Vulture Venture

I have been short on new blog material lately.  The only interesting new finds have been swarms of midges coming out on unseasonably warm January days, a mating behavior usually scheduled for late March and April.  The only way I could catch them is by hand which squashes them too much to ID the species.

One constant finding at Bull Mills this December was the black vultures sitting on the corral rails behind our barn.  This is the 15th annual brood raised in the Vulture Obstetrical Ward (aka our 120 year old barely standing barn). Last year we didn't see any eggs or chicks and had given up on them when I suddenly saw the juvenile above, filmed in this video as it prepared to fledge.  

 

Click to enlarge

There are several stalls which I can't open due to settling and the groundhog holes are now vulture tunnels.  Back in 2013 we wrote this blog about a vulture family raised in a hollow tree which I filmed through a two inch crack.  They hiss a warning, "I am bad and will vomit on you" as seen in this video.  How the chicks managed to get up eight feet to the open top of the trunk to fledge is beyond me. 

We get a better view of them in the barn each year as seen in the Now Eat Your Carrion blog.  They hiss the first few times I open the door but soon learn to totally ignore me.  The parents would initially flush out the window but later just looked bored.

 

Last year's fledgling wasn't quite ready to take flight when I found it so I came back a few days later for its maiden voyage.  They are still hanging around the barn on the corral rail on warm days, now without their juvenile downy feathers.

 

MDC Nature Calling had a great story on vultures, everything you ever wanted to know.  I found this about killing livestock interesting.

"It can be difficult to tell if a black vulture actually killed the animal it is feeding on or found it already dead. Farm animals, especially newborns, die from many causes. But black vultures sometimes do kill newborn calves and lambs. They are attracted to the afterbirth and may try to eat a newborn that is not yet able to stand and move away. Because black vultures tend to feed in groups, it can be hard for cows or ewes to scare them off, especially if they are first-time mothers."

 Here is the whole vulture story from MDC.  

 

More pictures of our annual vulture adventures are seen in this Flickr album.

Snakes Alive

Lone Star Tick- Wikimedia

Following an extremely mild winter, the early arrival of animals and plants usually associated with mid-April shouldn't be surprising.  Common sense would suggest that the ticks that crawled over us all through this year's winter months would create a bumper crop in the spring.  Mike Penprase wrote about this in Thursday's News-Leader article How did area critters survive winter?.   He quotes entomologist Rob Lawrence, the Missouri Department of Conservation’s insect expert.

“The whole issue of insect and tick survival in the winter and predicting it is much more complex than we might think. That’s because a very cold winter doesn’t always guarantee that insect populations will be low once warm weather begins," he said.  "Cold weather causes insects to go dormant, and bugs that burrow into the soil or have other protection tend to survive. Continuous cold, in some cases, actually is better for insect survival. Insects that leave dormancy and become active during warm weather often don’t find food needed to survive."

Driving the lane along our glade at Bull Creek, I came across a 30" timber rattlesnake which we had apparently driven over the day before.  It had been taking advantage of the warm weather to head out hunting.  Basking in the sun would be common but I was surprised that it had roamed this early from the south facing rocky shelf rocks that its family normally calls home.

Find the rattle- click to enlarge

Timber rattlesnakes occur in small numbers in the Ozarks, but our land seems unusually blessed with them.  The terrain (wooded slopes with lots of shelf rock overhangs) and aspect (the southerly direction the rocky slopes face) is a description you might find the the real estate section of Timberrattler.com.  While they are unwelcome around our house and garage, it is always exciting to get to see them in the wild along Bull Creek (see picture).  They are a beneficial species and an important strand in the web of life.

Another sign of early spring was the appearance of a black vulture on the corral fence of our old deserted barn.  They had nested in a stall there last year, entering through some missing boards in the wall.  We had the privilege of watching their chicks grow up into fine adults (picture).

