Helping birds build nests in my yard

Inside view of the house wren's dummy nest. I love the wren-shaped hollow in the middle!

For the second spring in a row, a male house wren used my window birdhouse to hold one of the dummy nests he showed his mate. House wrens apparently make several dummy nests for the female to choose from. Just like last year, though, she chose a different location to actually lay her eggs. Phooey! So that started me wondering whether there was anything I could do to improve the chances she might actually use my birdhouse next year. Would she prefer a different location? Or should I make better materials available for the male to use?
 

Outside view of the nest. Both years, twigs or grass stems stuck out of the entrance. I'm not sure if this is typical for the species, or just my individual bird.

As I researched house wrens’ nest preferences, I realized I could also explore other neighborhood birds’ nesting requirements. If I added more possible nest sites to my yard, like birdhouses and large bushes, and provided appropriate nesting materials, maybe I could convince even more species to nest in or near my wild back yard!

Cornell Lab of Ornithology has lots of information on birds, from how to ID them to their habitat and life histories. I looked for the species I know visit my yard in the summertime, figuring they’d be my likeliest nesters.

Anyway, my backyard birds are either cavity nesters, or branch nesters. Birdhouses can attract cavity nesters, since they look close enough to the tree holes the birds normally use. On the other hand, birds that normally build their nest on open branches aren’t likely to use a bird house. But of course birds don’t always go by the book. An ornithologist friend of mine discovered a house wren pair that was raising their young not in a cavity nest, but in an open cup nest built on some branches! Weirdos.

In doing my research, I also found that www.Nestwatch.org has downloadable plans to make birdboxes for various species too. I’m definitely adding "building birdhouses" to my project list. Maybe something to work on this winter? Nestwatch also lists helpful features of good birdhouses to guide aspiring nest hosts like me.

Cavity Nesters

A lot of birds like to nest in the hollows of dead or dying trees. Whether they add materials to the cavity, or just use the soft decayed wood that’s already there, varies by species. These birds are one of the main reasons for leaving dead trees standing in your yard when possible, rather than cutting them all the way to the ground. But if you don't have any dead or hollow trees in your yard, birdhouses make a reasonable alternative!

·       Carolina Chickadee—moss, bark strips, and hair

·       Tufted Titmouse—leaves, moss, grasses, bark strips, soft fur and hair

·       White-breasted Nuthatch—fur, bark strips or shreds, grass, feathers

·       Downy Woodpecker—wood chips

·       Red-bellied Woodpecker—wood chips

·       House Wren—twigs, feathers, grasses, hair, snakeskin

·       Carolina Wren—bark strips, grasses, leaves, pine needles, hair, straw, feathers, shed snakeskin

·       

Branch Nesters

Other birds prefer to build nests on the branches of trees or shrubs, or even under the overhang of building eaves and bridges. While you wouldn’t build a birdhouse for these species, you can still provide materials for them to use. On winter hikes, I enjoy spotting the empty nests that had been hidden during the summer.

·       Northern Cardinal—branch fork in a shrub. Uses twigs, leaves, bark, grasses.

·       Blue Jay—branch fork in a tree. Uses twigs, grass.

·       Mourning Dove—branch, also frequently nests in gutters, eaves, flowerpots. Uses twigs, grass, and pine needles.

·       House Finch—tree branch, also structures like hanging flowerpots, vents, & streetlamps. Uses fine stems, leaves, twigs, and feathers.

·       Eastern Goldfinch—branches in a shrub. Uses spider silk, plant fibers, and fluff from seeds like dandelion and thistle.

·       Eastern Phoebe—under the overhang of building eaves or under bridges, especially near running water. Uses mud, moss, leaves, grass, and animal hair.

·       Northern Mockingbird—Shrubs. Uses twigs, grasses, rootlets, and leaves.

·       American Robin—horizontal tree branch, or on/under structures like eaves, gutters, and light fixtures. Uses twigs, grass, feathers, and mud.

You might have seen suggestions to provide bits of string and yarn or even dryer lint for nesting birds. When I was a kid, we often draped scraps of yarn on bushes outside, in hopes that birds would weave them into their nests. But it turns out string and lint aren't actually safe or useful for the birds. Dryer lint turns hard and crumbly once it’s gotten wet, rather than staying soft or helping hold the nest together. And even short bits of yarn can tangle around baby birds’ feet and toes. I don't want to hurt or endanger the baby birds in my yard, so I won't be using yard scraps for my nest material kits.

