Singing in the Rain (Mockingbird Style)

Rain falling outside my window. Photo by Aaron N.K. Haiman

I few days ago, my daughter and I were standing in our backyard when it rather suddenly started to rain!

The rain was not a tremendous downpour, so we decided to stay out and enjoy the weather. And it turned out we were not the only ones to make that choice.

I was somewhat surprised to see a Northern Mockingbird (Mimus polyglottos) fly out of cover and up to the top of one of the trees near our yard. The reason form y surprise is that, most of the time, birds tend to seek shelter during wet weather. Exposure to wet weather generally means wet feathers, and wet feathers are cold making it harder for a bird to stay warm. A wet and cold bird then has to use more energy to maintain its internal body temperature, which means it will run out of energy faster. This in turn means that the bird will need to go out and find more food which is time-consuming, uses energy as well, and may expose a bird to predators. So, staying dry and warm seems like a good, general survival strategy.

A Northern Mockingbird fanning its tail in a similar way to the bird I watching in the rain. Photo by Aaron N.K. Haiman

However, this Northern Mockingbird had other ideas. It decided to ignore the many trees that could have provided the dense shelter of leaves or needles, and instead specifically choose a high and exposed branch with no leaves or shelter of any kind. In the rain, it started fanning its tail out and spreading its wings to catch the drops for a rain bath. It was wonderful to watch this bird enjoy the rainfall. And, as if to illustrate how much the bird really was enjoying its shower, it started singing! A bird singing in the rain!

This drove home a point that has been driven home for me many times, but still sometimes surprises me, and the point is this. Many birds are so well adapted to their environments that they often don’t need to guard and horde their energy reserves so jealously. They have the energy reserves to spend on getting a bit extra cold if it means getting some feather maintenance done. This birds was confident enough that it would be able to get warm, and get food, that it did not have to worry about the rain. It was even willing to get a bit extra wet and cold by taking some extra time to sing in the shower.

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Watching a Douglas’s Squirrel Harvester

A Douglas’s Squirrel sitting on a branch. Photo: National Park Service

In his “Wilderness Essays,” John Muir said that the Douglas’s Squirrel “…is the most influential of the Sierra animals, quick mountain vigor and valor condensed, purely wild…”

And a couple of weeks ago, while my family and I camped in Kings Canyon National Park, I got to see how some of this influence is wielded.

In the early morning, I spent a bit of time wandering through the forest around the campground. As I was exploring, and watching Mountain Chickadees and Brown Creepers and Williamson’s Sapsuckers and White-headed Woodpeckers, I heard a thud of something hitting the ground close to me. I paused and then heard another thud. I looked up and high above my head I saw a Douglas’s Squirrel (Tamiasciurus douglasii) moving through the branches of a pine tree.

The forests of Kings Canyon National Park are filled with Douglas’s Squirrels! Photo: Aaron N.K. Haiman

The squirrel was moving from branch to branch checking the various cones. It would climb out to the tips of the branches where the cones grow and carefully and quickly assess each cone to come to a decision on whether or not it was ready to be harvested. If it was ripe enough, the squirrel nibbled away any pine needles blocking the base of the cone, and would then chew through the stem of the cone.

Once it had the cone off the branch, the cone would fall from the squirrel’s mouth and plummet to the ground. At first, I thought that the squirrel had accidently dropped the cone. However, after watching this process repeat a couple of times, I realized the squirrel was intentionally dropping the cones, and attentively watching where they fell. After observing the fall of a cone, the squirrel would scamper to the next cone.

I watched this process repeat again and again for over forty-five minutes. The squirrel was very strategic in how it went about its harvest. It was clearly working its way down the tree from highest branch to lowest. It would run out a branch to check the cones on it, harvest the cones that it wanted, then run back towards the trunk. Then it would jump to the next lowest branch and repeat the check-and-harvest process. In this way, it systematically checked every branch on the tree.

In the time I spent watching it, this squirrel must have harvested and dropped at least twenty cones. In that time, it also took a break for a few minutes to stretch out on a branch and rest, it took a few shorter breaks to groom its fur, and it spent a bit of time calling out into the forest. I figured that once the squirrel had enough food down on the ground, it would come down and feast, but it never did. I had to carry on with my day, so I left the Douglas’s Squirrel to it’s.

