Costa Rican rambles 7B – Cerro Buena Vista and a night prowl

 

After seeing the beautiful green and blue emerald swift lizard, our attention went back to birds and we rewarded with sightings of a few gorgeous little yellow birds – a yellow-winged vireo (Vireo carmioli) and yellowish flycatcher (Empidonax flavescens).

Since I photograph insects to contribute to BugGuide in the USA, I was watching for them in Costa Rica, too. Insect galls on plant stems and leaves were in evidence and a blue damselfly (Argia pulla) posed for a moment.

A yellow weevil was a fascinating find – those blunt-nosed small insects make me think of Pinodchio.

Then – to the delight of everyone in our party – we had the good fortune to see a resplendent quetzal (Pharomachrus mocinno) fly across our path. We had caught sight of a couple flying high over the Lodge before setting off for our hike, but this bird actually perched not too far away, not staying very long at all but giving me a minute to step around a fellow birder and get a couple shots.

A hairy woodpecker (Leuconotopicus villosus), a more familiar bird for us, looked down on us from high above and a flame-throated warbler (Oreothlypis gutturalis) brought another spot of color to our upward trek.

 

When we started down to make it back in time for lunch, we had time to examine the surrounding flowers and then were lucky to see yet another emerald swift lizard, also kown as the green spiny lizard (Sceloporus malachiticus).

After a meal, it was a treat to see a collared redstart (Myioborus torquatus).

 

 

   

 

A black-thighed grosbeak (Pheucticus tibialis) gave us another yellow-hued sighting before our attention turned to birds with more subdued coloring – an ochraceous wren (Troglodytes ochraceus) which made me think of hobbits in woods for some reason, some ruddy treerunners (Margarornis rubiginosus) and a spangle-cheeked tanager (Tangara dowii).

        

A black-faced solitaire (Myadestes melanops) graced us with its presence before we took an afternoon break. Some of our fellow birders went to rest, but Janet invited me to her cabin where we had the rare pleasure of seeing a lesser violetear hummingbird (Colibri cyanotus) sitting on her nest! When she flew off after a while to get some sustenance, we noted that she had not yet laid any eggs.

 

 

Then, as I scanned the surrounding trees from Janet’s balcony, I discovered another nest, occupied by the young of a gray-tailed hummingbird (Lampornis cinereicauda). It was not easy to see but peering through the leaves, I managed to get a shot of the hummer stuffing some food down an offspring’s throat.

   

Janet’s balcony was a wonderful birding spot – the next visitor was a gorgeous red-headed barbet (Eubucco bourcierii). A flame-colored tanager (Piranga bidentata) was yet another brilliantly hued avian visitor.

Walking along the nearby roads, I saw the horses (Equus ferus caballus) used for tourists’ horse-back riding galloping along – beautiful, well-fed animals to be sure.

  

We soon left on our next excursion to the Páramo zone (montane shrub- and grassland mountaintop environment), where we scaled the Cerro Buena Vista (“Good View Mountain”) by van. This region contains the highest point of the Pan American Highway in Central America (3492 meters or 11456.69 feet in elevation). The peak harbors telecommunications equipment and is noteworthy for the many bird species endemic to this area.

   

The one for which we were especially looking was the volcano junco (Junco vulcani), a great bird that was not shy at all and posed for us in numerous positions and at great length.

After leaving the mountaintop, we descended to the rainforest and there spotted a black guan (Chamaepetes unicolor).

 

Our day ended with a night prowl after dinner, looking for the dusky nightjar (Antrostomus saturatus). And we were lucky enough to have one fly right in when it heard the playback of a compatriot on our birding guide’s sound system!

 

 

 

Well satisfied, I retired to a good night’s sleep after catching a rather large cranefly-type insect, which I let go outside. I wanted to be prepared for our next day’s adventures with the wildlife beauties of Costa Rica.

Avian generations in the making – part 3A: raising and feeding babies

So here in North America, it’s approaching winter and it may seem a bit weird to have another blog at this time on birds raising their young. But I wanted to complete the series even though it has been delayed because of my volunteer activities and commitments the past month. Also, it is now late spring in the Southern hemisphere so for some people this is seasonal and there are other birds around them that are getting ready for babies, though different species than these American robins (Turdus migratorius). Because this part kept growing longer as I worked on it, I’ve divided it into two parts – this one on raising the babies until fledging and the next one on fledging and post-fledgling care. I hope all of you who read this will enjoy it no matter where you live.