Some of the nest materials I listed are already available in my yard, like the drifts of dry leaves that collect in corners. Others I will tuck into clean, empty suet feeders to make little supply stations for inquisitive birds, as described here. I don't put out suet in the summertime, so the suet cages are available for use. Fat can go rancid in the Maryland heat, and softened fat could also foul a bird's feathers. So next spring, I'll stuff the cleaned cages with materials like bark strips, dry grasses, plant fluff and odd feathers. I have lots of milkweed plants in my yard, and plan to collect some of their seed fluff when the pods ripen this fall.

In the long term, I also want to add more shrubs and bushes to my property. I have a back yard that's mostly underutilized in terms of gardening-- it has a few trees that were already there when I moved in, but I haven't changed things very much beyond adding the log pile. The back is partly to mostly shady, so isn't conducive to most pollinator plantings. But birds don't need the sun quite as much as bees and butterflies and flowers do. So I might focus my back yard landscaping on bird habitat. Stay tuned! 

Do you have any birds nesting nearby this year? Have you discovered birds nesting in odd places? I'd love to hear about them in the comments!

The wren mostly used twigs this year, but also some tall grasses complete with seeds. Handy snacks, perhaps?

Could Raising Captive Monarchs Mess Up Migration?

A late-season male Monarch butterfly nectars on my New York Asters

As you may have heard, alarming new research about raising Monarch butterflies was published recently, by Ayşe Tenger-Trolander, Wei Lu, Michelle Noyes, and Marcus R. Kronforst. Their study found that indoor-reared fifth-generation Monarch butterflies did not display southward flight in tests, which means they wouldn't migrate properly. Uh-oh!

I haven't been able to access the entire article yet, just the abstract linked above, and a write-up in Science. But even those limited sources give me concern about my techniques in raising Monarchs. The researchers raised both commercially-bred monarch caterpillars and wild-caught. Although they used the caterpillar generation that's supposed to migrate, both groups  had neither the elongated wings of migratory individuals, nor showed predominantly southward flight under test conditions. (They attached the mature butterflies to poles in the experiment, so they could observe which directions each butterfly would head. Previous research has shown that in these conditions, migratory monarchs reliably try to fly southward.) The scientists even raised some wild individuals outdoors until the point of pupation, and found that if those individuals eclosed indoors, they too seemed to have lost the tendency to migrate!

Two of my Monarch chrysalids last year, raised indoors & then released after eclosing.

Not unexpectedly, this has thrown the butterfly-raising community into a bit of a tither. Are we actually exacerbating the threats to monarch migration as we try to help? When our efforts include raising the caterpillars indoors, especially the migratory generation, it looks like maybe so.

From what I'm seeing on various email groups, Twitter, and Facebook, many caterpillar hobbyists and citizen scientists are distraught. Should we change our habits and maybe abandon the hobby of raising monarchs?

Honestly, I've already been somewhat concerned about my butterfly raising. This isn't the first study to indicate we might be doing more harm than good, for one thing. I had thought, though, that the main problem was using captive-bred caterpillars, like classrooms might when they mail-order caterpillars from who knows where in order to have them on time for the lesson plan. Since I only raise wild-caught individuals (whether starting as egg or already-hatched caterpillar), I hoped I wasn't doing too much damage.

But another effect of captive-raising caterpillars can be to allow weak genes to survive and get passed along. Since I'm protecting the caterpillars from natural stresses, a trait that would have made an individual less likely to survive isn't actually a problem, and may end up expressed in the next generation too. Especially if I raise every monarch caterpillar I can find, I might still be making my local population less fit. Now this new research just adds more support to reconsidering my actions.

This Monarch caterpillar lived its entire life outdoors at Brookside Gardens, where I found it getting ready to pupate.

