Avian generations in the making – part 2B: nesting in nature

My last blog looked at birds’ nests in man-made structures and there are plenty of birds who take the opportunity to use such sites. Most birds, however, make their homes out in nature – in shrubs, trees and on the ground. This is a bit of a long blog but I want to share views of different species at work.

There are different types of nests; a few types that we see in North Carolina include:

  • Cavity nests – holes in trees, made by the parents themselves or adopted as a home when birds like the cavities made by others
  • Simple scrapes – these are shallow depressions scratched out on the ground and they may be lined with materials or left to look like the rest of the surrounding ground
  • Cup-shaped nests – these structures are like small bowls and may be lined with materials like those used in nest box nests. They can be made of varied materials – swallows use mud while American robins and other birds use plant materials.
  • Platform nests – these nests are usually quite large and comprise large twigs and small branches
  • Plate nests are a bit similar to platform nests but much smaller and less organized; they may consist simply of a few twigs arranged in a shallow bundle
  • Pendant nests hang from branches.

When birds look for a cavity site, they may seek out a new spot on a tree trunk or investigate already existing cavities. These Eastern bluebirds (Sialia sialis) at Sandy Creek Park were examining one particular hole with interest, but a downy woodpecker was interested as well so there was some rivalry. The female bluebird chose to just sit on a nearby branch while her mate looked at the hole numerous times trying to make a decision.

    

Red-headed woodpeckers (Melanerpes erythrocephalus) excavate larger cavities in tree trunks to raise their broods. They may visit various trees before deciding on a spot.

      

Pileated woodpeckers (Hylatomus pileatus) may use the same holes year after year. They make holes for resting as well as for nesting and often include a “back door” so they can make a quick escape if a snake shows up.

          

Brown-headed nuthatches (Sitta pusilla), like this one at Jordan Lake, can be very industrious in excavating their nest cavities. You can watch them pecking away at the wood of a tree trunk or branch, scattering wood shavings and removing bigger bits of softened wood in their beaks to achieve a hole of the right depth for their babies. (See a short video of one at work here.)

   

I also saw nuthatches making nests on the edges of a farm and near the NC Botanical Garden. The pair working on a nest at the Garden were doing this with a great horned owl on a branch overhead, as well as a red-tailed hawk and crows who were raising a racket. Their presence didn’t bother the little birds; these nuthatches also appeared to have help from a previous year’s youngster willing to help the parents raise the new siblings.

 

 

    

Carolina chickadees (Poecile carolinensis) also dig out small holes in trees and snags.

      

Killdeer (Charadrius vociferous) use scrape nests which may look exactly like the surrounding area; their eggs then blend in really well with the environment and can be difficult to see.

When I first saw this nest suspended from a tree near a bridge, I had no idea which bird had built it. A birding friend had fortunately seen the parent bird fly to the nest – it belonged to a Northern parula like the one shown below (Setophaga americana).

    

I was lucky to see a female orchard oriole (Icterus spurius) collecting nice soft lining materials for its nest this past spring.

         

A red-winged blackbird (Agelaius phoeniceus) was doing the same with cattails – an obviously appropriate source for bird bedding!

       

Mourning doves (Zenaida macroura) and Northern mockingbirds (Mimus polyglottos) make fairly shallow, twiggy nests (“plate nests”). It makes you wonder if eggs ever roll out of them through cracks in the loose, low walls.

   

Many birds make cup nests and spend a good amount of time collecting the materials to produce them. Here you see American robins (Turdus migratorius) gathering grasses – they tend to fill their mouths as much as possible before flying off to the nest-in-the making.

      

Red-eyed vireos (Vireo olivaceus) will also attempt to get several pieces of bark into their beaks before flying back to the home site. The photos here are dark as the bird was deep in shrubs where little light was penetrating.

        

Blue grosbeaks (Passerina caerulea) weave what looks like a cross between a pendant nest and a cup nest; they also add man-made materials such as rags, cellophane, newspaper and bits of plastic.

    

Great blue herons and ospreys are builders of platform nests.The great blue herons (Ardea herodias) carry large twigs and branches to furnish a nest. At Sandy Creek Park they have been using the same tree-top platforms for several years now.

     

Last year, I saw this osprey pair (Pandion haliaetus) build their first nest from scratch; they weren’t enthusiastic about me being in the vicinity and would perch or fly overhead to give me “the evil eye” – sometimes calling to one another to sound the alert that they had spotted me down below.

