Turtles
It’s turtle time of year. The time of year when turtles are seen crossing roads, traversing backyards, and just about anywhere else you might look. The other day I was stopped at a traffic light and looked to my left. A large truck towing an even larger trailer was skidding to a stop in the turn lane. Just in front of the truck was a large snapping turtle crossing the road. When the truck came to a stop the passenger door flew open and a guy got jumped out and trotted up to the snapper, grabbed it and walked the turtle to the side of the road where a small pond was and released it. I thought to myself, turtles could use more friends like these two guys. I have done this very thing hundreds of times over the years. So what are turtles doing when they are crossing roads and wondering in backyards? Well, most likely they are female turtles who are looking for a place to lay their eggs. Turtles spend most of the life in water. In spring and early summer male turtles seek out females for mating. Male turtles in most species tend to be slightly smaller and have extra long front claws that help them hold onto the edge of the females upper shell during mating. Males also have a concave area on their lower shell (plastron) that fits over the domed upper shell (carapace) of the female. Once the male has mounted the female a packet of sperm is passed from the male to the female which will fertilizes the developing eggs. The female has a short window of time where she needs to find a suitable place dig a nest and lay her eggs. Unlike birds, turtles don’t incubate their eggs but rather they leave it to the sun warmed earth to incubate. The female turtle will leave her lake or pond and travel up to a half mile until she finds a place where the soil is soft enough to dig an egg chamber. Sandy soil is often chosen because it’s easy to excavate. Using only her back legs and feet, she begins the digging process by wetting the soils with extra water she has stored in her bladder. One scoop of her hind feet at a time she begins to dig the nest chamber. It’s a slow process that she can’t see because it behind her. If she is disturbed during this time she will abandon and head back for the water. A nest chamber of a Painted Turtle is no deeper than 3 to 6 inches deep, or the depth in which she can reach with her hind feet. In the chamber she will deposit 5-20 pink to white leathery eggs. Once she starts to lay the eggs the female usually isn’t scared off and is completely vulnerable to predators. Once the eggs are deposited in the chamber she takes great care to back-fill the chamber with dirt and tamp it down. She even goes as far as moving debris over the chamber to completely camouflage the location. Once this is done the female usually makes a bee-line back to the safety of the water. Just yesterday I watched a female painted turtle (see photo) dig a chamber and lay 6 eggs in less than 30 minutes. She may have several nests in one season but it’s usually several days or weeks between nesting. Now it’s up to the sun to warm the earth and incubate the eggs. This is the dangerous time. Most studies show that 70-90 percent of all turtle nests are predated by raccoons, skunks, domestic cats, dogs, opossum, fox, coyote and just about any other animal that has a nose good enough to smell the buried eggs. In most species of turtles, the chamber temperature during incubation determines the sex of the offspring. Generally speaking, warmer nests incubated at around 84-87 degrees F, produce mainly females. Cooler nests at 76-77 F, produce mainly males. Nests incubated at 82-84 F produce a mix of males and females. For the painted turtle the length of incubation is 70-80 days, so eggs laid now won’t hatch until September or October. If the weather is good when they hatch, the young will emerge from the chamber this fall and head directly to the lake. However later hatching young turtles will remain underground in their nest until the following spring before heading to the lake which starts the entire process all over again. Until next time…
Hummingbirds
Mid-summer can be a slow time in the wildlife photography business. Most of the nesting birds are done raised their young and have retreated to the forests and fields to feed on insects and live a few weeks of the good life before gearing up for migration. So in mid-summer I find that I turn to hummingbirds for photographic opportunities. Of the nearly 9,000 species of birds in the world, about 320 are a kind of hummingbird. (By the way, that is a lot.) The majority of these hummers are found in the tropical regions of the world. In North America there are 17 species of hummers with most of these found in southeastern Arizona. Sorry to say, we only have one species of hummer in the northland–the Ruby-throated Hummingbirds (Archilochus colubris). The ruby-throat is a tiny bird measuring only 3” long. Females are slightly larger than the males and have longer bills. An individual hummer weights only 2-3 grams; it takes 