Wednesday, November 18, 2009
Sunday, November 15, 2009
How many points on a buck?
It's rutting season, and as a result it seems like deer have been everywhere. It's the time of year males get to show off their antlers, and as a result I've had several discussions about how many "points" a buck has. A point is each tine on the antler, including the brow tine, which sticks straight up near the base of the antlers. Someone will say they saw a four-point buck, and the debate is whether that means four tines total or four tines on each side.
A little research has shown that traditionally you count all the points on the antlers. This makes sense to me, since antlers are not always even on both sides, so it may be possible to have a seven pointer who has three tines on one side and four on another. The confusion comes in the fact that some hunters, particularly on the west coast, use the other method. So what is traditionally called an eight point buck could also be called a western four pointer. Follow all that?
A little research has shown that traditionally you count all the points on the antlers. This makes sense to me, since antlers are not always even on both sides, so it may be possible to have a seven pointer who has three tines on one side and four on another. The confusion comes in the fact that some hunters, particularly on the west coast, use the other method. So what is traditionally called an eight point buck could also be called a western four pointer. Follow all that?
The buck in the photo above is an eight-pointer. He's got three prominent tines, plus the two brow tines which are easier to see if you enlarge the picture by clicking on it. The other question I've had come up several times is whether or not the number of points is related to age - ie, do older bucks have more points? The answer is, someone surprisingly, no. It turns out the number of points has more to do with genetics and can also be influenced by diet and overall health of the deer. That makes sense - if you're a healthier deer you can "afford" to put more energy into larger antlers.
For white-tailed deer, common over much of North America, bucks can get up to sixteen or more points. On San Juan Island, we have mule deer, and their antlers are a little different. Their antlers fork as they grow rather than branch off the main shaft, and from what I can tell they don't usually have as many points as white-tails.
For white-tailed deer, common over much of North America, bucks can get up to sixteen or more points. On San Juan Island, we have mule deer, and their antlers are a little different. Their antlers fork as they grow rather than branch off the main shaft, and from what I can tell they don't usually have as many points as white-tails.
The other afternoon when I was out near sunset there were probably about fifteen deer grazing the prairies near the south end of the island. The buck pictured above was the largest male I saw, but mostly they were females. With the golden late afternoon light and some remnant clouds from our weather earlier in the day, this silhouette shot turned out to be a beauty:
Here's another pair of does that lifted their heads to check me out before returning to their grazing:
Despite the beautiful photo ops of the deer, my prized photo of the day was actually of a bird. I only see them occasionally and they've never let me approach close enough for a photo until now - the northern shrike!
The south end of the island is actually a pretty reliable place to see the shrikes this time of a year, as I think we have a couple that overwinter there. They're still a treasured find for this birder.
It was a beautiful afternoon outing, and my last on San Juan Island for the calendar year! I've headed south for at least part of the winter and arrived in Portland, Oregon last night. My heart lies in the islands, but Portland is where I grew up, and it will be nice to catch up with family and friends over the next little while in addition to visiting some of the local natural areas with a keener naturalists' eye. Stay tuned as my future posts, over the next few weeks at least, will feature some new places and different critters!
Wednesday, November 11, 2009
Orcas in November - Including A New Calf!
I haven't seen the orcas since October 9th, and I just felt like surely I had to see them one more time before calling the season truly over. I had to wait a little longer than expected, but today was that day!
Thanks to a report of the whales being heard on the hydrophones, I called a few friends and then headed out to the westside to see if I could find them. Before long the word had spread and I was joined by about a dozen other "orca-holics" as we watched J and K Pods head south past Lime Kiln.
It was exciting to see the whales, but even more exciting was the fact that we saw what is almost certainly a brand new calf! It was traveling with J28 Polaris, who at the age of 16 would be a first-time mom.
Thanks to a report of the whales being heard on the hydrophones, I called a few friends and then headed out to the westside to see if I could find them. Before long the word had spread and I was joined by about a dozen other "orca-holics" as we watched J and K Pods head south past Lime Kiln.
