Wednesday, May 30, 2012

Evening Walk with Cody, Snakes, Lizards and Hawks

On the evening of Memorial Day my dog Cody and I took a walk into the State Trust Land to the north of our property. A little rattler by the side of the road enjoyed the evening sun - the day had been surprisingly cool.

Nearly too cool for the Desert Iguana who seems to enjoy the triple digits more than all other reptiles around here. I'm still trying to catch one that's climbed up in a creosote bush to feed on leaves or flowers, but they are very fast and careful, trying to get close to a hole in the ground even if they don't quite disappear

Cody and I were really out there to check on the Red-Tails one last time. After one chick was on the ground on the 18th, and back with his sibling on the 20th, Randy and I found only one chick in the nest and the mother calling from a close by saguaro on the 25th. After that it got so windy and dusty that nobody wanted to be out there for a couple of days. By now, we expected that they were all fledged. Sure enough - in the picture you see the saguaro with the empty nest.

 But when I swung my binoculars left, to a mistletoe clump in the Ironwood Tree - there they were: two very grown up Red-tail chicks, still meeting a sunset curfew! I had noticed before that I was more likely to find the older chick in the nest at night than in the morning.

I found a feather and stuck it in my hat as a good bye. It's from a big raptor, maybe the male red-tail, the female's secondaries seemed much darker than this.

By popular request: Hawk-watching Cody. He looked very different when he pointed at the rattler, but I don't have the nerve to take a photo before calling him off.

Sunday, May 27, 2012

Unicorns Do Exist

Hi, I'm a Unicorn Mantis from Molino Basin, Catalina Mts, close to Tucson, Arizona. I am having a small identity crisis. I'm still a nymph, even though I'm more than 5 cm long, or would be, if I ever stretched my body, which I don't because the curl of my abdomen is part of my shape-dissolving camouflage.

 Here I am before I was discovered for stardom. My agent has good eyes, don't you think? Where do those grapevine twigs end and my endless legs begin? And when the wind shakes the vines I even add my own confusing little sway, almost sure to throw a predator or camera out of focus.

 So here I posed in the open for some beauty shots. I do know my angles! And always turn both my eyes to the camera - after all, I'm one of the few insects with binocular vision and a head that rotates on its neck just like yours. This unique ability also sets me apart from my youngest siblings as a sign of my maturity.

Far from being a pious 'Praying Mantis' like my Mediterranean cousin, I love Latin dancing and could conduct any symphony orchestra without a baton with my innate rhythm and great arms.

Let me not conceal my weapons, though: these are raptorial and deadly when unfolded. I don't even have to pursue my prey. The wariest moths and grasshoppers will walk right into my embrace.

 Just observe what it takes to make me disappear again! Just some dry branches, and a little motionless patience!

Now lets add a natural background that isn't just white: wouldn't you walk into the trap?

But back to my identity crisis: Am I an Arizonan (Pseudovates arizonae) or a Mexican Unicorn (Phyllovates chlorophaea)? Supposedly we are easier to separate as adults and the ranges of the species do not overlap, with the Mexican staying in Texas and the Arizonan living in Arizona.  But I need to ask the scientists who divided us not just into two species but into two distinct genera: was that politically motivated???

Pseudovates arizonae ootheca hatching.
22 July, 2014.
Rio Rico, Santa Cruz Co. AZ, photo and copy right Tony Palmer
Can you believe it, I just received some baby pictures from Tony Palmer via Facebook!
Nothing could soothe those identity problems better than this reminder of my roots. Weren't we adorable?

See more pictures and the rest of the story here

Sunday, May 20, 2012

Scary interlude

Two days ago before breakfast we went to visit the Red-tail nest. Something was different: the female wasn't  as usual high up in the sky, but in a saguaro close to the nest. Sporadically she screamed at me - that was not so unusual.

But then, there was only one lonely chick in the nest. It seemed to be the smaller of the two. Doesn't he look unhappy? Like he was left behind?

Sure enough, the other chick had left the nest. He was sitting not far away out in the open - looked very much like he had sailed off the nest, but couldn't really fly yet.

May 18th, 2012

Feisty and healthy looking, he threw himself on his back to show me his needle sharp talons when I approached. I have worked at raptor rehabilitation stations here and in Germany. We received many little guys like that. Even if they start eating, which they usually do, they often arrive with broken pinion feathers and don't learn to fly properly because those are not replaced before the next molt - in a year I believe. I checked him out and put him under a shady tree right next to the nest saguaro.  His mother was right there, if the sun didn't kill him, he had a chance.

