Avian generations in the making – part 2A: nesting and man-made construction

Hi folks — today I’d like to share with you some of my observations on the second part of avian reproduction — the process in which birds make a nest and lay eggs. (By the way, if you look up “bird nesting” on the Internet, the search will lead you to a human activity: a shared custody arrangement where children reside in one house and the parents take turns living there with them. In the bird world, some avian parents will actually share a home, such as this very old and enormous sociable weaver nest (Philetairus socius) that I saw in Namibia.)

Females of a few species will deposit their eggs in the nests of another, such as some cuckoos and brown-headed cowbirds (Molothrus ater). Some people dislike cowbirds intensely because of their nest parasitism (the cowbird baby will hatch first and eat all the food or perhaps get rid of the other eggs or babies). I figure that this is how the cowbird evolved – it didn’t make a choice to wipe out other species so I can’t blame or hate the bird for it. But the cowbirds do appear to pick on particular species as involuntary “foster parents” and this may be affecting the success of the other species’ reproduction.

There are two general broad categories of bird nests – those located in or on man-made objects such as nest boxes, atop downspouts, in vehicles, in plant pots and other places and those constructed by birds in trees, shrubs and on the ground (i.e., the natural environment which I will discuss in the next blog so this doesn’t get too long!). When birds make a nest in a “human area”, people will often try to accommodate them, not using the object or vehicle or making the space safer. For example, when American robins (Turdus migratorius) put a nest on one of my downspouts, I covered the rainwater container underneath it so the fledglings wouldn’t drown when they leapt to freedom. (I did it just in time, too!)

Swallows and phoebes will also use human constructions as places to situate their homes. The cliff swallows (Petrochelidon pyrrhonota) gather up mud, making countless trips to wad up small balls of the material to carry back to a place like this pier at Cane Creek Reservoir where they line up their nests in a row.

   

Barn swallows (Hirundo rustica) locate their nests inside, using rafters to place a nest; they may end up sharing space with paper wasps and organ pipe mud dauber wasps (Trypoxylon politum), which doesn’t seem to bother them.

The Eastern phoebe (Sayornis phoebe) may use an inside corner of a patio overhang as a site that is conveniently accessible from outside.

Purple martins (Progne subis) living east of the Rocky Mountains almost exclusively nest in homes provided by people. The hanging gourd nests can be seen in fields but nowadays other types of plastic constructions are also used.

    

In order to attract barn owls (Tyto alba) back to areas where many traditional barns have been razed, people are also placing special boxes in fields with plenty of open space in front of them so that the owls will have a hunting territory adjacent to their front door. Made of heavy plastic, these boxes may be monitored by organized groups in an effort to document their use.

   

At the Mason Farm Biological Reserve, an eagle scout project involved bringing in cranes to attach very large nest boxes to the tops of trees for barred owls (Strix varia) – so far, I have only seen Eastern gray squirrels making use of these nests.

And then there are the nest boxes that people put up to attract Eastern bluebirds (Sialia sialis), brown-headed nuthatches (Sitta pusilla) and screech owls. In my yard, other birds use these boxes, too, including the Carolina chickadees (Poecile carolinensis) such as my one-legged,  banded friend Chantal, Carolina wrens (Thryothorus ludovicianus) who may puzzle about how to get a long twig into the box and house wrens (Troglodytes aedon), who pile up twigs in a rather untidy stack inside the box.

   

   

Chickadees construct lovely mossy nests lined with hair, fur or plant fibers.

      

The nuthatches have nests with bark strips.

    

Sometimes people will intervene when a nest is in danger. A Carolina wren put her nest into a boat at Cane Creek Reservoir that was rented out to people and keeping the nest there was not a good option as she would be missing her nest for hours when the boat was gone. The land manager was so kind as to relocate the nest into a tree right in front of the boat’s resting place; unfortunately, inclement weather caused the nest to dislodge that evening.

   

Another danger may also threaten the birds and their nests – predators. A friend and I found it unusual to see a tree swallow (Tachycineta bicolor) putting a nest in a bluebird box on the edges of a farm. Several days later, we saw a black rat snake (Pantherophis obsoletus) peering out of the box and the swallows were nowhere to be seen.