I can't speak to what anybody else will or should do, of course, but here are ways I'm planning to change my caterpillar husbandry:

• In general, I will collect and rear no more than 50% of the eggs and/or caterpillars that I find in my garden, of each species. The rest I'll leave wild and unbothered, to fend for themselves. (This also means I'm not reducing the amount of available food for hungry birds!)
• For monarchs in particular, I will rear no more than two caterpillars per generation for the first four generations each year.
• Once the migratory generation's eggs are laid, starting around August in my area, I won't raise any monarchs. 

I also considered trying to create an outdoor setup for raising monarch caterpillars, rather than keeping them in my office indoors. That will take quite a bit more planning, however, so stay tuned.

Another idea was to raise monarchs indoors until they look ready to pupate. Then I could move them outside while they pupate and later eclose. Although I'm not sure exactly what the pupa get from being outdoors, the new research does indicate it's a crucial factor in triggering migration: "In fact, merely eclosing indoors after an otherwise complete lifecycle outdoors was enough to disrupt southern orientation."

I'm not changing how I raise Black Swallowtail caterpillars, or other non-migratory species, as much as I'm changing my treatment of monarchs. I'm definitely reducing how many I raise, going by the 50% rule above. Also, if I find a single egg or caterpillar on any day, I won't bring that in at all. I know I still might be changing something essential in these butterflies by raising them in the protected environment of my office. However, I do call them "pets" sometimes because I know they may not be the same as totally wild individuals. I guess they're kind of half-wild; I do release them as soon as they eclose. I always hope they make my local population larger, going on to mate and lay more eggs that lead to more caterpillars. This summer I'll keep thinking about whether I feel comfortable bringing them inside any more.

As much as I love watching the caterpillars up close, am I being selfish by bringing them inside?

Do you raise butterflies indoors, or have you ever? What do you think about this new research? I'd love to hear your thoughts, whether you plan to stop raising butterflies at all or keep on caring for them like you always have.  Perhaps you even have a totally different method of raising caterpillars than I do. Whatever the case, please leave a comment below to keep the conversation going!

The Saga of a Soggy Caterpillar

How long can you hold your breath? The current human record for holding one's breath is 24 minutes and three seconds, by professional diver Aleix Segura Vendrell. Wow! I can't hold mine for much longer than a minute. But even Mr. Vendrell's effort pales in comparison to insects-- some insects actually can hold their breath (that is, not inhale) for days! According to this article in Annals of the Entomological Society of America, larvae of various Cicindela Tiger Beetles can survive being submerged in hypoxic (low oxygen) water for between 60 and 120 hours. Wow.

But the tiger beetles have evolved that ability to survive, since their larvae burrow into sand which is liable to flood for days. What about solely terrestrial insects? Like, say, butterflies and their larvae? Turns out even they can survive a bit of dousing, or at least one of my caterpillars this summer did.

First instar Black Swallowtails are barely larger than the type on a park brochure!

One day I came home and checked on a day-old Black Swallowtail caterpillar like the one shown above, only to find that it had slipped under the surface of the water reservoir instead of staying on its dill sprig. (Note to self: watch out with tiny caterpillars and tiny dill sprigs!) My heart nearly stopped. I had even watched this egg being laid by the butterfly right beside me as I weeded the garden, so I was especially attached to this particular caterpillar. I had no idea how long the caterpillar had been underwater-- it could have happened hours ago. But just in case, I fished out the little body. How on earth do you give CPR to a millimeters-long caterpillar? For that matter, I don't know if you even could  do CPR for caterpillars. Like other insects, they breathe through multiple openings, called spiracles, along their sides. Mouth-to-mouth wouldn't exactly work.

Out of desperation, I just blew gently on the soggy, limp little black caterpillar. And it started to move! As the line from Monty Python and the Holy Grail goes, "I'm not dead yet!" I transferred the caterpillar carefully to a fresh sprig of dill, and kept it under close observation for a few days.

Once it was clear my caterpillar was out of danger, I became curious. Could caterpillars hold their breath at will? How, and for how long? This question sent me down a rabbit hole of research. I haven't yet found information specific to caterpillars, but did find one intriguing paper from 2005: "Insects breathe discontinuously to avoid oxygen toxicity," by Stefan K. Hetz and Timothy J. Bradley (Nature 433, 516-519). The researchers suggested that unlike us continual-breathers, insects keep their spiracles closed most of the time, opening them briefly and infrequently to release carbon dioxide and inhale just enough oxygen. The original paper is behind a paywall, but it's summarized in this article at LiveScience. So my caterpillar didn't hold its breath, exactly, so much as just keep its spiracles closed and use the oxygen already in its system, while it was underwater. Pretty cool!