When I returned home, I read up a bit on this harvesting behavior, and it turns out that my assumption that the squirrel would eat the fallen cones was wrong. Douglas’s Squirrels do harvest large numbers of cones, but they are for winter storage! Once the squirrel I was watching was done harvesting cones, it was probably going to come down to ground level and begin hiding all those cones away in various locations so that the squirrel can come back and dig them out once the snow is covering the ground and other food sources are scare.

Forests filled with, and shaped by, Douglas’s Squirrels. Photo: Aaron N.K. Haiman

And this is where a big chunk of that influence comes in because the squirrels never make it back to eat every cone that they stash. These uneaten cones, and the seeds they contain, are where new trees sprout, so by hiding cones and then leaving them, these squirrels are shaping the forest of the future! That is some serious influence!

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Wasp Mantidfly (yes you read that right)

Every now and again, I learn about a creature that I have never heard of before that so surprises me that I can’t stop thinking about it. The most recent occurrence of this was about a month ago when I stumbled upon a picture online of a species of insect that just does not seem possible. it is called a Wasp Mantidfly (Climaciella brunnea). Firstly, the name of this insect is one of those names that just gets better and better as you read through it. Secondly, the name of this insect fits its appearance perfectly. I mean look at this thing!

A Wasp Mantidfly (Photo Credit: University of Minnesota Extension).

Learning about this insect has just gotten better and better the deeper I have gone! And it starts with a bit of irony because while the name fits the appearance of this species to a T, with its very wasp-like black and yellow striping and narrow waisted body, its very mantis-like front legs, and its very fly-like wings, it is actually not related to wasps, mantids, or flies! Perfect, and I right!?!

The Wasp Mantidfly is one of about 400 species of Mantidfly (sometimes also called Mantisfly) found around the world with 13 occurring in the USA. They are actually in the family that includes lacewings and antlions. And these Mantidflies have evolved a ton of amazing adaptations!

The first set of amazing adaptations have to do with the larvae. The first is that most Mantidfly larvae are parasites that eat spider eggs. The larvae cannot get through the silk strands that a mother spider spins to wrap her eggs in. So, the larvae gets itself wrapped into the spider egg case as the eggs are being laid. How the larvae is able to do this brings us to the second amazing adaptation – hypermetamorphesis. Regular metamorphesis is when an organism goes through several distinctly different life stages in its lifecycle. A classic example is the butterfly that lays an egg that hatches into a caterpillar that forms a chrysalis that emerges as an adult butterfly. Hypermetamorphesis is when an organism goes through those same life stages and then some! In the Mantidflies, the larvae actually have a couple of forms with the first one being a long-legged and very mobile form, and then the second form being more grub-like. The first mobile stage allows the larvae to seek out a spider and grab on for a ride. The trait of riding around on another animal is a third amazing adaptation – phoresy. Phoresy is when one organism rides around on another organism. The Mantidfly larvae hangs around on the underside of leaves and other places that are likely to have a spider walk past, and when a spider does pass by they climb aboard. If the spider is a male, the larvae will ride around until the male spider mates at which point the larvae will leave the male behind and ride around on the female. Once the larvae is on a female spider, it gets carried around on the female spider until she lays eggs. At which point the larvae maneuvers itself so that it gets wrapped into the egg-case. Once securely inside, it changes in the more grub-like larvae form and then begins eating the spider eggs. The larvae remains inside the egg-case to pupate and then emerge as an adult Mantidfly that is able to chew its way out of the spider silk and go on with its life.