 Allaboutbirds says this about black vulture nesting habits:

"Instead of building a nest, the Black Vulture lays its eggs on the bare ground of the chosen nest site. Parents incubate the young equally. The Black Vulture lays its eggs in isolated locations with little human disturbance. They find a dark recess in a cave, abandoned building, thicket, pile of rocks, or in a hollow log or tree. A pair of Black Vultures may assure themselves of the site’s isolation by perching nearby for a period of weeks before egg-laying."

Vulture chicks now grown

The fact that the vulture was undisturbed as we stopped within 10 feet to look at it raised the hope that it is considering using the same nursery this year.  We are going to avoid the barn for several weeks to avoid scaring off these potential renters.  Vultures are good citizens of Bull Creek,  serving our community in a mortuary capacity by disposing of the exposed remains of mammals.

Early or not, ticks or no, you gotta love spring.

Vulture Eggs

Black Vulture

I took several friends out to the barn to see the barn swallow nests and found a surprise.  As we walked toward the back, something large and black flew out of a side wall and landed on a wooden fence rail.  It took us several seconds to register as we didn't expect to see a black vulture in a barn.

A black vulture finding prey in a barn is unlikely in a species that hunts mainly by sight.  We opened the door carefully and there on the thick straw on the floor lay two large eggs.  We took several pictures and left it alone.  The next day we confirmed that she was back on the nest.

Click to Enlarge

In a recent blog we discussed the differences between turkey vultures and black vultures.  As they hunt by sight instead of smell like turkey vultures, they generally avoid heavily wooded areas.  We occasionally see black vultures soaring but they are much less common that turkey vultures in the valley.

Black Vultures, Coragyps atratus, usually lay 1-3 eggs in cracks and caves along cliffs or in a stump or dense vegetation.  There is no nest built, and the parents take turns incubating the eggs over 37-48 days.   Once the eggs hatch, the young are fed by the parent's regurgitation.  You would think this would encourage them to leave early but they don't take off for around 80 days.

Vulture Society

Unlike turkey vultures, the black's chicks are yellow-tan, with feathers extending over their head.  They will eventually lose the head feathers, going bald like some humans.  This helps keep their head clean when they immerse themselves in their food (no further comment required).

Vultures defense against intruders is to vomit on them "with power and speed."  Having retired from gastroenterology several years ago, I do not intend to intrude on them up close and personal.  However we will cautiously take pictures at intervals.

Now Eat Your Carrion

When the chick is young the parents pick up small pieces of food and feed them to the chick, but as it gets older, it picks up these regurgitated food items on its own. Chicks remain in the nest for two to three months and continue to depend on their parents for a period of time after fledging, until they learn how to find and compete for food on their own. By the time they are ready to fledge, at three to six months old, the chicks are nearly the same size as their parents and are fully feathered, but their coloration is different. - See more at: http://animals.sandiegozoo.org/animals/vulture#sthash.tegIA6vt.dpuf

"Now eat your carrion like a good little vulture chick!"

I recently had the opportunity to watch our black vulture parent introduce the chicks to solid food.  Initially chicks are fed by the parent regurgitating digested food into their open mouths.  As they get older, the parent picks up small pieces of food and feeds them to the chick, before it learns how to pick up these regurgitated food items on its own.

I opened the stall door where the 5 day old chicks and parents are living.  The adults are accustomed to my visits and ignored me, while the chicks made a soft hiss when they felt threatened.  This time there were several strips of meat on the floor.  While I got my camera out I watched one chick repeatedly pick up a piece, trying to throw its head back to get it into its mouth.  It quit in frustration just as I was ready to film it.

"Tried it, didn't like it."

I have read that vultures will occasionally glean ticks.  This parent was gleaning a lot more than ticks.  Each time I opened the door to the stall, the parent stepped back and then started picking at things in the dirt, sometimes dropping an object, other times making a movement to swallow it.  Once I could see it was a small bug or beetle.  As you will see in this video, the parent is walking around the stall, gleaning insects from the stall floor, carefully selecting what to eat and what to discard.