Over the next few weeks, the caterpillar munched down all the dill I could provide, and grew quite normally. Despite the underwater episode, it actually turned out to be one of my largest caterpillars ever. Now, I don't actually measure my caterpillars, either their length or their overall weight-- I take a fairly hands-off approach most of the time. But just eyeballing, it seemed larger  than the other caterpillars I had raised a few days before.

So fat and happy! And no longer soggy in the least.

It pupated not long after I took this photo, and then successfully eclosed yesterday: a healthy female. Even my husband remarked that the butterfly seemed larger than usual, corresponding with its large larval size. After a few minutes of warming up in the sunshine, off it fluttered. Hooray!

The freshly eclosed Black Swallowtail, ready to fly off into my yard.

So moral of this story is: don't give up, even if your caterpillar falls into the water. They're amazingly resilient. No wonder they and other insects are predicted to take over the world someday!

The Best Time To Hang a New Birdfeeder

No birds yet! The dropping level of seeds indicates the squirrels have visited, however.

A common frustration with wild bird feeding is how long it takes birds to notice (and visit) a new feeder. For those first several days, when the only attention you’ve attracted is from the neighborhood squirrels, it’s all too easy to wonder if the birds hold some grudge against you, or if you did something wrong.

In fact, this is totally normal. It can take a while for birds to even notice something new, and then longer before they feel safe venturing closer. Annoying, but typical. When I first put my back yard feeders up, mentioned in this post, it was almost three weeks before I saw many birds on them!

However, there is one trick you can use to get faster attention to a new feeder. The secret is low competition, great advertising, and honestly, a little bit of luck-- because the absolute best time to hang a new feeder is right after a snowstorm.

When fresh snow blankets the ground, the birds’ usual sources of food will be covered up as well. Without their favorite spots competing with your new feeders, the birds should be quicker to try something unfamiliar, to say nothing of desperate for something to eat.

Not much to eat here!

The snow also gives you a perfect opportunity to advertise your new feeder. First, pack down the snow under your feeder by stomping around, or smushing it down with something flat. (Otherwise the seed will just sink into the soft snow.) Once you have a nice dense layer, sprinkle plenty of black oil sunflower seeds on the packed snow. The dark seed contrasting with the white snow should catch the attention of birds searching for food, hopefully leading to your first feathered customers.

These days when I scatter seed after a snowfall, I have birds within minutes! 

You don't need a huge snowstorm for this method to work. Here the snow was only a couple inches deep.

To attract even more birds to your yard in the winter, you could also put out a heated birdbath. The birds' usual water sources are likely frozen or covered with snow, so a source of fresh water will be very welcome to local birds. You might even attract species that don't eat bird seed, like bluebirds or robins. You can buy a bird bath heater for about $40, or you could put out a pan of fresh water each morning just until it freezes, then bring it back inside to thaw. I recently ordered a heater for my birdbath, so while it didn’t arrive in time for our first snowstorm, I should have it in use before the end of the winter. (Stay tuned!)

In order to survive, birds need the right combination of food, water, and shelter. The more of these that birds can find in your yard, the more likely they’ll show up.  By hanging a new feeder right after a snowstorm, when food is desperately needed, you’ll likely get a faster response than when natural foods are easy to find. Win-win!

I hope you enjoy watching birds in your yard this winter, along with any other animals that might show up, like squirrels, rabbits, deer, and even foxes. I’d love to hear about what you see!

Once the birds are drawn to your yard, they'll soon explore your feeders as well. This Song Sparrow looks pretty cozy as more snow falls.

Wildlife Garden Tools: Native Plant Finders

Want to help wildlife in your yard? Try growing the plants they’re already used to in the wild, also known as native plants. For gardeners who aren’t sure how to start building backyard habitat, there are lots of native plant resources online. I’ve compiled a few that I find useful. Whether you’re hoping to attract birds, butterflies, or bees, these sites can help you figure out what to grow.