5 hummingbirds to equal the weight of a single Black-capped Chickadee and we all know how small the chickadee is. Ruby-throated Hummingbirds often appear to be gray in color when viewed in dim or low light but are bright green when seen in direct sunlight. They have specialized feathers that contain individual cells that will absorb sunlight and reflect only the green spectrum of the sunlight back to our eyes, making them appear green. Males have a throat patch of specialized feathers called a gorget. The gorget appears black in color until he turns to face you. When sunlight hits the gorget patch it lights up in a brilliant ruby red color as if someone has flipped a switch to a neon red light. The bright ruby color is also a result of reflected sunlight. The gorget is used to impress females for mating. The bigger and brighter the gorget the more the females are attracted. Hummingbirds received their name from the “humming” noise created by their wings whiz through the air. Hummingbirds flap around 50-60 times per second during normal flight and can reach up to 200 beats per second during courtship flights. (Try doing anything 200 times per second.) They can fly up to 50 mph and usually fly no higher than 300 feet. Hummingbirds can hover, fly up and down, and are also the only birds that can fly backwards. To power all of that wing activity, the hummers have very large hearts that beat at an amazing 1,260 beats per minute compared to our own heart that beats about 70 – 80 beats per minute. Their heart is so large it comprises one quarter of a hummers total body weight. They fuel all of their muscle activity with oxygen. They breathe 250 times per minute compared to our own respiratory effort of 12-18 per minute. To keep these flying machines going, hummingbirds have a metabolism that is 40 times faster than our own. They survive on top line fuel—fast acting sucrose (a kind of sugar) obtained from flower nectar. They consume up to 50 % of their own weight in nectar daily. That would be the same as you or I drinking a bathtub of soda daily. Hummers feed on nectar about every 10 minutes throughout the day but flower nectar is not the only food on their menu. Tiny insects such as gnats and flees make up most of their non-nectar diet and provide them with the protein not found in a sugar water diet. So for me, if it’s mid-summer, than it’s hummer time. Until next time…
Cowbirds
I love how people think of some birds as “good” and other as “bad”. They feel that some birds are actually nice and friendly while others are mean and ill-spirited. They even go as far as thinking that some birds are welcome at their feeders while others are not. Well, I’m not one of those judgmental people. I like all birds. In fact I have never met a bird that I didn’t like. The Brown-headed Cowbird (Molothrus ater) is one of those birds that many people don’t like and I might go as far as to say that some people hate this bird. Again, I don’t understand this kind of thinking because I am truly amazed by this bird. So why do some people hate this bird? Let me explain. The cowbird is a nest parasite. The female doesn’t build her own nest to lay her eggs in. No, instead, she finds the nests of other birds and relies on these “host” families to incubate and raise her young. During the breeding season a female cowbird will mate then slip off to parasitize other nests. More than 220 species of birds are parasitized by cowbirds. Of these about 140 species actually knowingly incubate and raise the young cowbirds. For years naturalist like myself and researchers have wondered why do these birds knowingly raise a young cowbird to the detriment of their own young. Studies indicate that birds such as warblers that raise a cowbird chick have on average 3 of their own while warblers who don’t have a cowbird chick raise 4 of their own so its obvious that the warbler is not benefiting from hosting a cowbird. A recent study which was modeled after a study originally preformed in the 1940’s gives us some insight into this conundrum. It turns out that cowbirds use mafia like tactics to insure they young are raised and it goes something like this. When a female cowbird finds a nest she will deposit one of her own eggs then she removes one of the host birds eggs. By the way, a female cowbird can lay up to 40 eggs in a single season which must be some kind of record because most birds usually can produce less than ten. In the study the researchers took the cowbird egg out of some of the warbler nests while in other nests the cowbird egg was left. In 56 percent of the nests where the cowbird egg was removed, the female cowbird came back and destroyed all of the warbler’s eggs and nest thus sending the message “if you don’t raise my baby, I will take out your entire family”. In the nests where the cowbird egg was left, only 6 percent were depredated. So this leaves the host birds with not much of a choice, either raise a cowbird chick or nothing at all. Now that is what I call a fascinating story. Until next time…