It was exciting to see the whales, but even more exciting was the fact that we saw what is almost certainly a brand new calf! It was traveling with J28 Polaris, who at the age of 16 would be a first-time mom.
At first we noticed what some of us refer to as a "nursery group", in this case one female with several youngsters that seemed to be a couple of years old at most. Often one mom will babysit other little ones and the calves will play together. When we saw that the adult female was Polaris, we assumed she was probably babysitting her younger brother J44 that was born earlier this year, which she has been seen doing before. There have been four calves born this year (two in J-Pod, including J44, and two in L-Pod), but all of a sudden one popped up next to her that just looked too small to be 10 or so months old, as the J-Pod babies are. Here's J28 and the new calf next to another youngster that's a little bit older (and bigger):
Several of us that keep close tabs on the whales have earmarked Polaris as a likely future mom since she is about the age most females have their first calf. After a few years of anticipation its exciting to finally see her with a little one of her own. There has to be a few more sightings before the calf's mom is confirmed, so it's not 100% yet, but it sure looked that way! The calf being new has been confirmed, and the Center for Whale Research has designated it J46.
Right away some people were spectulating the calf's father might be L57 Faith, an adult male that passed away last year that had a known affinity for J-Pod females. He traveled with J-Pod for all of the summer season in 2008 before he was last seen last November. He was often seen following J28 around, hence the speculation he's the father. With a 17 month gestation period, its certainly possible.
These next two shots are a little blurry, but I'm posting them anyway because they show what look to me like fetal folds on the back of the calf. Notice how the head and back don't look perfectly smooth. You may want to click to see the larger version. This is something you commonly see in newborns before their skin smooths out after being in the womb.
Right away some people were spectulating the calf's father might be L57 Faith, an adult male that passed away last year that had a known affinity for J-Pod females. He traveled with J-Pod for all of the summer season in 2008 before he was last seen last November. He was often seen following J28 around, hence the speculation he's the father. With a 17 month gestation period, its certainly possible.
These next two shots are a little blurry, but I'm posting them anyway because they show what look to me like fetal folds on the back of the calf. Notice how the head and back don't look perfectly smooth. You may want to click to see the larger version. This is something you commonly see in newborns before their skin smooths out after being in the womb.
The orcas weren't the only wildlife out in Haro Strait, either! In addition to lots of seabirds and hordes of rooster-tailing Dall's porpoise, this Steller sea lion came by and took a look at us:
Monday, November 9, 2009
Gull and bait fish
I've been meaning to post this picture for a while (I took it earlier this summer), but I always end up blogging about something else. Today's the day!
I was out watching the sunset, and a rhinoceros auklet was diving and feeding on bait fish, perhaps to take back to its chick. Often, they will capture their last fish of the day and then carry it to their nesting site, which is often miles away, under the cover of darkness so predators don't find their nest.
Gulls will often come in and take advantage of an auklet or other diving bird that herds a school of small fish near the surface, hence bringing the food within reach of the surface-bound gull. I see this all the time, but what made this particular encounter so unique was all the fish bubbling to the surface around the gull as they made an effort to escape the auklet.
I was out watching the sunset, and a rhinoceros auklet was diving and feeding on bait fish, perhaps to take back to its chick. Often, they will capture their last fish of the day and then carry it to their nesting site, which is often miles away, under the cover of darkness so predators don't find their nest.
Gulls will often come in and take advantage of an auklet or other diving bird that herds a school of small fish near the surface, hence bringing the food within reach of the surface-bound gull. I see this all the time, but what made this particular encounter so unique was all the fish bubbling to the surface around the gull as they made an effort to escape the auklet.
It must be an interesting life to be a gull. As a fellow naturalist put it, they pretty much make a living by waiting for someone else to get food. Then they find a way to steal or otherwise get some of it. Scraps stolen from seals, sea lions, or whales; food scavenged from humans; or in this case, fish schooled to the surface by a diving bird. Hey, whatever works!
Friday, November 6, 2009
Hearing in Marine Mammals
Today was the annual Marine Naturalists' Gear-Down, an end-of-season lecture series hosted by The Whale Museum. While there was a lot of great information shared, I thought I would focus this post on one interesting fact I learned and have since been pondering (and reading about further in a marine mammal biology textbook).
