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

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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

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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.

 

 

Avian generations in the making – part 1: courtship

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The tragedies being faced in the Caribbean islands after hurricanes Maria, Jose and Irma are horrible and other than donate cash to help alleviate the needs, I’m not in a position to offer more assistance. I’m grateful for all those who can and hope government assistance will be forthcoming to help all the people in those nations recover.
The effects of the hurricanes also will be noticeable for the wildlife. Many of those living on land will drown or die of hunger; some birds may be a little luckier – able to shelter against the winds if they are native to a place or able to change their migratory pattern (e.g., delay arrival on wintering grounds) for a time. But when the effects of the storms are immense with lots of habitat destruction, the birds, too, will lack places to shelter and not have sufficient food supplies to survive.

It’s thought that some birds endemic to the islands may be severely endangered as a species. On 22 September, birders were happy to hear that eight Barbuda warblers (Setophaga subita) had been spotted on that island; not a lot but they may help ensure this tiny bird doesn’t become extinct.  At the time of writing this blog, the fate of some other bird species was still unknown. I hope that all the Caribbean bird species survive and will be thinking of them as I share this series with you on how birds take measures to ensure future generations. (It might seem odd to write this series now, but some birds are still feeding their young here.)

So, the process begins with courtship. Some birds mate for life, or at least form long-term (multiple-year) bonded relationships. They include bald eagles, black vultures, blue jays, Canada geese, white-breasted nuthatches, brown-headed nuthatches, Northern cardinals, Carolina chickadees, American crows, pileated woodpeckers and my favorite raptor shown above, the osprey (Pandion haliaetus).

Those who form ongoing bonds may have a courtship period that consists of the male bringing the female some food to indicate it’s time to get ready for nest-building. This was the case for these lovely Northern cardinals (Cardinalis cardinalis).

The American crow (Corvus brachyrhynchos) has a similar behavior; in my yard, I sometimes throw out bits of apple or bread for them in the spring as these seem to be considered real treats. The female will sit on a branch overhead calling until the male brings her some – and sometimes almost shoves it down her throat!

The Northern mockingbird (Mimus polyglottos) males will sing their repertoire in the spring to entice female mates – often they perch on the top of trees and fly up and down with spread wings in a beautiful display while singing.

        

   

The yellow-billed cuckoo (Coccyzus americanus) seeks new mates each year but has an interesting courtship behavior described by All About Birds: “A receptive female perches with its head up, pumping its tail slowly up and down…Just prior to mating, the male Yellow-Billed Cuckoo snaps off a short twig that he presents to the female as he perches on her back and leans over her shoulder. Both birds then grasp the twig as they copulate.”

 

     

 

The downy woodpecker (Picoides pubescens) females and males may both flutter between trees with slow wingbeats. Two females may also compete for the attention of a single male, a behavior I observed this past spring and which surprised me.

 

     

The male brown-headed cowbird (Molothrus ater) will vocalize for the female while spreading his wings in a display.

The killdeer (Charadrius vociferus) has a somewhat prettier courtship dance, bending forward and spreading its tail feathers to show off the colorful underside.

  

Next year, I hope to see more of the birds courting as it gives me a happy feeling.

The next step for the birds is nest-building. We don’t have the bowerbirds in North Carolina, who build elaborate nests as part of their courtship. But the species we have do spend a good deal of time on their nests and I’ll share some of their efforts in the next part of the series. (But one or two blogs on another topic will come first.)

 

Credit map: By Kmusser (Own work, all data from Vector Map.) [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)%5D, via Wikimedia Commons

Who wants to eat?

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First, let me welcome those of you who have become new followers of my blog – nice to have you reading here and I hope you comment on what you like! I am way behind on my postings for the blog but will try to remedy that. There are photos almost ready for a series on bird courtship and child-rearing, as well as some other non-bird topics, but various issues have been keeping me from completing the texts. Now that I have had to take my preferred camera in for repairs, however, I have a bit more time to work on the blog and a recent brief trip to Topsail Island is providing some almost ready-made postings.

The south end of Topsail Island has been eroded greatly by the Atlantic storms, including effects from Hurricane Irma. Where normally the beach sloped up gently to beautiful dunes, these have now been sheared off vertically and the sea grasses and other vegetation before the dunes have been swept away.

 

 

That is of concern as the sea turtles nest there; hopefully, there will be sufficient places for their eggs next year. There were far fewer shells on the beach but at low tide the swath of empty sand was very wide.

 

Mixed groups of birds were resting there in between ocean fishing expeditions. There were a couple immature common terns (Sterna hirundo) who were begging for food incessantly, but the adults pretty much ignored them, preferring to preen or settle down for a rest.

Some of the begging was pretty vigorous, accompanied by feather ruffling and shaking but I didn’t see any parents go off for food.

The sandwich terns (Thalasseus sandvicensis) were also resting but individuals took off frequently for a fishing flight. These terns are easily identifiable by the yellow tips on their black bills and their Groucho Mark hair-dos, a boon for people like me who are challenged in recognizing which shorebird they have before them. Sometimes, you could imagine a conversation taking place between them.

Hi! I’m back from fishing!

Didn’t take long, did it?

See, I got a fish!

Wanna smell it?

Not to your liking, huh?

Walking in circles around me won’t make it any different

I think I’ll go feed a young one!

There were two immature sandwich terns who were very persistent in asking for a meal.

Come on, Ma, I’m hungry!

I am really really hungry!

Oh yum, lunch!

That’s right, put it right here!

Thank goodness you brought me something!

I’m STILL hungry!