The adult Wasp Mantidfly, specifically, has a more amazing adaptations! One that it is a Batesian mimic. This means that its coloration has evolved to look like a dangerous wasp, but is in fact harmless itself. If you are curious about Batesian mimicry, I posted a video on my YouTube channel on mimicry. A second amazing adaptation comes into play when the adults are looking for mates which occurs in the spring. The males release an aggregation pheromone. This is a chemical that female Wasp Mantidflies can detect and that attracts them to the male. One advantage of these aggregation chemicals is that it may help the Wasp Mantidflies to determine if an insect is a potential mate or a wasp that they look so much like! Yes, Batesian mimics have to worry about mimicry too. And lets not forget about those incredible front legs! In an impressive example of convergent evolution, the Wasp Mantidfly uses its front legs in the same way that a Preying Mantis does which is to grab other insects to eat.

All in all, these creatures look like they might have been produced in Dr. Frankenstein’s laboratory, but are actually an amazing product of evolution, and I really want to see one!!!

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Invasive Mute Swans

Mute Swans (Cygnus olor) are a species that is growing more and more numerous, and this is a problem.

Mute Swans are the “classic” swan from stories and art. They are large and showy and beautiful and these traits are exactly why they have been introduced to North America. Birds were brought from Europe in the 1800s and released in parks, gardens, etc. as ornamental additions (New York was the original release area). These birds have since reproduced and spread across the continent as far north as New Hampshire, as far south as Florida, and as far as west as California.

Adult male Mute Swan (Cygnus olor). Source: USFWS digital library.

They are becoming problematic for several reasons. One is that they are quite aggressive, and will chase and bite humans if that human trespasses on the swan’s territory. Another is that they consume quite a bit of food. They are big birds reaching up to 25 to 30 pounds, and that means they eat about eight pounds of aquatic vegetation every day. That is food which is then not available to native birds, and it disrupts habitat for native birds, mammals, fish, and other species. And a third reason is that the swans are directly aggressive to other species of bird driving them off nests, breaking eggs, and killing the chicks of other species, and so displacing those other species from areas where they would otherwise live. With habitats becoming ever smaller and more fragmented, this can mean the native species can be left with no where to go.

These problems have all contributed to Mute Swans being added to California’s restricted species list in 2008. This listing means the birds cannot be imported, transported, or possessed in the state without a permit. This has not completely prevented the swans from beginning to become established in California. Small populations can be found in Petaluma and the Suisun Marsh. I suggest that removing this species while the population is still small is the best course of action. There is every reason to suspect that the population will grow, and as it does so, the problems listed above will become more and more apparent. However, control will become more and more difficult.

One interesting thing about Mute Swans in North America is that they do not migrate very much. There are certainly some, relatively short, seasonal movements that occur in some parts of the continent, but not much. Certainly nothing compared to the long migrations that Mute Swans in Europe engage in. The evolution of this behavior in a novel environment illustrates how different geographic regions can cause a species to adapt and change. This behavioral evolution could then lead to the evolution of a new species, if it persists and becomes dramatic enough.

So, what can you do to help native birds and habitats, and prevent Mute Swans from taking over? If you spot a Mute Swan in California, contact the California Department of Fish and Wildlife – Invasive Species Program by sending an email to: invasives@wildlife.ca.gov or calling 886-440-9530. Together, we can act as citizen scientists to gather data that tracks where these birds are and how they move around. This data will help us all make the best and most informed decisions we can about this species.

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V Formation Aerodynamics – A Birding Naturalist Video

Have you ever seen a v-shaped flock of geese fly overhead and wondered, why do they do that? In this video I share some information explaining this interesting behavior. I also talk about the other species that also fly in v-shaped flocks, and dispel an oft repeated myth.

If you enjoy the videos I am creating, two ways to stay informed would be to subscribe to the A Birding Naturalist channel and/or become a follower of this blog.

Eurasian Cranes (Grus grus) flying a v-formation (Photo courtesy of Wikipedia)

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Partitioning the Trees

A few years ago I wrote a post on niche partitioning among herons and egrets. That post was inspired by watching several species of herons and egrets foraging for food along Putah Creek near Davis, CA, and the resource they were partitioning into niches was food.

Recently, as part of my work at the Sacramento-San Joaquin Delta Conservancy, I encountered another example of niche partitioning by herons and egrets. This time, the resource these birds are partitioning into niches is nesting trees.

