A male bluebird perches on his nest box at the Extension office. Photo credit: Carrie Stevenson, UF IFAS Extension
“Don’t fly, Mister bluebird, I’m just walkin’ down the road. Early morning sunshine, tell me all I need to know.” These lyrics from the Allman Brothers’ song, “Blue Sky” always come to mind when I step outside our office building in the springtime. We have several bluebird houses installed on the Extension grounds, and birds have been busily building nests the last several weeks. Despite my attempts to admire from a safe distance, I inevitably disturb them and they fly off.
The Eastern Bluebird (Siala sialis) is a native species of cavity nesting bird, which covers territory from central Canada all the way south to Texas and coastal Florida. The United States is home to two other native bluebirds, the Mountain bluebird (S. currucoides), residing in high plains from Alaska to the mountain southwest, and Western bluebird (S. mexicana), which lives in drier evergreen forests on the west coast, from southern Canada to Baja Mexico. In comparison photos, the bluebird species have redder bellies on the east coast and are progressively bluer as you move west.
American bluebird species comparison. Courtesy Cornell Lab of Ornithology
A pair of bluebirds perched atop our office building. A grayer-feathered (likely female) bird can be seen on the left, near the deeper blue male on the right. Photo credit: Carrie Stevenson, UF IFAS Extension
Bluebirds’ striking color patterns make them a favorite of amateur birdwatchers and one of the easiest birds to identify in the field. Their brilliant blue is a trick of the eye, though—in reality, birds are unable to produce blue feathers. Flamingos and roseate spoonbills produce genuine pink feathers using pigments from their food (like shrimp), but bluebirds are actually gray. As described by Smithsonian wildlife biologist Scott Sillett, the blue is a “structural color” formed by the angles of sunlight and refraction from keratin, creating the illusion of a brilliant blue. I’ve always thought bluebirds seemed brighter blue on sunny, blue-sky days—turns out they probably are!
Like bluebirds, numerous native bird species are cavity-nesters. Photo credit: Carrie Stevenson, UF IFAS Extension
Bluebirds have overcome numerous threats to their populations over the last few hundred years in the United States. From habitat loss, fire ants (which attack nestlings), pesticides, and competition from introduced house sparrows and European starlings, bluebirds struggled for quite some time. Thankfully, their populations are now actually increasing and they are a “species of least concern.”
I noted about a year ago that someone in my neighborhood installed half a dozen bluebird boxes in our neighborhood park, and I’m betting that trend is multiplied exponentially around the country. Eastern bluebirds are a species of thrush, and are just one of many species that might utilize a nest box. In the wild, they are secondary cavity nesters. This means they wait for a primary cavity nester, like a woodpecker, to create a hole, then move in after it’s been abandoned. So, they are quite content to move into a prefabricated home built by humans.
A bluebird forages for insects on the ground. Photo credit: Carrie Stevenson, UF IFAS Extension
From ancient Chinese, Russian, and Native American mythology to folklore and music of the deep South, bluebirds hold a special place in the human imagination. The song and phrase “bluebird of happiness” reflects their cheery appearance and simple joy. In a quick online search of bluebird references in popular culture, I found more than 25 in the last 100 years. Something about the impossibility of a brilliant blue little bird on a spring day just feels uplifting and joyful. Even in the wistful song from the Wizard of Oz, Dorothy sings, “Somewhere over the rainbow, bluebirds fly.”
As evidenced by the scale adjacent to a quarter, the Brahminy blind snake looks more like a worm than a typical snake!
Part of the Extension job entails having friends and clientele reach out when they come across something odd while outdoors. I’ve been the recipient of random texts and emailed photos of bizarre-looking squishy finds from the beach, unusual plants, and snakes…lots and lots of snakes. So, when I got photos of a weird little worm-like critter a few months back, I wasn’t the least bit surprised. I’ve actually planned to write about this one for a while, because several people have asked me about it over the years.