   

If you can manage to mount your boxes on poles rather than trees, put both squirrel and raccoon baffles on them and also place them away from overhanging branches, they should stay relatively safe from the squirrels, snakes and raccoons. Next up: birds’ nests with no human connections.

 

 

Pulling privet, banishing buckthorn and mimicking Mother Nature

The (somewhat) varied life of a Mason Farm Biological Reserve volunteer

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Today marks the third anniversary for my work as a Green Dragon – volunteers who help maintain the 367-acre Mason Farm Biological Reserve in Chapel Hill, North Carolina. On Tuesdays, a small group gathers to carry out tasks assigned by Neville, who is the Land Manager for this and two other preserves managed by the North Carolina Botanical Garden/UNC.

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Neville, string-trimming Japanese stiltgrass (Microstegium vimineum)

winter-wren-i77a8901-maria-de-bruynWhile we work, we can listen to the songs and calls of lovely birds, like the winter wren (Troglodytes hiemalis), and if we’re lucky, we can see wildlife like painted turtles, raccoons, opossums and coyotes (Canis latrans).

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Being outdoors and helping keep the Reserve a peaceful and beautiful area for research and enjoyment of the natural world provides me with a feeling of civic contribution, as well as satisfaction, chances for discovery and learning, and well-being. So I’d like to share with you a bit of what we do in a lengthier blog than usual.

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wisteria-cutting-img_0427-maria-de-bruyn-resOne of our major tasks is helping make a dent in the eradication process for invasive plants. Some have found their way to the Reserve through natural dispersal mechanisms (seeds carried by the wind and wildlife), while others were unfortunately introduced by humans who didn’t know at the time just how destructive the plants would become in overshadowing native vegetation. Cutting down Chinese and Japanese wisteria vines (Wisteria sinensis, W. floribunda) is a recurrent job.

Some invasives are really beautiful and it’s easy to see why they are still sold in some garden shops, like oriental bittersweet (Celastrus orbiculatus) and porcelain berry (Ampelopsis glandulosa); they are really attractive plants – nevertheless, we remove them when feasible. Autumn and thorny olive (Elaeagnus umbellata and E. pungens) are two others that grow as vines or shrubs.

oriental-bittersweet-8-oriental-bittersweet-img_5343m-de-bruyn-signed   porcelainberry-img_0739-2maria-de-bruyn

buckthorn-i77a2455-maria-de-bruyn-signed-resAnother botanical foe is buckthorn (Rhamnus species), a shrub which can grow into a small tree when unchecked. It has nasty thorns which can pierce clothing and shoes and when it gets older and larger, a weed wrench and extra manpower may be needed to get it out of the ground. On the other hand, pulling up the “baby” buckthorns, especially after rain, can be much easier, though unkind work for your back.

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Volunteer Pete wields a weed wrench; the small buckthorns can be pulled by hand

marbled-salamander-img_3320maria-de-bruyn-resWhen digging holes into some areas, you may come upon salamanders – this female marbled salamander (Ambystoma opacum) was guarding her eggs when we uncovered her (and quickly covered her again).

The buckthorn produces prolific black berries which are a great favorite of the cedar waxwings (Bombycilla cedrorum) – flocks will descend to enjoy the sweet treat.

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The cedar waxwings also really like privet (Ligustrum sinense and L. japonicum), which produces numerous black berries a little smaller than the buckthorn. The privet also produces many offspring but when they are very young, they are quite easy to pull up. The privets that grow into trees, however, pose the same challenges as the large buckthorns, calling for multiplied manpower to extract them from the ground and resulting in exhaltation when success is achieved.

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While working on invasive eradication, we often come upon smaller wildlife, like American toads (Anaxyrus americanus, formerly Bufo americanus), bullfrogs (Lithobates catesbeianus), green and gray tree frogs (Hyla cinereal and H. chrysoscelis/versicolor), spring peepers (Pseudacris crucifer) and rat snakes (Pantherophis obsoletus).

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The many brush piles dotting the landscape in the Reserve, both in wooded areas and fields, are the result of our labors – providing birds and small animals with ready-made homes and hiding places.