Seasonal Changes
We are coming up on a very confusing time of year for many wild critters. It’s a time when the birds are getting ready to migrate and frogs are preparing to burrow into the earth for the long cold winter. But that’s not the confusing part. The confusing part is when these critters start to do something that they normally do only in spring—they start to give mating calls. Each autumn this strange phenomenon happens. Birds such as the Northern Cardinal and American Robin perch up high in a tree and start to sing their breeding songs as if it were spring. If that’s not enough, several species of frog start to call from the shallow ponds. It’s like a mini-spring breeding season all over again. So why do they do it? Well it all has to do with something called gonadal recrudescence. Hold on, I know what you are thinking, don’t give up on this story just yet. Read on. Each spring birds, mammals, reptiles and amphibians use environmental cues to indicate when it’s time to breed. More specifically they use the amount of daylight (sunshine) available each day, kind of like a luminous calendar. The amount of light in a day is called the photoperiod. In mammals the length of daylight is perceived through its eyes. In birds and amphibians the daylight is perceived or absorbed right through the skull and or body. Either way a photoperiod signal is sent to a gland in the critters brain called the hypothalamus which is connected by a thin stalk to the pituitary gland. The pituitary gland sends out gonadotrophic hormone into the body which acts upon the testes of males and the ovaries of the females putting the bird or amphibian into breeding condition. It’s like turning on a breeding switch. During the breeding season the testes of male birds will grow several hundred times their non-breeding size and weight and become active in preparation of mating. A similar process happens in female birds. The ovary of the female bird swells and starts to produce ovum which is the beginning stages of egg development. After the breeding season the testes and ovaries of these birds regress or shrink and become inactive and the breeding season is over for the year. It’s important that this happens after migration because the extra weight and size during migration would only serve to use up more energy and slow the bird down during migration. However in late summer the photoperiod or the amount of available daylight matches the photoperiod of the spring breeding season and the critters hypothalamus picks up on this signal and is temporarily tricked into thinking its spring. This is where gonadal recrudescence occurs. Recrudescence means to break out anew after a dormant period and that is what happens. The testes of the males and the ovaries of the females temporarily start to swell and become active again. So for a short couple of days or maybe a week the birds and frogs are tricked into thinking it’s breeding season based on the available daylight (photoperiod) and the birds start to sing and the frogs begin to croak. It doesn’t last long before the photoperiod shortens as the days shorten and the hypothalamus is no longer stimulated and the puitary gland stops sending out hormones to the testes and ovary and the bird returns to a non-breeding condition again. So if you hear a bird singing from a tree or a frog calling from your local pond in late summer you can be thankful you are not as controlled by your hormones as the birds and frogs are. Or are you? Until next time…
Hummingbirds and Bats
Glancing at the old rusted mercury filled thermometer tacked to the wooden post, I could see that it was 101 degrees. And the worst part is, I am standing in the shade. A temperature over 100 is fairly normal for southeastern Arizona in August, which is where I am at this week. I am here at the hottest time of year to photograph some special critters–hummingbirds and nectar feeding bats. August is when both the hummingbirds and the bats are at their highest numbers that is because they migrate through this part of Arizona on their way south into Mexico. During this blazing hot afternoon I am working on photographing hummingbirds but after sun down I will be photographing bats. This is how each day goes, day after day for the past 5 days. Up until 1 or 2 AM with the bats at night then get a few hours of sleep before waking at 5 AM to photograph hummingbirds. In the eastern half of the country there is only one species of hummingbird. It is the Ruby-throated Hummingbird. It is a hardy species that has managed to colonize the entire half of the country well up into Canada. Here in Arizona there are 18 species of hummingbird. About 8 of these are fairly widespread and occur throughout the western half of the country while the rest are highly specialized and occur only in the southeastern corner of Arizona. These specialized species occur mainly in the tropics of Mexico and extend northward just barely reaching into the US in Arizona. This great