While found most commonly buried in the soil, the Brahminy blind snake can get around in water as well. Photo credit: Huntley Jimenez
The Brahminy blind snake Indotyphlops braminus (also called the “Flowerpot Snake”) is considered a nonnative species due to its origin (Asia & Africa) and movement into natural areas in Florida since the 1970s. Even though it’s not from here, most biologists do not consider them “invasive,” as they do not meet the criteria of causing ecological or economic harm. In fact, I’ve only heard about people finding them in the Pensacola city limits—particularly East Hill or North Hill neighborhoods (but if you’ve seen one elsewhere, let me know!). Like many introduced insects and amphibians, the snake itself is typically transported through the landscape trade. It is small and can easily bury itself in the soil of a large tree or shrub container. These snakes can also swim, as evidenced by video from my friend of one wriggling around in her pool.
It is easy to see the snake’s deep black coloration in contrast here with the blue pool and water. Their heads and tails are almost identical. Photo credit: Huntley Jimenez
Brahminy blind snakes are members of the Typhlopidae family, which is composed of a cohort of burying snakes that mostly live in underground burrows in the soil. Spending their time in the dark, they have lost the need for vision (like cave-dwelling creatures). They have eye spots that can detect some light, but no detailed visual capability–hence the “blind” in their name. The tiny snakes are solid black (or sometimes purplish gray), about 4-6” long, and truly resemble a worm more than any snake most people are accustomed to seeing. They eat ant and termite eggs and larvae, so many folks would consider their role in the ecosystem rather useful. They are nonvenomous and do not bite, although they will push the slightly pointier posterior end of their bodies onto your skin (this won’t hurt) in a fruitless attempt at self-defense.
Interestingly, Brahminy blind snakes are all female. The species reproduces asexually through a process called parthenogenic thelytoky. The snake’s eggs can divide without a male, and offspring are genetic clones of the mother. Most species with this reproductive adaptation are insects (including the snake’s typical prey, ants), and it is rare among vertebrates. So rare, in fact, that the only vertebrates reproducing via parthenogenesis include several dozen lizards and the Brahminy blind snake. There are plenty of advantages to cutting out the “middle man” so to speak, including faster reproductive cycles and a reduction in energy expenditures related to finding a mate. However, creating genetic clones reduces population diversity, so any disease or innate vulnerability could wipe out relatives without genetic immunity.
The telltale intense growth of a witches’ broom in a pine tree. Photo credit: Keith LeFevre
Our topic today might seem better suited to late October, but it can be observed in the woods year-round. During a recent Master Naturalist class, we discussed the various species of pines that grow in northwest Florida. All seven Florida native species—longleaf, loblolly, pond, slash, shortleaf, sand, and spruce—grow in our area of the state. While they can be differentiated based on growing location, needle length, and growth pattern, one of our class members had seen something really bizarre in the local pines.
A witches’ broom in this spruce tree has resulted in a miniature version growing along its primary trunk. Photo credit: American Conifer Society
What he described was essentially an intense burst of pine needle growth at the tip of a branch. It stands out as deep green, dense, and unusual among the regular growth pattern of needles. The end result is essentially the production of a “mini-me,” a miniature copy of the normally growing tree, hanging off one of the branches. That afternoon while touring Blackwater River State Forest with a professional forester, we asked him about the strange phenomenon. He’d seen it many times and referred to it as a “witches’ broom.”
Mistletoe growing in a tree results from the same type of auxin disturbance as witches’ brooms. Photo credit: Carrie Stevenson, UF IFAS Extension
In normal tree growth, the trunk produces hormones called auxins, which control the division, expansion, and differentiation of cells. The hormones are concentrated in the growing tips of roots and shoots, and auxins maintain normal growth and keep smaller branches from overtaking the “leader.” Unusual growth occurs when the presence and concentration level of auxin is interfered with by an outside factor. The intense growth seen in these affected trees may be triggered in several ways, including pest, fungus, or mistletoe infestation, or death of terminal buds by environmental conditions. Phytoplasmas—bacteria that infect the phloem tissues—transferred by insect vectors (usually leafhoppers) are also blamed for the odd growth in some plants. Pines aren’t the only species affected; witches’ brooms can be found in other conifers like firs and junipers, nut species like hickory, pecan, and walnut, or in ashes, peaches, and elms.