But for two days, I wondered whether I shouldn't have brought him to a rehabilitation center. I do believe that a lot of chicks that well-meaning people pick up would survive just fine where they were found. I also knew that he was vigorous enough to fend off a coyote - they have easier prey right now and will not risk any injury. He was used to the sun because there wasn't much shade at the nest either. If he stayed under the tree he might also escape the great horned owls who seem to be hunting closer to our little mountain lately anyway. And yet...

This evening I finally made up my mind to find out what happened. I really dreaded going out there. Around sunset the adults are often nowhere to be seen, so at least I wouldn't upset them. From a great distance, I could see a chick standing tall in the nest. But - there seemed to be another dark shape with him. It could have been the ugly black plastic bag sticking up? Or the mother? I walked in a wide circle to get better light. Finally it was quite clear: the older chick had made his way back up into the nest, he (or she) had even reclaimed her favorite spot on the west side of the roost. She couldn't have climbed up, she must have flown, short wings or not. Maybe she managed to climb up the tree and then fluttered back from an elevated spot..

May 20th, 2012

Tuesday, May 15, 2012

Incubation Sonoran Desert Style

Yesterday I watched a male Curve-billed Thrasher bringing food to his nest in a Cholla Cactus. I was surprised to find the female actually on the nest, even though the chicks were clearly big enough to make a lot of noise. Her feathers were all fluffed up, the wings spread out, and she was panting strongly.

But she kept her chicks tightly covered by her body. At least until they heard me and worked their way out from under her wings to start begging with wide open yellow bordered beaks.

Like mammals, but unlike most other animals, most adult birds are homeotherm (with a few exceptions like hummingbirds and swifts undergoing temporary states of torpor) which means that they regulate their body temperature (42C or 105F in birds). To achieve this, they have to  maintain a constant equilibrium between  metabolic heat production and heat loss to the environment. Behavior is an important element of their thermoregulation, like seeking sunshine or shade. But birds and mammals have a great, if costly advantage over ectotherm animals like reptiles: they can regulate their body temperature independently of the environment through autonomous mechanisms. If the heat loss is greater than the resting heat production, muscle shivering is used to increase heat production. The insulation of the body is adjusted through changes in feather or hair position (piloerection) and altered blood flow to the skin and extremities.
With high environmental temperatures or during high physical activity  birds and mammals need to get rid of excess metabolic heat. They do that they employ evaporative cooling. Birds have no sweat glands, so their main cooling mechanism is the gular flutter  (vibrating the thin, highly vascularized skin of the neck in the breathing airstream) and panting. Avian thermoregulation is very efficient and allows birds to inhabit a wide range of habitats from the arctic ice to the Sonoran Desert heat.

 Developing eggs and young chicks (of the non-precocious species) need to be kept at the same core temperature of 42C for optimal development, but their regulatory systems are non-existent or underdeveloped. So the incubating parent has to provide the temperature regulation for eggs and young chicks. "Broody" birds develop special brood patches for this transfer of heat from their body to the eggs. In these areas of the bird's chest (abdomen and legs in Penguins) the feathers fall out to minimize the insulation between bird and eggs and an extensive vascular network develops in the skin because it is the blood that moves the bird's inner metabolic heat to the periphery and thus to the eggs. This is incubation as we people from temperate climates understand it.

At high-noon in  May and June in Tucson you could literally fry an egg on the sidewalk (if there was one). At 3 pm I measured the temperature in a cholla next to the nest: just about 100F. A few degrees below the temperature of the fully sun exposed surroundings, but still too high for chicks with no insulation and an immature thermoregulartory system My thrasher demonstrated that under heat stress, the incubating bird actually provides cooling to the nestlings by using her own evaporative cooling system and keeping close contact with the chicks. During the hottest part of the day she was so reluctant to leave them that I could have touched her.

Cavity breeders like woodpeckers and our kestrels have chosen a quite controlled environment for their off-spring. Especially when the cavity is in a saguaro, which is really just a massive column of water, nest temperatures stay much higher than the cool desert night and up to 25C under the outside temps when the afternoon sun heats the desert to triple digits (E.J. Braun, 1987). The Gila Woodpecker female above also has chicks, but since the temperatures climbed over the 100 mark, she regularly waits out the hottest part of the afternoon outside the nest in the shade.

 I went back to the trashers around 5:30 pm when the sun was lower and temperatures in the mid nineties felt quite pleasant to us Arizonans of over ten years. Sure enough, the chicks were sleeping in the depth of the scruffy nest bowl. 

 In a nearby tree the mother was preening her disheveled feathers and then took off for a drink from some saguaro flowers. She also regularly frequents the birdbath/quail block station in front of my studio window just around sunset. For at least the next three days, while temperatures were raising, the bird kept the exact same schedule. During this time the chicks grew in size and feathering at an amazing speed.