These chicks will remain in the nest for two to three months, continuing to depend on their parents for regurgitated food until they fledge.  Even after taking flights across the field, they will depend on parental feeding for a while although they are nearly the size of the parents. *

Eat what?

A vulture's diet is enough to gag a maggot, so how do they survive eating carrion rotting in the sun for several days?  They can tolerate large loads of bacteria growing on carrion due to their unique mix of Clostridia and Fusobacteria gut bacteria.  Also, their gastric juice is far more acid than most birds, a remarkable pH of 1 to 2.

Like mothers everywhere, the adult eventually ate the piece of carrion to clean the plate.

In some countries in Southeast Asia, vultures are dying in large numbers.  The cattle that are revered are also treated with drugs like diclofenac.  When they die natural deaths rather than being butchered by humans  they are eaten by vultures which frequently develop kidney failure from the drugs.

*Sandiegozoo.org
There is a good overview of black and turkey vultures at Trekohio.com.

When the chick is young the parents pick up small pieces of food and feed them to the chick, but as it gets older, it picks up these regurgitated food items on its own. Chicks remain in the nest for two to three months and continue to depend on their parents for a period of time after fledging, until they learn how to find and compete for food on their own. By the time they are ready to fledge, at three to six months old, the chicks are nearly the same size as their parents and are fully feathered, but their coloration is different. - See more at: http://animals.sandiegozoo.org/animals/vulture#sthash.tegIA6vt.dpuf

Vultures In The Tree

The last three years we have been posting stories following the progress of black vultures which nest in a stall in our century old barn.  Perhaps "nest" is too strong a word as they simply lay their two eggs on the bare ground in thickets, rock piles or caves.  In this story, they chose a hollow tree.

Young Vulture- 2012

Last year we were cruising along pond trail when our friend spotted a pair of immature vultures sitting on a broken upright tree trunk.  As we slowly walked closer, they dropped down inside the hollow trunk with a deep "thump."  Over the next few weeks we watched as they shed the few remaining white down feathers from their necks and then they were gone.  The tree was only a thin rim of wood with several holes and I didn't expect it to last the winter.

Yesterday as I drove the pond trail, I stopped to check out the old tree.  The hollow trunk is a little shorter now, just over 6 feet tall, a thin barrel of wood with cracks in the sides.  I tapped it lightly with my knuckle and it resonated with a deep pitch.  Then I heard a soft low-pitched hiss, the distinctive sound of a vulture chick warning me to get away.

Vulture Tree Base

The current digital boom has provided many wonders, such as the pocket camera.  I found a small opening in the base of the tree made by wood slowly being digested into soil.  With my camera in movie mode, I lowered it blindly into the opening to record the sound.  Each light tap on the trunk brought forth another hiss.

Although I couldn't see the screen on my camera, I decided to try taking some pictures blindly.  Each flash of the camera brought on another warning hiss.  To my surprise I managed to get several decent portraits of the chicks.

 

"HISS- I'm big and I'm BAAD!"

In addition to capturing the sound with the video, I actually got some pictures inside their decaying tree house.  They will be there for several months, fed digested dead flesh by their parents until they are strong enough to go up through the hollow trunk to the top.  Meanwhile, you can get a glimpse of life in a tree trunk with this video.

Vulture Migration

After several rainy cold days the sun returned for two glorious fall days.  After several hours cutting firewood, I treated myself to a nap on the newly cut hay field along the edge of the valley.  I was looking up at the blue sky and the orange and red leaves above my head and feet, with an open horizon to the north and south.

I noticed a tiny speck appear in the north.  As it came overhead I could see the typical shape of a soaring turkey vulture, its wings held above in a flat "V" shape.  It was flying higher that I had ever seen and another speck followed, then another, all spaced out but headed in the same direction.  Eventually I counted 25 over 5 minutes, with never more than 5 scattered in the visible sky at a time.

After 15 minutes my dog came over to tell me it was time to get back to work, but as I started to get up another speck came in sight.  I checked the time and start counting again, ending with 53 when the parade ended 10 minutes later.  Again, not a single wing flap the full time, and the vultures were always widely separated.  There were never more than 5 birds visible in the whole open sky at one time.