One of the grants that I manage at the Delta Conservancy is at the Cosumnes River Preserve and it includes and grove of large Valley Oak trees that many herons, egrets, and cormorants use as a rookery (a rookery is a colony of breeding animals, generally birds). One way that the various species have evolved to utilize the same trees, and yet avoid directly competing with each other, is for each species to utilize a different part of each tree to nest in.

Great Blue Herons typically nest on the very tops of the crowns of trees, Great Egrets typically nest only in the upper one-third of the canopy, Snowy Egrets typically nest in the middle one-third of the canopy, and Black-crowned Night-Herons prefer to nest in the lower one-third of the canopy (see the image below).

Niche partitioning of nesting locations within a tree by heron and egret species

I think this stratifying of nesting locations is amazing! Species have evolved to fill so many different niches, and so many niches can be divided into finer and finer gradations. I wonder if there is really any limit to how many species can evolve, and how complex an ecosystem can develop, in a give location.

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So You Think Being Transgender is Unnatural?

Homosexuality has been observed in just about every species it has been looked for. Transgender animals may not be widely known, but that may just be a matter of less interest in looking for them and/or writing about them.

There are certainly some animal examples that represent various forms of transgender animals in nature. One is the California Sheephead (Semicossyphus pulcher) which is a fish that is born female, and then can become male later in life. Another example is found in the Green Frog (Rana clamitans) that reverses sex in response to various external factors, and this has been observed in other amphibians as well. But both of these examples are in lineages of animals that are pretty distantly related to us humans.

Photo of two lions one is male sex (left), one is female sex (right), but both display male characteristics.

Well, research published a couple of years ago in the African Journal of Ecology is an example much closer to us. In a paper by Gilfillan et al. from the University of Sussex, five lionesses in Botswana have been observed to grow manes, regularly roar and scent mark, mount other females, and display other very male-like behaviors such as killing the cubs of rival prides which females lions just about never do but is very common for male lions.

This is a mammal we are talking about.

Lions that are female in their reproductive organs, but male in behavior and in some aspects of their outward appearance.

In the wild. In nature.

So, do you still think being transgender is unnatural?

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It’s A Bird-Eat-Bird World

My wife, daughter and I were in Berkeley, CA this weekend visiting my mom and some friends. One morning, while we were having breakfast and watching the visitor to the bird feeders hanging not far from the floor-to-ceiling windows, we witnessed a pretty dramatic event.

A female or juvenile Purple Finch.

As we eat our breakfast, a group of three or four Purple Finches were enjoying their’s. Suddenly, a California Scrub-Jay made an ambush attach on the feeder! It flew in through the branches of the Incense Cedar, and startled the finches into a bit of a panic. One of the Purple Finches (either a female of juvenile bird) made a very bad decision, and flew directly away from the incoming jay which meant it crashed into the big windows right in front of us. The jay flew past the feeder, not stopping at all, and landed on a table near the big windows. It seemed from watching the flight of the jay, that landing on the table had been its plan. The finch was on the deck, stunned by the impact with the window. The jay looked down, watched the finch for a moment to assess its condition, and then jumped down, grabbed the adult finch in its beak and flew away toward a large tree that we are pretty sure this bird and its mate have a nest in! That’s right, as if it was pretending to be one of the small hawks or falcons, the jay picked up the stunned Purple Finch and flew off with it!

California Scrub-Jay

This whole event only took a total of about one minute, but it got us all talking and thinking a fair bit about what we had just seen. First off, What a sight to see! All of us around our breakfast table were pretty surprised, impressed, and a few were taken aback at seeing a predator prey interaction at such close range. Secondly, I have never seen a California Scrub Jay prey on an adult songbird, before! I looked it up, and while there are reports of similar behaviors, they are not common. Thirdly, was driving a finch into the window the jay’s plan? The jay seemed like it was aware of the window, as its movements never put it in any danger of colliding itself. The finch was either unaware of the window, or was so frightened by the jay’s sudden attack that it forgot about it. So, did the jay basically hunt the Purple Finch using a window? Jays, members of the corvid family along with ravens, crows, magpies, and others, are highly intelligent and have been observed using tools in a range of settings. So, using a tool such as a known window location to incapacitate prey certainly seems possible.