Galliform birds like quail use a different incubation trategy: Their precocious chicks can follow their parents within the hour after hatching. They are feathered,  can move to optimally shaded micro-environments, drink water, and do most of their thermoregulation by themselves.

But even in this harsh desert environment all kinds of niches are used and the success of doves and thrashers who breed in the most obviously exposed nesting sites seems surprisingly high.

References: Metabolism and Water Balance of the Gila Woodpecker and Gilded Flicker in the Sonoran Desert. EJ Braun, University of Arizona Press, 1969

Sunday, May 13, 2012

The last chick to fledge

On May 9th wildlife biologist and photographer Bruce Taubert set up a blind in our backyard. At this time only one kestrel chick remained in the nest. Although it was constantly chirping and begging, only the male kestrel came to feed it a couple of times between 8 am and 12 pm.  He was always in and out so quickly that it was hard to get a good shot, even with Bruce's great set-up. This was a day with very strange weather. Around noon the sky went from gray to black, there was dry lightning, and the wind grew into a steady gale of 50 mi per hour. Dust and sand were flying until the visibility was close to zero. I was glad that Bruce had given up his vigil around noon when there was nearly no activity around the nest.
The next day began with a clear Arizona sunrise. I was very happy to hear sounds from the nest where the last chick was demanding his breakfast. The feedings seemed to increase somewhat in frequency, maybe because there were more lizards out due to the better weather. We never saw the female again.

For three more days, the male kept supplying the single chick in the nest. This morning, on the 13th, I found the little guy sitting about 15 meters from the nest, sitting nice and upright in a bush, even though his eyes fell shut at times. Half an hour later he had disappeared. All day, there were ravens and the Cooper's hawk around...

 But at dusk, when the Night Hawks came through on their daily migration to the river, I heard a begging call. Sure enough, the chick was back, close to the nest in the dead Palo Verde, asking the falcon like passers-by for hand-outs.

His dad was right there with some prey, and he stayed close by after the feeding, so I'm very hopeful for the little guy.  

Tuesday, May 8, 2012

A Rescue

This afternoon the male kestrel was hanging around, not moving much, just intently staring. From the nest hole came begging sounds, but much weaker than before. I could see only one chick, and after a while I noticed that it was watching something on the ground in front of the saguaro.

There he was - one of the bigger chicks but still unable to fly and very tired. These chicks were nicely protected from predators while staying inside the saguaro arm that juts far out from the main trunk, but as soon as they leave the nest they are quite out in the open with nothing to climb up on and no way back.

 We had no intention to interfere with nature, we only chased the ravens off a couple of times....and got very attached to these little falcons in this hard environment. This guy was definite coyote bait where he was sitting. They come by very night to taunt our dogs.
So I caught him with my shirt and stuffed him into the photo bag. Randy got the ladder and held it steady so I could teeter on it's top steps reaching up to the saguaro arm. I dropped the chick unceremoniously on his brother's head and covered the hole with my hand until they settled down. No photos of that adventure - we both had out hands too full.

We were being watched closely. The male never left his perch. But it didn't take long and two heads appeared at the nest entrance and two chirping voices demanded food. Father obliged - he got at least two more lizards in the waning light and just tossed them in  - the chicks can do the rest by themselves now.
I have the feeling that this was one of the last times we have seen this family at the nest.

Growing Red Tail Chicks

The little Red-tailed Hawks have made great progress over the last week: they are standing upright, surveying their surroundings with keen raptor eyes. Both have inherited their father's light coloration. No rufous  morph this year.

He's the smaller one but he looks healthy and alert so he's hopefully able to compete for his share of the prey that the parents provide.

 The chicks producing so much waste now that the whole area is splattered white.
The smell is not lost on other meet eaters. Our dogs had to investigate - the chicks in their towering aerie watched them but didn't seem frightened. A turkey vulture also hangs around the nest every year.

While the chicks are growing up, the adult hawks are bringing more twigs and branches to the nest, maybe to cover up food scraps that fall into the nest. There is a twig of rather freshly green Creosote visible at the feet of the larger chick in here.

Mom arrived just after I had these shots. Time to go!

Saturday, May 5, 2012

Raptor update

The young Red Tails are still in their down feathers. They sit absolutely motionless and only the blinking of those huge eyes betrays that they are alive. There's one chick to the right -

The other one is facing to the back of the nest, with those ready to burst saguaro buds as a backdrop. It's getting rather hot now, in the nineties, and there is little shade, so this one is panting.

Mom still objects to my visits, so I only go once a week for a few minutes.

The little Kestrels, there are at least three, are now calling out to all birds that fly by - they aren't any better than I at telling  doves and night hawks from their parents than I am.