 

 

This year, they were busy refurbishing the nest – these birds with longer-term mates may use the same nest year after year. Again, they would stop their work to stare me down.

 

The Acadian flycatcher (Empidonax virescens) makes a cup nest that is well-hidden among the leaves of the tree spot it chooses. A friend saw the pair constructing this nest and it was done by the time I visited. It seemed quite a tight fit for mom to sit in while brooding her eggs.

The bird whom I enjoy seeing most during nest construction is the blue-gray gnatcatcher (Polioptila caerulea). These little birds are very active and often don’t sit still for long as they feed in shrubs and trees. When they are busy making a new home though, they take their time to do a good job. First, they locate good locations for the materials they use – leaves, spider web to hold the leaves together and pieces of lichen to cover the outside walls.

      

They affix the lichen carefully to make a really beautiful, compact and elegant little cup. The female then sits in it and moves her body to ensure it gets the right shape and dimensions for her upcoming brooding.

     

The male and female both work hard on the nests and this year I got to see three pairs at work. In two cases, it was lucky I saw them flying to and fro because their nests blended in really well with the tree.

Unlike the cavity and platform nesters, the cup and pendant nesters usually need to build a new nest each year. At the end of the summer, for example, the blue-gray gnatcatcher nest had already deteriorated considerably with the rain and wind, even though it was a fairly calm and dry season.

 

Once the nest is complete, the avian parents brood and feed their babies before fledging and this will be the third part of this series. For now, I leave you with the male and female ospreys as they watch the birdwatcher….

  

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.

 

 

Can you go home again? Apparently so!

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This year, I had the good fortune to see both brown-headed nuthatches (Sitta pusilla) and Eastern bluebirds (Sialia sialis) raise broods in some of my nest boxes. I saw the babies fledge, which was truly an enjoyable event.

 

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For some time, the parents continued feeding their babies after they left home, but eventually they got to the point that they could catch or find their own food. As summer progressed, the parents and children both visited my feeders and it was gratifying to see the families thrive. Then during September and October, I saw a behavior that I don’t remember from years past.

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The nuthatches started to return to their nest box almost daily. They didn’t check out nearby boxes but went to their original home and today they are still visiting there, sitting on top, fluttering around it and looking inside.

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Their frequent visits seem to have intrigued a local tufted titmouse (Baeolophus bicolor) who decided to take a look in their box, too,but that was only a one-time visit as far as I could see.

It’s not only the parents doing this, but also one or more of their offspring. So how true is the saying “you can never go home again” (origin a novel by Thomas Wolfe)? It originally meant that you can’t recapture exactly how things were in your youth because changes take place in situations and places. But people do often journey back to the places where they grew up and apparently birds do, too! Maybe they are wondering if their nest box is still the same good place for a home.

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The bluebirds began doing the same with their home nest box as well. They take turns flying from nearby branches to cling to the box and investigate the now empty dwelling. While the nuthatches just lean and peer inside, the bluebirds eventually go inside for a bit.

 

 

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Oddly, there seems to be some contention involved. For example, when this pair was investigating, they had a little tiff for some reason.

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I can only guess that the birds are checking out the nest boxes in anticipation of next year’s nesting season. The nuthatches and bluebirds will begin breeding again around March, although nuthatches might already begin building a new nest as early as December. It will also be interesting to see if they end up roosting in the boxes during the colder winter nights.

brown-headed-nuthatch-i77a4527-maria-de-bruyn-resWatching the nuthatches and bluebirds nest, fledge and feed is an enjoyable pastime and I’m looking forward to seeing them repeat the process next year. In the meantime, perhaps I’ll continue seeing them around the nest boxes this winter – as Pliny the Elder said, “Home is where the heart is” and something is sure attracting them back! (And yes, I know, that is a bit of anthropomorphizing.)

Leaping into the wide – and sometimes wet – world!

Eastern bluebird IMG_2991© Maria de Bruyn resEarlier this past week, I calculated that the Eastern bluebird (Sialia sialis) babies in my front-yard nest box were close to fledging. I knew approximately when mom had finished laying her eggs (four in total), so that I could guess when they reached normal fledging age (16-18 days after hatching). When I looked at the nest on 10 June, I saw that there were only three babies; I have no clue what happened to egg No. 4.  But the three survivors were progressing well as mom and dad made frequent forays to gather caterpillars and insects for them.