Thermal updrafts allow turkey vultures much longer flights while soaring with their wings steady.  The vultures migrate in the daytime and avoid rainy or cloudy days which don't have the updrafts that allow them to glide without flapping their wings.  In the full time that I was watching them I never saw a single wing beat, just their steady glide and distinctive teeter from side to side as described in Bird Note.

Research on turkey vulture migration included a bird fitted with a heart-rate logger during 124 hours of flight during 38 contiguous days.  That showed only a small increase in mean heart rate as distance traveled per day increased, which suggests that, unlike flapping, soaring flight does not lead to greatly increased metabolic costs.

I didn't get any pictures as I could never get more that two birds in a frame of my telephoto.  It was just one of those "you had to be there" days.

Egg Season

Black Vulture on eggs

In the spring, a young bird's fancy turns to thoughts of... making babies!  Evidence of this trend abounds along Bull Creek this week.

The most dramatic has been the return of the Black Vulture family.  I first saw them close up in March when I drove within six feet of a pair sitting on the corral fence.  They didn't budge when I stopped, suggesting that they were the ones that became acclimatized to us during their nesting last year in the old barn.

Black Vulture Babies- Day 1

We waited patiently for three weeks, afraid we might scare them away, then looked in the barn on April 1.  Our patience was rewarded by the sight of two large blotchy eggs.  We didn't see them again for a month as one of the parents remained on them full time.  Last year they would flush on our entry, further evidence that they had lost fear of us.

On May 1 the chicks first appeared, cute fuzzy little balls that are sure to elicit a response of "awhhh."  Unlike the bluebird and chickadee babies in bluebird boxes who lay still with their eyes shut for the first few days, vultures are born with their eyes open and their feet moving.   They still aren't a ball of energy yet, their main tricks are limited to turning their head and a little wiggling. 

At the other end of the field, we came across a turkey nest with eight eggs in a elderberry thicket.  We returned two days later to see if there was any activity and Barb crept up on the area to investigate.  (See turkey flush above)  It was like flushing a quail on steroids.  If you think that the flushed turkey was startled, you ought to try being the "flusher."

Turkey Nest

This time there were just 6 eggs in the nest.  Sadly, when we returned today, we could see from a distance that the nest area was trampled down and empty aside from a few small dark feathers.  The good news is that incessant gobbles ring throughout the Bull Creek valley, advertising the opportunities to love and mother again.

Fledging Time

It is fledging time on Bull Creek.  The century old barn is functioning as a pediatric ward full of barn swallows as well as the black vulture chicks.  There are at least 7 swallow nests glued to the beams, each brimming with chicks warming their engines for takeoff.  Every time we entered the barn in June there was a mass of zooming parents darting in and out and chirping hysterically.  By now they don't pay much attention, having become accustomed to our coming and going just like the vultures have.

Barn Swallows, Hirundo rustica, are a common sight around our land, swooping over our garden and patrolling up and down the creek, dining on a rich source of flying insects.  They dart gracefully at low levels, sometimes just skimming the water.  Their distinctive pointed V-shaped tails and flight pattern cannot be mistaken for any other bird.

These swallows have made a successful adaptation to the presence of humans, so much so that their nesting is almost exclusively limited to man-made structures.  Their numbers increased dramatically as we spread barns and farm structures across North America and they found the perfect place to next.

Baby seals??

Now that the chicks are close to taking off, they have become curious about our visits.  Peering over the nest, they don't make a sound.  Looking at them head on so you can't see their pointed beaks they almost look like baby seals.

Driving down pond trail with Mike Kromrey's parents, his mother, Sandy, spotted some "big birds."  Sneaking up on them with camera in hand, I got some good pictures of a pair of black vultures sitting on the top edge of a hollow tree, half a mile from our barn with its vulture chicks.  These look to be the same age as ours.  When I got too close, they dropped back into the tree with a drum-like thump.