The prolific growth of witches’ brooms is of great interest to horticulturists hoping to propagate dwarf varieties of the trees. This post by the American Conifer Society goes into great detail on how to “hunt”, cultivate, and encourage the growth of witches’ brooms into dwarf plants for the home landscape. Ecologically, witches’ brooms are not a huge problem for their host trees. Unless vulnerable to a massive outbreak of parasitic mistletoe, trees usually continue growing around them and live normal lifespans. The dense brush can even benefit wildlife, becoming a ready-made nest for birds or tree-dwelling mammals.
Kitchen and yard waste can be recycled into excellent soil amendments, reducing waste and saving money. Photo credit: UF IFAS Extension
When we turn the page into a new year, the motto is often “out with the old, in with the new.” But what if we actually kept the old and transformed it into something really useful? That’s exactly what happens with composting. Instead of raking up leaves, bagging them, and throwing them away, you can recycle them in a compost bin. The same goes for food waste—instead of throwing it in the trash, a significant percentage of our groceries can be repurposed. These in-house materials can produce your own high-quality potting soil and mulch, for free.
Compost bins should be located in an unobtrusive but convenient location. Photo credit: Carrie Stevenson, UF IFAS Extension
So, where to start? Logistics are important. If a compost bin is inconvenient, you won’t use it. Locate bins in a regularly traversed part of your yard, so it’s easier to make dropping the kitchen waste into a bin part of your routine. If you’ve got space, you can use a counter-top compost container or just a second trash can to hold material until it goes outside. Compost bins should be fairly close to a water source in case you need to moisten the material.
The composting demonstration area at our Extension office includes several types of bins. Photo credit: Carrie Stevenson, UF IFAS Extension
There are numerous types of bins, ranging from open-topped 3-sided wooden or concrete block piles, to hand-built bins with adjustable slats, or prefabricated plastic and metal bins and turners. If you have a lot of space, the open holding areas might work fine. But, in a neighborhood you may want a neater, more contained and covered bin.
Properly layered compost. Figure courtesy of Colorado State University Extension
The ingredients for compost are simple—you need “greens” and “browns”. “Greens” include fresh vegetables, fruit, eggshells, coffee grounds, lawn clippings, and other materials that contain nitrogen. These should be raw waste—if they’ve been cooked in oil or butter, they can go rancid in the pile, causing an odor and attracting unwanted wildlife. “Browns“ are carbon-rich materials that include dry leaves, straw, pine needles, and shredded uncolored paper. Besides oils, you’ll want to avoid meat and dairy products, dog/cat waste, and plants full of weedy seeds or recently treated with pesticides.
Finished compost can be used as a soil amendment or potting soil. Photo credit: IFAS Photography
This mix of green and brown materials provides a balance of carbon and nitrogen. You’ll layer the materials, green/brown/green/brown and add a bit of water. Once the compost starts “cooking,” microorganisms from the surrounding soil will start further breaking down the larger materials. These are the critters who put the decomposition in compost. Worms will often make their way in, adding their efforts to the material breakdown. There is a much more specific process of vermiculture (aka worm farming) if your primary interest is producing worms. Compost can take as long as you want it to—in the hot, humid Florida summers, with regular mixing you can produce compost from raw materials in as little as 2 months. In cooler weather or in passive composting, where you just dump it and leave it alone—it will take longer. Properly managed compost will not smell bad, so if there is an odor, add more “browns” or mix it. Ideas for troubleshooting compost bins can be found in Table 3 of the UF publication, “Compost Tips for the Home Gardener.”
For more information and great detail on both composting and vermiculture, check out the recorded webinar on YouTube our horticulture team hosted in October.