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Occasionally, the male and also the female bluebird, identifiable by her subtler coloring and her brood patch, would visit the suet and meal worm feeders for a fast food repast for themselves. It was hard work keeping their growing offspring fed!

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They also had to let one of their older offspring from a previous brood know that they were no longer going to feed him, even when he begged.

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As fledging time neared, mom and dad had to contend with other birds coming near the box. Dad was especially angry with a young starling (Sturnus vulgaris) who wanted to settle on top of the box. Starlings have been known to eat young birds and papa bluebird was obviously taking no chances! (I just caught the action out of the corner of my eye so the photos aren’t great but do give an idea of the argument!). The parents also chased away squirrels from the tree in front of the box, which alerted me to the fact that fledging was probably imminent since the parents become especially protective at this time. I started using a smaller camera with a very long zoom (but somewhat lesser photo quality) as they weren’t excited by me being too close either.

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On Wednesday, I checked the box before going out for the morning and there were still three babies there. When I came home a few hours later, mama and papa were sitting on branches, with or without food, calling to their little ones to come on out. They would also fly to the box for a quick look inside.

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Mama also repeated behavior I had seen last year – flying to the box, standing on top and then hovering in front of the hole as a form of encouragement.  When she and dad left, I approached to take a look and discovered bluebird baby No. 1 had already flown away. This meant that the parents had to watch the first baby out in the trees somewhere, as well as their two lagging offspring in the box.

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Eastern bluebird I77A8592© Maria de BruynAt one point, mother bluebird seemed a bit fed up – she flew over to the box (without food) and finally entered, staying inside for a good 60-90 seconds at least. I imagined her giving the babies a lecture about how they had to be courageous and willing to jump.

Her admonishments seemed to have had an effect; the babies began calling loudly from inside their birth home. Finally, after about 30 minutes, one poked its head out to take a look at the big wide world. Mom and dad seemed glad, waiting together in the tree to see how long it would take baby No. 2 to join them.

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The baby looked around a lot, also staring at me; s/he went back inside and then looked out a few more times, finally taking the great leap into the outside world. Baby 2 was a very strong flier – not even alighting in the tree in front of the box but circling around to land high in a juniper and then in a tall oak tree behind the box.

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Sibling No. 3 took a little while longer and mama bluebird again went to the box to give encouragement. The baby then spent a little more time observing the new environment and also made a strong flight out.

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It rained that night and I hoped that the bluebird babies were ok; between the thunderstorms and a neighbor’s cat who comes to hunt birds in my yard, their environment seemed precarious for their first days of life. In the afternoon, I was happy to see papa bluebird feeding one of the three babies at the top of an oak tree. Mama was also flying around up there, so I assumed they were all hanging out in the high branches.

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Thursday night, it rained heavily again for many hours; Friday was an easier day and night. I haven’t seen the fledglings again yet but have seen their parents coming for suet and meal worms and flying up to the oak tree, so I assume at least a couple are there. I look forward to seeing their speckled selves at the feeders along with their parents – and will be curious to see if their parents go for a third brood this year.

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Living above a restaurant

house finch nest 1 IMG_4358© Maria de Bruyn resAt one point in Amsterdam, I lived in a room with a shared kitchen and toilet above a butcher shop. It was a cramped space but I made some nice friends there. Eventually, I painted the hallway with flowers and snails to bring a bit of nature inside. Today, on my way to a prompt writing session, I saw that some birds also choose to live above commercial establishments, including those who established homes above one of my favorite restaurants, El Tigre.

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There were three nests (at least – I didn’t look around to the other wall), with house finches (Haemorhous mexicanus) on either side of a European starling (Sturnus vulgaris) home in the middle. Nest 1 had a female bird visiting while a couple stayed inside.

 

The other finch nest was attended by both mother and father.

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European starling IMG_4390© Maria de Bruyn resThe nest with starlings had rather large babies in it. At one point, an adult bird flew in with a worm or insect but then took off before feeding anyone – perhaps alarmed when it saw me watching the nest. The babies didn’t say much, in contrast to the somewhat older baby starlings in my yard who make quite a racket asking to be fed.

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I wasn’t the only observer, however; a couple house sparrows (Passer domesticus) were also observing the comings and goings to and from the nests.

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I had a busy day and didn’t think I’d get to do much nature observation – but then those adaptable birds showed me that even in an urban environment, I can grab a few moments to see what other species are doing on a lovely spring day!