Hollow tree nest

Even after they have fledged, the young hang around for several weeks, still being fed by their parents.  I guess if you are going to eat rotting meat for the rest of your life, it doesn't make much difference if it is "fresh" or secondhand. 

Note down traces- Click to enlarge

Our barn vultures the same day

Birds vs. Energy

Wind Farm - Wikipedia

A friend was recently reading about the bird deaths from wind turbines and asked how that compared to other sources of electricity The problem is that where ever we humans go, there is damage to nature as it was. It began when the first Homo species discovered fire and started to harvest the energy of wood. As we have gotten more efficient sources of energy, we have also become more efficient in disturbing the ecological system.

There is no question that we occasionally electrocute birds, and squirrels for that matter. Some years back a turkey vulture landed on the big old (1915) steel rig that holds the electric powerline from Powersite Dam to Ozark. It was electrocuted and the short dropped molten copper to the ground where is started a fire between two houses. Fortunately the homeowner saw it and we were able to extinguish it with the help of 3 fire trucks, so the vulture didn't get full revenge on humans for the lousy perch we had built.

There is no question that wind turbines kill birds by the thousands. There are all kinds of estimates out there and I don't recall the number given at a recent Audubon presentation. We are able to modify that with regulations that require factoring in the bird migratory pathways and the design of turbines. One reason you see so many in Western Kansas, in addition to wind patterns is the science involved in placing them where the migratory density is lowest. Also there is more known about the speed of the blades. Faster rotation up to a point produces more energy but beyond that point there is a rapidly diminishing return. Those slowly turning blades you typically see are actually moving at 80-90 mph at the tip!

There is no question that oil and especially coal mining kills far more birds that solar and wind combined. We could (and probably will) double or more the amount of wind power and still not reach the damage of oil for power alone, not to mention the far greater effect of burning coal. See the bird mortality data below compiled by US News and World Report.

As the link above explains, there is a wide range of results based on different methodologies as no common standards of measurement exist. Also, solar and wind based power are expanding so those numbers will go up. That said, these studies do demonstrate the hidden cost of coal and gas based power.


There is a far greater man-made or created killer of birds that we all tend to forget, Felis domesticus, the house cat that came along with our domestication of these predators into household companions. DNA studies suggest that its forbearer was the Near Eastern wildcat Felis silvestris lybica from around Israel and Saudia Arabia.


Nice indoor pets, they turn into ravaging mass murderers outside the house. The best estimates are 1.4 to 3.7 billion birds every year. Note that is a "b" not a "m" as seen with oil and gas.


As my mom used to say "You pays yur money and you makes yur choice." You can learn more about that choice at this US News and World Report article.

Thanksgiving Feast

In the November issue of Missouri Conservationist, ombudsman Tim Smith answered a question about why you don't see a lot of dead deer in the field.  "During warmer seasons, deer carcasses will “melt” into the ground quickly and can easily go unnoticed."  With "a little help from my friends" this is literally true.

Having watch a large dead doe's carcass virtually disappear over 4 days this summer, I was surprised how fast this occurs.  This last week we staked out a large frozen turkey that had defrosted earlier in a power failure, set up the game camera and a few days later watched the recorded action.

The banquet

King of the Mountain

Although there wasn't a vulture in sight, within 3 minutes the first turkey vulture arrived.  It must have been watching me turn on the camera.  There were 10 vultures within 5 minutes, recruited by the sight of their friends landing.  They took turns standing on the firm carcass.

Good reason for a bald head

They took turns feasting for the next 31 minutes, then suddenly flew off, leaving the field of vision clear for less than a minute.  Then the red-tailed hawk arrived and scoped out the field. 

"Yeah, just try it Buster"

Over several minutes several vultures returned, staying back a respectful distance.  The hawk remained in sole possession of the carcass for the next 30 minutes, occasionally glaring at the vultures.  After the hawk left, the vultures attacked the carcass for 10 minutes until the hawk returned. 