The Borneo camphor tree (Dryobalanops aromatica) exhibits a perfect example of crown shyness. Photo from Wikimedia commons at the Kuala Lumpur Research Forest
I spent a lot of time in my childhood lying in our backyard hammock, reading. Inevitably, I’d take a break and stare up at the tree canopy above me. We had sweetgum trees in that corner of our yard, and I’d watch squirrels chasing each other through the branches. One thing I noticed, but never really investigated, was how the highest branches spread out towards each other from the clump of trees, yet didn’t touch or overlap each other. You could nearly always see gaps of sunlight outlining the individual trees.
The canopy of mature oak trees exhibiting crown shyness. Photo credit: Carrie Stevenson, UF IFAS Extension
The term for this is “crown shyness.” As anthropomorphized as that seems, it’s an apt description for this seemingly polite growth pattern. The topmost branches of any given tree are in constant competition with each other for sunlight. Being photosynthesizers, sunlight is life. No growth can happen without the basic ingredients of sunlight, water, and carbon dioxide. So, from a tree’s perspective, there is an inherent disincentive to send growth beneath their own existing branches or those of an adjacent tree. The result of this is a botanical dance of sending branches out, neighboring trees doing the same, and multiple trees subtly angling for light. It’s like sharing an armrest on an airplane with a stranger. There’s a limited and highly desirable resource (the armrest), resulting in a (hopefully) gentle back and forth where someone either claims the space fully or you make an unspoken agreement to share it. If you do share it, it’s rare your arms touch; most of us want to keep some personal space!
Like Blue Angel jets in the diamond formation, trees will keep just a bit of sunlight between them and their neighbor. Photographed by Mass Communication Specialist 1st Class Ian Cotter. Official U.S. Navy Photograph.
While we may consciously shuffle for position in crowded public spaces, this happens for trees at a metabolic level. Evidence from an Argentinian study demonstrated that trees can “detect the presence of neighbors before being shaded by them,” using an internal sensor that detects light on the red:far red spectrum. This botanical spidey-sense comes from light-receptor proteins called phytochromes, which send out an alert that they’re close to another tree and may want to stop sending branches that direction. Growing into an adjacent tree quickly brings diminishing returns for absorbing sunlight, and it is in the tree’s best interest to keep a safe distance.
Single-species stands of pine trees exhibit crown shyness. Photo credit: Tyler Jones, UF IFAS
Crown shyness appears to be more pronounced in groves of same-species trees. Monocultures like pine plantations, or even large stands of black mangrove, exhibit the same growth patterns and timing, adapting to environmental factors the same way—particularly if they were planted or germinated at the same time. Foresters or ecologists trying to maximize the space for timber, fruit, or ecosystem restoration may want to deliberately encourage a diverse array of species, which fill in the gaps beneath the canopy and survive on less direct sunlight.
Maybe we could call it “crowd” shyness when people step back to give folks room to dance, avoiding “mechanical abrasion”! Photo credit: Cole Stevenson, University of the South
Another contributing factor to crown shyness, and perhaps one of the more crucial ones, is “mechanical abrasion.” University of Florida botanist Francis “Jack” Putz conducted research on this in Costa Rica back in the 80’s, which is still frequently cited in more recent publications. His team’s findings showed that crown shyness was “positively correlated with the distance pairs of trees adjacent to the gap swayed in the wind.” When tree branches physically bumped into one another on a regular basis, they kept their distance to prevent bud, bloom, and branch tip damage. For this scenario, imagine someone dancing enthusiastically in the middle of a big music festival—if there’s room, people will often spread out. The more the person flails, the more space you give them. If they’re just minimally swaying back and forth, you might stand closer. Putz, et. al observed this same principle in the coastal mangrove forests—more flexible branches adjacent to one another gave each other more space, while those with “stiff crowns” that couldn’t move much grew closer together.
When space opens up due to the loss of a neighboring tree or branch, the infusion of sunlight/fuel spurs a tree to send energy quickly to gain the advantage over adjacent trees. Tree species vary in their capability and success in doing this. An earlier article on pioneer species (the first to occupy a newly open space) and the process of succession sheds more light on this natural phenomenon. In a mature forest, the end result is a balanced mosaic of tree branches reaching out and nearly touching one another, but leaving each other space to grow.