Regardless of whether or not the window was used as a hunting tool, or if the jay just got lucky, this was a pretty impressive sight to see. And those baby jays had a very big breakfast of their own that morning!

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Information is Important

Information is important. With information each of us as individuals, and our society as a whole, can learn about the world. With information, we can all make decisions that make sense. With information, we can all discuss ideas.

Without information none of that is possible. Without information, we are, at best, at the mercy of our current, limited knowledge, and our base instincts. Without information we are, at worst, at the mercy of the limited knowledge and instincts of someone else.

This is why the gag order, and insistence that all reports and data be pre-screened before release to the public, issued by the President to the EPA are so concerning to me, and I think should be so concerning everyone else. This is exactly the kind of action that limits access to, and spread of, information. It will only hamper all of our abilities to operate as rational, critically thinking individuals. It is the kind of action that is put in place to control what we, as citizens, know and when we know it. This is censorship and it has no place in science or a free society.

#thisisnotnormal

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Shooting Bars Does Save Spots (sort of)

I have written about the conflict between Spotted Owls (Strix occidentalis) and Barred Owls (Strix varia) a couple of times before (here and here). The basic situation is that Barred Owls (generally native to eastern North America) have been expanding their range into the range of the Spotted Owl (western North America) for the past 40 years or so. The Spotted Owl has been declining for a long time and two of the three subspecies are federally listed as Threatened under the U.S. Endangered Species Act. The intrusion of Barred Owls is now a big problem for the Spotted Owls for several reasons.

A subadult Spotted Owl (photo by USF&WS)

One reason is that the total Spotted Owl population is smaller than the total Barred Owl Population, and small populations are more at risk of declines and extinction. Another reasons is that the Barred Owls are bigger and more aggressive than Spotted Owls and push the Spotted Owls out of nesting territories. Sometimes the Barred Owls are big enough and aggressive enough that they eat the Spotted Owl. Yet another issue is that the two species of owl are so closely related that they can hybridize and produce so called Sparred Owls. This genetic mixing has much more profound implications for the long term persistence of the Spotted Owl than the Barred Owl due the much smaller population size of the the former.

The primary solution that has been proposed to save the Spotted Owl from extinction has been to alter logging practices and set aside the old-growth forests that the Spotted Owls depend on. However, this has not been enough to halt the Spotted Owl decline. An additional plan that the U.S. Fish & Wildlife Service has been pursuing is the lethal removal of Barred Owls from areas where Spotted Owls are nesting or have nested in the recent past. From 2009 to 2013, USF&WS scientists killed approximately 90 Barred Owls. This had a marked effect on the Spotted Owl population. In areas where Barred Owls were removed, Spotted Owl population levels did not change any more than in areas where Barred Owls had never been observed. Also, territories that were held by the removed Barred Owls were fairly quickly re-occupied by Spotted Owls.

This result is a surprise to me. In my past posts, I was quite critical of the plan, and was skeptical that the removal of Barred Owls would actually benefit Spotted Owls. The results of the removal study suggest that this strategy might work to preserve Spotted Owls. But there are still problems.

An adult Barred Owl (photo by Ashley Hockenberry)

Spotted Owls respond well to the removal of their Barred Owl competitors. But how will these removals be maintained? Shooting Barred Owls takes a fairly considerable effort, so there is no way that this process can be enacted over the whole range of the Spotted Owl. It will not be possible to even do it over large areas. Instead, the only way that this plan will be able to be put into practice will be on very small areas of core Spotted Owl habitat. The other problem is one of time. To be effective, these core areas will have to be patrolled regularly, forever. New Barred Owls are perfectly capable of re-invading areas where the earlier Barred Owl inhabitants had been shot, and they will do so in short order.

So, much of my skepticism and critiques from my earlier posts still stand. I do not think that killing Barred Owls is a long-term solution for Spotted Owls on really any scale that will be useful for the survival of the species. It will simply require more time, effort, and money than anyone has to devote to the issue. That having been said, the fact that killing Barred Owls made any impact on Spotted Owls at all is more than I thought would happen.

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