diversity of hummingbirds is the reason I am here. As I mentioned I am set up in the shade of a structure that has a large metal roof and no walls. Just six tall wooden poles to hold up the corrugated metal roof. It took nearly a day to set up all the flashes, four in all, and work out the details of all the camera and flash settings to take pictures of hummingbirds. The object is to take hummingbird pictures and freeze their wings perfectly still while the bird is in flight. You see, if you take a regular picture of a hummingbird while in flight it’s wings flap so fast that not even my cameras fast shutter speed is quick enough to stop the rapid motion of their wings. In the amount of time my camera’s shutter opens and allows enough light in to expose the image, and closes again, the hummingbirds wings have flapped about a dozen times creating blurred wings. So what I am doing is fooling the camera by photographing in the shade. I have set up four high speed flashes to use as my primary light source. And now for the tricky part. I have set the flashes to give off a lot of light but only for a very short duration of time—about 1/3200 of a second. So when the hummingbird comes in and feeds at some flowers and I push the shutter lease, in the relative darkness of the shade, the camera’s shutter opens up and the high speed flashes go off. Only the short blast of light exposes the image not the daylight. So in other words the camera sees only what the flashes light up for that incredibly short moment of time and waa-la an image of a hummingbird with frozen wings. I love photographing hummingbirds partly because hummingbirds are one of my favorite birds also for the challenge they bring to making beautiful pictures. Hummingbirds are so very different from other birds and I love their quickness and agility. I also enjoy how they buzz from one flower to the next sipping the tiniest drop of nectar. What’s not to admire about this tiny bird? Next time… I will write about the nectar feeding bats.
Nectar Feeding Bats
When I left off last time I was sweltering in the 100 degree plus heat in the desert of southeastern Arizona near the Mexican boarder.
Molting
It’s molting time again. No this isn’t a bad county music song, it’s what’s happening with our backyard birds right now. At the end of summer and early fall most birds are molting. It’s not a bad thing. It’s when the birds replace their old worn out feathers with new feathers. Molting can be described as an orderly replacement of a bird’s feathers. There are a couple different kinds of molts. Complete molts are when all the feathers on the bird’s body, wings and tail will be replaced. This is a slow and orderly process replacing just a few feathers at a time as to not hinder the bird from flying or changing its appearance. These usually take place symmetrically so if the third primary flight feather is replaced on one wing it is replaced at the same time on the opposite wing. Partial molts involve only the large contour feathers on the birds body and not the wings and tail. Birds that have partial molts have two molts per year. One molt for the body alone and one for the body, wings and tail. The molts are usually spaced out about half way through each year. All birds molt but molts vary greatly from species to species. Some birds will molt only one complete molt per year such as the American Crow. At this time of year adult crows will replace all their feathers one by one and grow in new replacement feathers. It’s a slow process and since it’s only a couple feathers at a time most people don’t notice it. Sometimes you can see old worn out feathers next to shinny new feathers but that is about the extent in which you can see this process. American Goldfinch are undergoing a complete molt right now. The males loose their bright yellow and black feathers and are replacing them with dull green feathers. They will under go a partial molt in spring and return to their bright canary yellow and black colors. This usually starts in later winter. Only a small handful of birds have two complete molts per year. These birds are ones who live in challenging habitats and wear out their feathers very quickly. These include March Wrens and Bobolinks. These birds live in environments with rough vegetation which wears out their feathers faster than birds who live out in the open. Some birds will have just one complete molt each year, however like the American Goldfinch they will change colors over the year which seems a little contradictory. The European Starling is one of these birds. At this time of year they appear to be covered with white and brown spots. Gone is the dark, sleek coat of black feathers that shines purple and green in summer sunlight. During fall and winter the starlings look completely different, so much so that I have had people contact me and ask if they have some new bird in their yard because they haven’t seen this spotted bird before. The brown and white spots of the starling are only on the tips