This Carpenter Bee picked up both pollen and nectar from the Swamp Milkweed in my yard

The National Wildlife Federation's plant finder has you enter your zip code to see a list of native plants for your area, ranked by how many caterpillar species (butterflies as well as moths) each plant supports. Since most birds rely on caterpillars to feed their babies, this site can also help you support birds as well as butterflies and moths. Yum!

The Audubon Society also offers a native plant finder that is based on your zip code. You’ll get a list of plants for your area that are easy to grow and should be available at native plant nurseries. Beside each plant’s description you’ll also see thumbnails of the birds it attracts. Audubon also lists nearby nurseries (and their web sites). identifying types of birds that may be attracted to each suggested plant, and basic appearance and culture needs for each plant. There’s even a “Buy Now” button for each plant, with options of either “buy local” (nearby Audubon chapters that offer plant services, nearby native plant nurseries) or “buy on Amazon.” Before you click “buy on Amazon,” you can follow a link to read tips about buying plants online.

Monarchs love late-booming flowers like these asters.

The Lady Bird Johnson Wildflower Center in Texas hosts helpful resources about native plants on its web site. You can find information about commercially available plants that are native to your state, explore plants that are especially good for bees or for hummingbirds, and even find a list of nurseries that carry native plants. You’re supposed to be able to narrow that supplier list by state or zip code, but that tool seemed broken as I write this. A workaround is just to click “show all suppliers,” and scan the list to find nurseries or seed sources that are near you.

The Mt. Cuba Center, in Delaware, is a native plants botanic garden. While the garden is closed during the winter, the web site has lots of information about native plants for the Mid-Atlantic area. It won’t help you much if you live in another part of the country, but the site does give you much more detail about the specific plants and their culture & habitat needs than National Wildlife Federation’s tool. You can also refine the list by plant type, amount of sun needed, foliage type, and/or flower color, to find just the right plant for your garden.

Lastly, the Habitat Network and Project Yardmap are great resources that unfortunately have just lost funding. All of the articles are still available, and will eventually be moved over to Cornell Lab of Ornithology’s All About Birds web site. Until January 31, 2019, you can still find resources at http://content.yardmap.org/learn/, such as pictures of birds in your area sorted by what kind of food they like. You can click individual birds to find out their specific plant preferences and other habitat needs. 

Goldfinches love seed-bearing flowers like this sunflower. Coneflowers are also popular.

Of course, even better than online plant finders like these would be personal observation and experience. If you’re willing to wait a year or two before deciding, then you could try to find the plants on your list in the wild. That way you can see how it looks through all seasons, and observe how many birds, butterflies, or bees visit.

But you probably don’t want to wait that long. (I know I usually don’t!) So your next best choice would be to ask for advice and impressions from folks who have long experience with the plant. If you don’t have neighbors like this, you could try social media—there are tons of gardeners online who are happy to share our knowledge. You could also ask me in the comments below!

Whatever you choose to do, and whatever plants you select, have fun! Even “failed” gardening still gets us outside and brings us more in touch with nature. So in that sense, there’s really no 100% wrong plant selection.  Just keep planting more, you’ll eventually find the ones that work best.

Achievement Unlocked: My First Mega!

How did you do on your goals for 2018? I managed to complete one of mine in the last few weeks of the year: to spot (and log on eBird) at least 150 different bird species. Yay! My 150th bird wasn’t exactly ordinary, either: a species that’s only been seen in the US one other time. That’s what birders call a mega rarity, or mega. Although I’ve been birding for several decades now, this is the first mega I’ve ever chased.

I’ve seen locally rare birds before, like the Snowy Owls that occasionally make their way south to the mid-Atlantic area. But megas are another level. The American Birding Association (ABA) classifies birds in six levels, or codes, of rarity for the U.S. and Canada.

• Codes 1 and 2: Regularly occurring North American birds.
• Code 1 species are widespread and usually numerous.
• Code 2 species are harder to find because their range is restricted, there are fewer of them, or they are very secretive.
• Code 3: Rare. These species occur in very low number, but show up annually in the ABA checklist area. Some are visitors, others are year-round residents.
• Code 4: Casual. These species are usually not observed every year, but have been recorded six or more times, including three or more in the past 30 years. That way a pattern can be discerned.
• Code 5: Accidental. These are species that have been recorded five or fewer times in the ABA area, or have fewer than three records in the past 30 years. Because of the infrequency of sightings, birds in this group don’t seem to have a pattern of when/why they show up in our area.
• Code 6: Cannot be found. Species in this group are probably or actually extinct or extirpated from the ABA area, or else all survivors are in captivity.