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Volunteer Giles and Neville pile up privet and buckthorn

A second major task is planting native plants in various areas of the Reserve – seedlings and young plants are provided by the Botanical Garden and Land Manager and may include flowering species such as Hibiscus and cardinal flowers (Lobelia cardinalis), fruiting shrubs like common elderberry (Sambucus nigra Canadensis), and varied grasses.

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bill-resting-sore-back-img_0284maria-de-bruyn-signedWhen we do this in summer, the temperatures can get quite high early in the day; water breaks are welcome, as shown by Mason Farm Green Dragon supreme – Bill, who has been volunteering since 2004!

We put in flags to mark the new plantings in case they will need some watering to thrive. When the weather is hotter and drier, watering takes place right away to give the young vegetation a better chance at survival. It’s a real pleasure to see the plants take hold and flower!

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flame-i77a0237-maria-de-bruyn-resSome plants are fire-dependent, meaning their environment must be burned with some regularity if they are to survive and thrive.

Prescribed burns are therefore done at Mason Farm to mimic the natural fires which took place centuries ago before development took over many areas. Woods and fields are burned every few years and great attention is paid to the weather, taking care that no high winds are predicted that could carry embers far away to start fires in unwanted areas. The Green Dragons helped clear fire lines last week for a recent burn – raking away leaves and twigs and bark from areas where the fire will normally die out.

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neville-i77a0232-maria-de-bruyn-resMembers of the fire team receive instructions on their roles – the fire starters ignite the leaves and grasses in stages, pausing to see how fast the fire is moving and how the wind is blowing.

 

 

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Several people will serve as spotters, watching the fire lines to ensure that any escaping embers are put out and some team members clear areas around trees and snags that will be protected against burning (e.g., because they provide homes for woodpeckers).

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Where the leaf litter is not 100% dry, some areas will burn and others will remain untouched.

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Dry grasses can catch quickly and the spreading fire generates intense heat as the flames spread rapidly across a field.

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broad-tipped-conehead-katydid-neoconocephalus-triops-img_1403-maria-de-bruyn-resMy concern is always that not all animals will make it out in time. Fellow volunteer Giles spotted a broad-tipped conehead katydid (Neoconocephalus triops), which he carried to a safe spot. I hope that the Eastern box turtles (Terrapene carolina carolina) have dug down deeply enough to be unharmed by the spreading fire. We saw grasshoppers and bugs fleeing the field being burned this past week and I was happy to see a pair of hispid cotton rats (Sigmodon hispidus) rush out.

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After the fire is mostly burned out, the team walks the edges to tamp out still burning places. The next day, the woods and field look mostly gray, black and sere but experience has taught me that in a few weeks they will begin turning green again.

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There is one more task we carry out which is less frequent but also important – aiding in construction and some clean-up in the Reserve. When funding was received for a boardwalk to make a bog area more accessible after rain, volunteers associated with the Botanical Garden and New Hope Audubon Society as well as Green Dragons built the sections of the board walk, transported them to the site and installed them.

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flooding-img_1936-maria-de-bruyn-resVisitors were very happy with the new walkway but it turned out that the flooding which occurs when Morgan Creek overflows its banks with heavy rains can sometimes be strong enough to lift up boardwalk sections, necessitating repairs. When funds are available, a new solution will be sought to hold the boardwalk more permanently in place.

 

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The researchers who make “temporary” structures when conducting their studies (e.g., bird blinds, platforms, etc.) unfortunately do not always remove these when their research is done. When time permits, we have helped clear away some of this garbage. We also helped repair a sign and the entry road and parking lot after flooding.

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Our volunteer crew is usually a small group of retired persons and a couple students (2-5 people). We’d love to have more people join us so we could get more done and have more input for our conversations covering a range of topics such as botany, geology, wildlife observation, music, sports, travel and current events. The volunteer time of Tuesday mornings unfortunately rules out people who have jobs requiring their presence there on weekdays but we remain hopeful that new volunteers will join us. If you live in the local area and are interested, contact the volunteer coordinator at the NC Botanical Garden!