of the feathers and appear right after their one complete molt in late summer. During fall and winter the tips of the feathers wear off and by spring all the spots are gone leaving the bird back in its sleek coat of black feathers. A complete transformation without molting but instead worn away feather tips. The Northern Cardinal is the same way. In fall and early winter the male cardinals undergo a complete molt and replace all of their worn red feathers. However if you look closely in the winter they have a tinge of gray, especially on its back. That is because all of their new feathers have gray edges. The gray edge wears off during the rigors of winter and by spring time the male cardinal will again look bright red and ready to impress the girls without having to go through another complete molt. Another molts cardinals are doing right now is replacing their head feathers, leaving a lot of “bald” cardinal right now. Both the males and females will drop all of their head fathers at the same time exposing their dark skin beneath. This is another phenomenon that I am contacted about on a regular basis. Right now I have three cardinals coming to my feeders and all are missing their head feathers. It will take just a couple of weeks to grow the feathers back and return the cardinal to its former beauty. Until next time…
Whooping Cranes
I have just returned from a wonderful trip to see and photograph one of my favorite endangered species—the whooping crane. I’ve been following the story of the reintroduction of the Whooping Crane for about five years now and for the past couple of years I’ve been making the trek to see the birds and learn more about them in person. This year a small group of 13 enthusiastic birders joined me on my annual trip to central Wisconsin to see how this year’s young cranes were doing and how the preparation for their migration south to Florida was going. If you are not familiar with the Whooping Crane here is a little background. Once thought to number over 1,400 in the mid 1800’s the Whooping Crane dropped to an all time low of only 15 individual birds by 1941. This was due to loss of habitat, hunting and lack of environmental laws and education. As a result, the Whooping Crane was declared an endangered species in 1971 and several attempts were made to help recover the species. The first recovery project stated in 1975 and involved having Sandhill Cranes foster parent Whooping Cranes. The problem was the new Whooper’s didn’t mate with other Whooping Cranes and the project was scrapped in 1989. The second try at bringing the Whooping Crane occurred in 1993 by establishing a non-migratory flock near Kissimmee Florida. However the birds haven’t thrived and now the population is actually decreased so this plan was scrapped. The third and current program to reestablish Whooping Cranes stated in the fall of 2001. The decision was made to establish an eastern migratory flock. A flock that would migrate from the upper mid-west to Florida. Every year since 2001 about 15 to 20 young cranes are added to the flock. So far, to date, there are 69 Whooping Cranes in the eastern migratory flock. All of these birds are the result of the introductory efforts. This is how the process goes. Eggs are hatched and reared by costumed humans that look like adult Whooping Cranes. On the costumed human’s hand is a head and beak that looks like an adult crane. The costumes take advantage of the natural instinct in the young cranes known as “imprinting”. The first thing the young cranes see when they hatch is the costumed humans and think they are their parents. Once the chicks are large enough they are gradually introduced to the loud engines of the ultra light aircrafts. Eventually they will fly along with the ultra lights which are piloted by the costumed pilots so conditioning them to the sights and sounds of the aircraft is very important. What is really interesting is, they only need to show the young cranes the route to Florida, not back. The young return in spring to Wisconsin on their own. This past summer 11 pair of adult Whooping Cranes attempted to nest but none were successful. No one seems to know why there were no successful hatchings but you can be sure they are looking into the cause of this major hurdle. This year there are 14 young Whooping Cranes that will make the trip flying behind the ultra lights. Depending up the weather, the young cranes and their costumed human parents/pilots will be departing from central Wisconsin and heading south around the 17th of October. I wish them well and a safe journey. I will be following their progress. I have a deep respect for the staff and pilots who have dedicated their lives to returning this magnificent endangered bird back to the wild. It is their hard work and dedication that will serve to benefit us all by bringing back the most endangered crane species in North America. You can follow the progress of the young birds and their flight south by visiting www.operationmigration.org.