Perhaps the adult sandwich terns were accommodating to their young as they have a lot of experience in raising them – the oldest one on record lived in North Carolina and reached the ripe old age (for a bird) of 24 years and 2 months! (However, the oldest common tern on record was 25 years, so perhaps the sandwich terns are just more caring?)

The birds were quite entertaining to watch and I have more photos to share from that trip. I will try to intersperse them between postings on avian child-rearing. Have a nice day!

A cuckoo causing confusion and consternation, delight and distress….

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In the spring this year, I and another birder had the uncommon pleasure of seeing yellow-billed cuckoos (Coccyzus americanus) courting at Mason Farm Biological Reserve. These birds often stay high in trees, hidden by leaves, so it is always a treat to see one of them out in the open. Seeing two together, as the male tenderly offered his lady love a gift, was an unexpected pleasure.

 

 

Also unexpected have been my more frequent sightings of cuckoos in my yard. Last year, I had caught a glimpse of one in a crepe myrtle tree; I thought it was a lucky fluke. This year, I began to see cuckoos in the large trees of my front yard more often, though frequently they were half hidden behind the leaves of the willow oak, red cedar and persimmon. I did hear their identifying calls so I knew when they were around but not in sight.

Then, this past Sunday afternoon as I sat on my front porch photographing birds and insects visiting my flower garden, I suddenly caught sight of a cuckoo flapping about on a makeshift trellis I had arranged around an oak stump where I hope Carolina jasmine and other climbing vines will create a pleasing area.

The spot is popular with chipmunks and Eastern gray squirrels (Sciurus carolinensis), as well as many smaller birds like Renee, one of the banded Carolina wrens (Thryothorus ludovicianus) living in my yard.

     

But to see a large cuckoo sprawled on the branches was unexpected and I feared that it had an injured wing after escaping from a hawk attack. I took a few quick photos. Then I approached to get a better look — the bird tried to flutter away but didn’t get far.

I ran inside to get a box and the phone number of a local wildlife rehabilitator. I left a message and managed to get the bird in the box, to which it protested vigorously. When I closed the top, it calmed down and then the rehabilitator returned my call stating that perhaps it was a fledgling – I said it looked like the wing was injured so she asked me to take a photo of it.

When she saw my point-and-shoot camera photo, she said it wasn’t clear whether it was a juvenile or not and asked me to photograph the beak. Young birds have a yellow or bright “lining” where the beak meets the face. This area is called the gape flange and in most birds, the color disappears as they age and the beak becomes firmer.

      

With a slightly better photo of the bird’s head and beak, the rehabilitator informed me that this was indeed a young bird. She also told me that the bird probably was feigning a wing injury to get the parents to come back more quickly with food! On her recommendation, I put the bird back on a stump by the makeshift lattice.

I knew about killdeer adults pretending to have a broken wing and dragging it on the ground to lead predators away from a nesting area. The yellow-billed cuckoo adults will also do this distraction display.

But I had not heard of fledglings engaging in this ruse. The rehabilitator said she had known of crow fledglings that kept this up a couple days, although she didn’t realize cuckoos would do this as she doesn’t get many calls about this species. But, she commented, “birds aren’t stupid; a free meal is a free meal.”

I kept checking on the bird and it stayed on the stump quite a while. Then it hopped down into the leaf litter and made its way over to some large rocks under a cedar tree with low-hanging branches. First, the cuckoo just hung out on the rock. And all this time, it kept that wing stretched out.

Then the bird lunged upward to get onto the branch. At this point, I seriously wondered whether it wasn’t injured after all, perhaps having fallen out of the nest and hurting its wing when it landed. It got a purchase on the limb and continued to keep its wing out. Then it fell off the branch.

       

After a short rest on the rock, the fledgling jumped up on to the branch again and stayed there. I went inside and returned periodically to check on him/her. About 3.5 hours from time I first saw him/her, the bird was still resting on the branch with the wing out. S/he was no longer wary when I came to look but viewed me calmly.

About 30 minutes later, I went back outside for another check and found the bird on the branch, but now with its wings both folded in towards its body. I was really glad that it appeared to be ok and hoped the parents would come for it. I had heard them calling earlier in the afternoon but never saw them approach the offspring, though this may have happened when I went inside for brief periods. And when I finally looked at the first photos I had shot in quick succession, I saw a couple where the bird had drawn in both wings to hop about, only to stretch out its wing later again.

 

When it was almost time for me to leave for a theater engagement with a friend, I went back out to check one more time and discovered my cuckoo friend was gone. I examined the cedar tree to see if it was further up, as well as the trees and ground all around, and could find no sign of him/her. I hoped that s/he finally decided to give up the display and just flew to a better place. I did check the area the next two days but did not see the bird again.

Then, this morning, a distressing finding started off my day. When I went outside, a neighbor boy was staring at the ground in front of my street-side willow oak. When I got there, the cuckoo lay dead at the street edge. He said he had seen the bird yesterday sitting on the road “with a broken wing”. I wish I had seen it – I don’t know if the bird had really been injured after all, was feigning an injury and then fell prey to a neighbor’s cat (which is what I think happened as its underside looked like it might have been in a cat’s mouth), or if something else occurred. In any event, it was such a sad discovery.

I buried the cuckoo while regretting how short its life was. I’m glad I don’t let my cats roam about anymore and I wish neighbors would also keep their felines inside, even though I know that birds might fall prey to a hawk or die because of a disease. But I wish I’d been able to help this beautiful young bird. My emotions tell me the cuckoos won’t return but my mind says they won’t avoid the yard because they lost an offspring. Time will tell.