Since this afternoon, the two biggest ones are pushing their heads and upper bodies into the entrance. They look like they are ready to jump. I hardly ever see the adults. I guess they are so busy providing food for that ravenous brood.

All those raptor observations inspired me to paint the one desert species that I haven't seen in our backyard this spring, the Harris Hawk. These social raptors seem to prefer bigger trees like the old pines in Picture Rocks. They usually appear as a group when the young ones are already independent from the nest and beginning to hunt with the group.

Wednesday, May 2, 2012

Saguaro Kestrels

The nesting cavity is in the left arm of the right Saguaro. The female Kestrel is sitting in the dead Palo Verde on the left
 There is another raptor family that is even closer to my heart than the Red-tail Hawks: our backyard American Kestrels whose nest is only about 50 yards from my studio window. My reluctance to write about them earlier stems from a sad experience a couple of years ago when not only the chicks from the same nesting location fell victim to ravens, but the valiant, protective little male was also killed when he flew head-first into a cholla cactus. But the old Flicker cavity with the slightly enlarged entrance attracted a pair of Kestrels again, and maybe it's even the female that nested here before.

Photo by Ned Harris

During their 'Honeymoon' in late January, the pair was very noisy and obvious. When we were having breakfast on the patio we were constantly treated to the females high-pitched keerrr-keerrr and the males sharper kick-kick-kick....

They had their favorite spot close to the Saguaro cave on an old, dead Palo Verde. We leave dead trees to decay naturally and a lot of birds really appreciate these easy perches with great overview. Often, there is a quail, a dove and a thrasher already in line for this prime spot when the kestrel leaves for a hunting trip.

By mid February, the female spent most of her time close to the nest leaving the hunting to the male. They were still mating often and she didn't seem to be incubating any eggs yet. During my studies in the Arctic I learned that female Terns that are pregnant with eggs cannot fish - the high impact dive into the water would jeopardize the eggs. So the male faithfully feeds her for a couple of weeks.

He just presented her with a lizard
 It seems that our Kestrels followed similar precautions. It got much more quiet when she actually began to sit on the eggs (as far as I know raptors start incubation as soon as the first egg is laid, which accounts for the size-differences of the chicks.)

 The Gila Woodpeckers who had moved into a hole in the same saguaro were taking turns incubating, but the Kestrel female did the job alone. She regularly escaped the narrow cave to preen on her perch. She now had obvious brood patches on her breast where the feathers were thinned out to allow optimal heat transfer from her body to the eggs.

 While she was incubating, she also ate the lizards that the male delivered on her perch.  Eventually, this changed and she took the prey from him to carry it into the nest. From the way her tail was sticking up awkwardly in the entrance hole I guess she was now feeding the prey bite by bite to small chicks in the cave.. Fussy eaters: she had to carry the lizard tails away after the meal. Later in March, I saw the male trying to bring a big lizard into the hole himself, but he didn't succeed and carried it into a nearby tree where the female eventually joined him to retrieve it.

 By mid April the female was also hunting herself. From then on the diet also included small birds. Although this pair is usually very quiet around the nest, we witnessed some drama when the male pursued the Red-tail hawk in the air - dive-bombing him for over 15 minutes.

Another time a mob of thrashers, doves, cactus wrens, gila woodpeckers and verdins  congregated in an Ironwood tree and the male kestrel was diving very low....I thought they were mobbing a ground predator, but it turned out that  a huge Cooper's Hawk had landed on the lowest branches of the tree.
And of course there are the ravens who are now attracted to the saguaros not only to steal nestlings but also to nosh sweat nectar from the flowers. I must admit that I have sicked the dogs on the ravens now numerous times and the smart bird seem to learn that it's unpleasant to visit.

 An unexpected disturbance happened when a hot air balloon, out of gas and overloaded, made an emergency landing on our land close to the nest. After that the kestrels lay low for the rest of the day, but by late afternoon the urge to feed the hungry brood was stronger than their fear. While raptors are known to leave a nest with eggs after a disturbance, the bond seems much stronger when the chicks are hatched. 

All through April, the kestrel chicks have been growing in the narrow cave. They are finally old enough to eliminate white sprays of uric acid out of the entrance, so the ground now bears the white splatter characteristic for all raptor rookeries. Sometimes I can see a big black eye surrounded by white fluff peering out of the dark, and at other times there is a wild tangle of short tails and stubby wings visible. They are getting big for their nursery!

 Looking through my pictures I notice a steady improvement over the three months of observation. This has nothing to do with my skills or my camera's capacity. It's that the birds have become much more trusting over time, so I can now approach the nesting saguaro as closely as 15 feet while the female is calmly watching.