Mammals
There has been some very interesting news lately concerning the world’s mammals. First the good news. There now seems to be a consensus on the number of mammals that inhabits the earth. Over the years it has been generally
Migration
Lately I have been thinking a lot about migration. At first blush you might think migration is a simple and basic process, so much so that most people take it for granted and don’t give migration a second thought. Birds leave in the fall and return in the summer. Enough said, right? But that is not what I think of when I think of migration. I think of the incredible rigors of migration. The days, weeks and sometimes months of endless flying, traveling in areas the birds haven’t been before on their way to a place they haven’t been before or know anything about. The challenge of finding food during migration in unfamiliar and often dangerous territory is also a daunting task. Trying to avoid a multitude of hazards along the migratory route is another problem. These hazards include obstacles such as power-lines, radio antennas, tall buildings, air planes, and the ever more common wind turbines. To me, it’s amazing that any bird is successful in migrating these days. Migration is so difficult that of the species that migrate, only about 50 to 60 percent of the adult birds that are migrating will actually survive the journey. Compare that to non-migratory birds in the tropics which have a rate of 80-90 percent and you can see just how dangerous migration really is. Let’s start with the definition of migration. Most would agree that migration is best described as the predictable or seasonal movement of a bird from one region to another for the purposes of surviving or propagation. The key here is the predictable or season movement. This means that each year around the same date the bird will start to migrate and they will end up in approximately the same place each year. And the reverse will be true in the opposing season. Birds such as the American Goldfinch are really not true migrtors, but rather they just wonder around without a predictable destination or at a specific time. This is called nomadic. Some birds only move far enough to find food or open water such as waterfowl, these are considered partial migrators. Birds that travel hundreds or even thousands of miles to a specific destination on a regular time schedule is what I am most interested in. These are called true migrators. No one knows when or why birds started to migrate. There are several theories and of course we will never actually know. However we can be fairly sure migration started as a result of one or more of the following conditions; climatic change, lack of recourses such as food or water, competition for nesting sites, aggression or dominants of members of the same species, seasonal tracking of specific food such as fruit or nectar. No matter the reason, migration is a real natural phenomena. Here are some other things we know about migration. Bird populations can develop migratory behaviors and loose migratory behaviors fairly quickly. For example, when environmental changes occur that effects the reproductively of a bird species, migratory behaviors can develop dramatically fast; in just a few generations. House Finches are a good example of this. In their historic range these birds are sedentary or non-migratory. However in the early 1940’s House Finches were transported from California to Long Island, New York. The introduction was very successful and the House Finches colonized. However since the climatic conditions are very different from California to New York, the birds were under considerable environmental pressure to survive during winter. Within 20 years of the birds being introduced to New York, they started to migrate to get out of the winter. Although some of the birds did stay and remained sedentary many more started to migrate to the Gulf States and now they are considered a partial migrant. There are also good examples of highly migratory birds that no longer migrate once environmental conditions changed. Dark-eyed Juncos colonized Guadeloupe Island, which is over 150 miles off the coast of Baja California. Since the climate conditions are fairly stable on the island the birds had no reason to migrate as they do in their normal range. Now the population of juncos on the island is sedentary. So there you have it, a basic over view of migration. It’s best if we keep in mind that nature is dynamic and always changing. It has to be in order to adapt to changing environments and that is why Mother Nature is a survivor weather she is migrating or not. Until next time…