Of course, each bird species has its own range and preferred habitat, and that may not include all of the ABA territory. So a lot of code 1 or code 2 birds would be exceedingly rare outside of their normal territory, for example finding a code 1 Juniper Titmouse here in suburban Maryland. Generally, though, the higher code birds are harder to find.

The bird that put me at 150 species for the year, a Great Black Hawk (Buteogallus urubitinga), is in the coveted code 5 group. The first time one was seen in the US was in April, 2018, on South Padre Island in Texas. After that, one was found in Maine in August, then seen sporadically until it showed up in Portland in late November. At that point it settled into Deering Oaks Park, a small city park with a multitude of very well-fed squirrels. It even turns out that the Texas and Maine birds are the same individual, with an identical pattern of flecks on the underside of the bird’s wings, as described in BirdWatching.  Now that’s one far-traveling bird—from its normal range in central or South America to Texas, and then all the way up to Maine!

I know several birders who drove from my area all the way to Maine just for the chance to see this hawk. Seeing the bird wasn’t my primary reason for going to Portland this winter, though—I was heading up to visit family for Christmas.

Our trip almost didn’t happen, though. A week before we were supposed to drive up, I developed an extremely painful kidney infection. Ow! I had to go to urgent care while visiting my mom in Florida, and got put on some heavy-duty antibiotics. They couldn’t work fast enough for our next trip to Maine, though, I still wasn’t well enough a week later, when we had planned to drive up. I knew I was truly sick when even the thought of seeing such a rare bird wasn’t tempting.

But we did make it to Maine, only a few days late. I owe a huge thanks to my wonderful husband for doing all of the driving. Thanks, hon!

Anyway, we were busy with family celebrations all day on Christmas, but I kept checking the Cumberland county rare bird alerts, following other birders’ accounts of their sightings and hoping the hawk would still be there the next day.

My first try for the bird was not successful. Victor, my sister Cory, and I drove over to Deering Oaks about 10:00 am, late by most birding standards. We wandered the park, peering up into every tree and shrub, but no luck. A few other groups of birders were there too, some with really high-powered scopes and cameras. One birder pointed out a Red-tailed Hawk in some nearby trees, but nobody had found the Great Black Hawk. We decided to go elsewhere, and maybe try for the hawk again later.

I love that the city posted these signs all over the park, helping ensure folks treated the bird respectfully. The numbers to call in case you observed the hawk in distress are a nice touch too.

The second time we looked for the bird, after some lunch with my dad, luck was finally in our favor. The hawk had been found by others by the time we got to the park. It was easy to spot, by the huge cluster of birders admiring it from a short distance away. The hawk was perched in a tree beside the main road, and seemed totally unfazed by cars driving past mere feet away. A jogger even ran right under its perch, and the hawk seemed only barely curious. It probably had just eaten, and was still feeling the food coma. (Who knew birds got food comas like we do?)

Unfortunately, I had left my camera at home in Maryland. Arrgh! However, a very kind birder who was allowing passersby to look at the bird through his scope, also let me take a hasty digiscoped photo with my cell phone. It’s not the greatest, but hopefully good enough for proof.

The famous Great Black Hawk, perched about 15 feet above the sidewalk.

What a cool experience. Nobody knows how long the Great Black Hawk will stick around. Will Maine’s frigid winter weather be too much for this bird? If it decides to move on, where will it show up next? So much mystery still surrounds it.

If you want to see uncommon birds like the Great Black Hawk, you can sign up for rare bird alerts on eBird-- either for the whole ABA range, or just for a particular county, state or province. You'll need a free eBird account, easy to create if you don't have one already. Then eBird will email you daily or hourly (your choice) about any reported rarities in the area(s) you select.  Although I’d never chased a rarity before, I had such fun seeing this one I set myself a goal to see two more rarities this year. Wish me luck!

By the way, I finished my antibiotics a few days after seeing the Great Black Hawk, and am back to 100 percent.