It’s fascinating to me to watch the birds during their reproductive cycle; I always learn something new. Once parent birds have completed a nest to their liking, the female lays her eggs and proceeds to brood them, with some species sitting on the eggs almost full time right away and others taking breaks.

           

Carolina wren (Thryothorus ludovicianus)              Eastern bluebird (Sialia sialis)

An acquaintance recently told me about a friend of hers who commented that she had seen a very pregnant goose that was so fat, she was waddling. The acquaintance proceeded to give an avian reproduction lesson to her friend – a woman in her 80s – who apparently did not know all birds lay eggs! Even after babies hatch, the Canada goose (Branta canadensis) may still look well-fed!

Some bird species have young who are “precocial”, that is, they are covered with downy feathers and have open eyes when they hatch and are soon able to feed themselves. These species include turkeys and ducks, like these mallards (Anas platyrhynchos), and the young often leave the nest soon after birth (which makes them “nidifugous” – good Scrabble word!). The newborns may look fuzzy but it’s not long before they start to take after their parents’ looks.

Other birds, such as songbirds, are altricial (as are human beings) – they are naked and helpless at birth and require considerable care before they can walk, fly and feed themselves. If you have some in a nest that is easily observable (and you can take photos when parents are not there so you don’t distress them), it’s interesting to see how the babies develop.

               

Carolina chickadees (Poecile carolinensis) on 18 and 22 April           

Brown-headed nuthatches (Sitta pusilla) on 13, 25 and 29 April

 

 

Eastern bluebirds (below)

     

As the mother incubates the eggs, her mate will often feed her so she doesn’t have to leave the nest. This young osprey (Pandion haliaetus) was assiduous in bringing his female life companion fish. Then as the babies hatch, in many species both the male and female parents get busy bringing the young frequent meals.  It’s estimated that Carolina chickadees, for example, will bring over 5000 insects to their brood before fledging!

Northern mockingbird (Mimus polyglottos)

     

House finch (Haemorhous mexicanus)  and Red-headed woodpecker                (Melanerpes erythrocephalus)

              

Orchard oriole (Icterus spurius)                  Blue grosbeak (Passerina caerulea

  

Eastern phoebe (Sayornis phoebe)

In some species, the previous year’s young will help their parents with the new brood. Brown-headed nuthatches and American crows are examples of this. A pair of Canada geese that I observed this past spring seemed to have a domestic goose helping them out.

The parents have other chores, too. They must keep the babies safe from predators – Both American crows (Corvus brachyrhynchos) and common grackles (Quiscalus quiscula) will be chased away by songbirds, for example, because these birds will raid nests to eat eggs and babies. But the grackles must also protect their own young against the crows, pursuing them non-stop to drive them away.

 

For other birds, protecting the young can be more difficult. This mother wood duck (Aix sponsa) was raising her brood in a pond that was home to at least three large snapping turtles (Chelydra serpentina). Ultimately, another birder and I thought she only had two ducklings survive.   

Keeping the nest reasonably clean is another chore. The babies make this task a little easier than you might think because they defecate into a mucous membrane that forms a sac. When you watch a nest box, especially when it gets closer to fledging time, you can periodically see the parents flying out of the box with a white blob in their mouth, which turns out to be a fecal sac. They either discard it elsewhere or sometimes eat it for some nutritional benefit.

        

Brown-headed nuthatches

This year, I was surprised to have caught a female blue grosbeak during the cleaning – it appeared that she was actually pulling the fecal sac from the baby! Later, I read that some species stimulate defecation by prodding the babies’ cloaca so they can get on with the chore. I also caught a photo in which a baby bluebird had just presented its rear end to the parent for removal of a sac. I could imagine that some human parents might think a fecal sac would be a cool avian adaptation for their babies to have – no more dirty diapers and expense for diapers either! (An idea for an SF short story?)

     

 

After all their efforts, the parents are usually ready for those babies to fledge – the subject of the upcoming last blog in the series.

 

 

* Not all the photos in this blog are of great quality, I know, but my intention was first to show behaviors and secondarily to have some nice shots in the blog.

 

 

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.)