The hawk stayed this time for 18 minutes (dessert?) before leaving it to the vultures.  They shared the carcass for another hour before it turned dark and they called it a day.

The next three days there were occasional visits by a few vultures for several minutes at a time and an inspection by a neighbor's dog, checking out the bones which were picked clean.  On the fifth day, a red-tailed hawk made a final inspection of the carcass, looking at it nostalgically.  When I returned, I had trouble finding the remaining bones.

Click here to see the complete set of 16 full sized pictures.

Black Vultures - Day 15

The black vulture family in our barn now has teenagers.  They are displaying lots of attitude when I look in on them now.  The adult birds both care for the young and since they cannot be differentiated by appearance* I will call them parents.  They now stand by unperturbed by my presence, maybe even a little proud.  When one was sitting in the window opening by which it comes in and out, you can see that it watched me from six feet away, looking over its shoulder occasionally to check the chicks in the barn.

Vultures have no voice box so their vocalization is by an open throat hiss.  In this video you can hear the chicks telling me to stay away.  If you wondered how something so little could make so much sound, notice its body as it inhales and then strains, vigorously pushing the air through its throat.

Visitors are always expecting a stench - after all they are vultures.  In actual fact I have never noticed an odor in their nesting area in four years.  I use the term area rather than nest as they just lay their eggs on the bare ground.  Over their brooding period the eggs may be moved around in a three foot circle.

Soon our little teenagers will grow into an awkward phase of adolescence.  Coming soon to a blog near you.

*  Sexual dimorphism is the term of describing the obvious differences between the male and female of the species. Vultures lack these but have no apparent problem finding mates, so apparently they know the difference.

Pandora Sphinx Moth

  Photo by Drew Albert

Drew Albert of our Master Naturalist chapter found this beauty hanging out in a tower of the National Weather Service where he works.  This was a restricted area and it wasn't wearing an ID, but he turned a blind eye and a camera onto the trespasser.

This is a Pandora or Pandorus sphinx moth, Eumorpha pandorus.  It seems appropriate that it was hanging out at the airport as it resembles a stealth bomber that is painted in jungle camo, like Mother Nature had been watching too many Rambo movies that day.  They fly predominately at dusk on green to brown wings that can span 4.5 inches.  Their wing shape looks a lot like the somewhat smaller hog sphinx moth.

Hog sphinx, Darapsa myron - Chris Barnhart

  Janice Stiefel

The larvae are just as impressive as the adult.  They grow up to 4 inches long by feeding on grape species (Vitis) as well as Virginia creeper.  There is considerable variation in the colors of their various instars.  The last instar climbs down to the ground and burrows into the loose soil.  There it will pupate in the fall, forming the cocoon that will be its home until it emerges next year as a beautiful moth.

  Fifth instar - gkmarsh

The caterpillars will go through five molts, called instars.  Early instars have a horn like most sphinx moths, for example the familiar tomato horn worm.  Unlike their cousins, the Pandora's horn has a cute little curl.  This disappears in the fourth instar, replaced by a little eye mark.

Early instar - Erik Blosser

 Head tuck - Janice Stiefel*

Like many other caterpillars, their prolegs have special hooks which allow them to feed upside down, clinging to the underside of a leaf to hide from predators.  At times they will tuck their two front segments into the third, giving the otherwise some what pointed head a blunt appearance.  When they are threatened they use a vulture-like defense, vomiting up a sticky substance.

Pandora sphinx with parasites and wasp emerging - Jo Ann Poe-McGavin

It doesn't always turn out well for caterpillars.  In addition to their contributions to the food chain for birds, insects and even snakes, there are various parasites that utilize them as a nursery for their young.  The specimen above is still alive, but just barely.  It was infested by the eggs of a parasitic wasp whose young have just pupated and emerged.  The parasites preserve all the caterpillar's vital functions until the last minute to maintain their food source.  You can see a little wasp at the bottom, presumably newly emerged from the pupa.
 
