observed in places like the shores of Lake Michigan, the Gulf Coast of Texas, and along the east coast of Mexico in places like Veracruz. Migrating swarms are sometimes observed near migrating flocks of raptors, and there is some evidence that they provide a significant nutritional resource for migrating hawks.
A saddlebags dragonfly (Tramea sp.) in Veracruz. This is one of the species that migrates.
In contrast to the Monarch migration, there still isn't much known about the dragonfly migration. Details of the timing and the ultimate destination are still unknown. Are the individuals that head south the same ones that return north?
The Cansaburro Dunes in Veracruz. Researchers are trying to determine how the Gulf Coast of Mexico figures in dragonfly migration.
In an attempt to learn more about dragonfly migration, the US Forest Service's Wings Across the Americas program has assembled a group of dragonfly experts, nongovernmental organizations, academic institutions, and federal agencies and formed the Migratory Dragonfly Partnership (MDP). The partnership includes representatives from Mexico, the United States, and Canada. Members of the partnership, including representatives from the Nature Museum, have traveled to Veracruz to observe migrating dragonflies. The partnership meets annually to discuss how best to learn more about dragonfly migration.
You can find out more about ways to help scientists learn more about dragonfly migration by visiting the Migratory Dragonfly Partnership web site.View Comments