 *  The late Jan Stiefel had submitted 779 photographs to Bugguide.net and over 129 Door County, Wisconsin moth records, which are documented with the state. She had served as editor of the "Wisconsin Entomological Society Newsletter" since 1999.

There is more information at the  uwm.edu/ website.

Black Vultures Fledge- They're Baaaack!

August 23- You again?

I stuck my head in the Black Vulture nesting stall to see if I needed to clean out anything and there the chicks were, looking none the worse for their outing.  If I hadn't gone all over the stall the day they fledged I would have thought I had overlooked them.

I had assumed that like robins and bluebirds, once they leave the nest they are gone.  The hawkmountain.org site says that they fledge at around 10 to 14 weeks but remain dependent on their parents for much longer.  Sometimes they are still being fed by their parents eight months later.  They also may hang with their parent's social group for several years. With this late teenager behavior I almost expected to see an X-box in the stall.

The hawkmountain.org  site has extensive information on black vultures.  Stay tuned for more adventures!

Owl Pellets

I received a gift of owl pellets from Ben Caruthers.  While this might not excite you, it got a rousing welcome from our friends in the 5th grade WOLF School.  I asked Ben for the backstory.

"The barn is on a cattle ranch where my father-in-law works as a cowboy. I asked the owner if I could place an owl nest box in the old barn. I had not seen any sign of an owl. This was just in the hopes that an owl would find the box and nest there. At the same time I placed a trail camera to monitor any bird activity. It took two years, but the barn owls finally showed up."

There has not been any sign that they have actually nested in the box, but they used it as a perch.  Several other birds have shown interest in the box including rock pigeons, European starlings, American kestrel, and squirrels. Turkey vultures have used the barn for nesting. Once when I went to check on the nest boxes there were two large, white turkey vulture nestlings. They spread their wings and hissed when I approached. I got out of there quickly so I didn’t disturb them further. I also didn’t want to experience their alert response. 

The most recent check I made of the owl box I got to see the barn owl above in person. It flew right over the top of my head!"

=========================================

Ben collected over one hundred owl pellets on the floor of the barn below the nest box and from two other cross beam perch areas.  He delivered them to me separated in paper egg cartons.  Note to self - don't eat any eggs shared by Ben.  The contents were dry for months and some had been cleaned by some clothing moth larvae described in this previous blog.

Barn owls are carnivores, specializing in mice, moles, voles and birds.  Since they swallow their prey whole, passage of bones through the intestine is impossible.  Even the thought of that hurts!  The food bolus goes first into a glandular stomach for digesting with enzymes, acids and mucus.  Next, on to the muscular stomach (gizzard) where it is mechanically mashed up and the digestible portion move down the tract.   Fur, bones, teeth and feathers are retained until they are hungry later when they will be compressed into a "pellet" pushed out.*

By now, I am sure you are anxious to see what is in a pellet. The photo above is a single pellet which also had some leg bones, ribs, etc.  With the charts below* you can begin to determine which rodents passed on (or in this case passed up) after encountering an owl.   Biologist can even survey rodent populations by studying the pellets in the area.

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* Hungry for more details?  Check out this World of Owl site.  More on studying owl pellets is at this site.  A key to identification is here.

Teenage Vultures

The black vultures are back.  For those of you who wondered how those small pale balls of fluff could ever become solid black, here they are as teenagers.  They are now on day 50, walking around and using their wings for balance but no longer as crutches.

Day 15

Day 1

Their nesting period lasts from 70 to 98 days after hatching.  The chicks of the past three years would make little effort to escape when I arrived at the door of the stall but this year's chicks have been hiding behind some old doors until the last few days.  Finally I have been able to catch them out in the clear on this video.

Once they have fledged they will make flights across the field and occasionally out of sight.  Soon they will be soaring with the family, but like some human post-teen children who come back home to live, they will depend on their parents to feed them for up to 8 months.

Vulture families remain tight knit, sharing communal roosts with several generations.  This serves as a gathering place when they go out foraging.  Once they have found a carrion treasure, they will generally exclude non-relatives from their communal meal.

More on this All About Birds link.