Our first speaker was talking about the adaptations required by marine animals to deal with the conditions of oceanic life. He made an interesting point when talking about hearing underwater. Evolutionarily speaking, animals originally had ears designed for hearing in the water, but as animals moved to land there had to be changes in the structure of the ear to deal with hearing in air. Humans, like all terrestrial mammals, have air in the middle ear, which makes us great at hearing sounds transmitted through the air. If, however, we have our heads underwater, our hearing is impaired due to impedance mismatch, which basically happens when sound switches from one medium to another. When sound going through the water encounters the air in our middle ear, it impairs our ability to hear it clearly or determine which direction its coming from.
Marine mammals evolved from terrestrial mammals, so their ears still have the basic structure designed for hearing in the air. How, then, have they adapted to hear so well underwater? They've had to find a way to overcome the impedance mismatch caused by the air/fluid barrier.
Toothed whales spend all their time underwater and have "solved" this problem by receiving sounds directly to their inner ear not through their external ear canal but through the fatty tissue of their lower jaw, which conducts sound in a similar manner to water. But what about pinnipeds, which need to hear both in the air and underwater?
Our first speaker was talking about the adaptations required by marine animals to deal with the conditions of oceanic life. He made an interesting point when talking about hearing underwater. Evolutionarily speaking, animals originally had ears designed for hearing in the water, but as animals moved to land there had to be changes in the structure of the ear to deal with hearing in air. Humans, like all terrestrial mammals, have air in the middle ear, which makes us great at hearing sounds transmitted through the air. If, however, we have our heads underwater, our hearing is impaired due to impedance mismatch, which basically happens when sound switches from one medium to another. When sound going through the water encounters the air in our middle ear, it impairs our ability to hear it clearly or determine which direction its coming from.
Marine mammals evolved from terrestrial mammals, so their ears still have the basic structure designed for hearing in the air. How, then, have they adapted to hear so well underwater? They've had to find a way to overcome the impedance mismatch caused by the air/fluid barrier.
Toothed whales spend all their time underwater and have "solved" this problem by receiving sounds directly to their inner ear not through their external ear canal but through the fatty tissue of their lower jaw, which conducts sound in a similar manner to water. But what about pinnipeds, which need to hear both in the air and underwater?
This harbor seal pup is adept at hearing in the air and underwater, due to a very interesting adapation
It's theorized that most pinnipeds primarily receive underwater sound through bone conduction, which means that sound reaches the inner ear by resonating through the bones in the skull. Some human hearing aids actually make use of bone conduction. This process isn't very well understood in pinnipeds, since orienting the direction of the sound must still be difficult. These pinnipeds then hear sound in air via the typical pathway through their external ear canal.
Different pinniped species have different hearing abilities in air/water depending on their life history. Elephant seals have sharper underwater hearing, whereas sea lions have better hearing in the air. Harbor seals, however, get the best of both worlds. As our speaker shared today, harbor seals actually have a mechanism to fill part of their middle ear with blood (a fluid which transmits sound more like water than air) when they are underwater to better receive sound. When they are at the surface, this blood drains, restoring the air to the middle ear and allowing them to hear better in the air. Since harbor seals use the external ear canal to hear underwater instead of bone conduction, they have better underwater directional sensitivity than other pinnipeds.
The biologist in me is fascinated by this kind of thing....
2018 Update: I continue to get inquiries about this post years later! Unfortunately I don't recall who the speaker was, but did find this reference in the book Sensory Ecology (pages 271-272) that describes this theorized mechanism a bit further:
https://books.google.com/books?id=6lTxBwAAQBAJ&printsec=frontcover&dq=sensory+ecology&hl=en&sa=X&ved=0ahUKEwjC9ai_wI3aAhUUwGMKHc9XBWgQ6AEILzAB#v=onepage&q=harbor%20seal%20blood&f=false
Different pinniped species have different hearing abilities in air/water depending on their life history. Elephant seals have sharper underwater hearing, whereas sea lions have better hearing in the air. Harbor seals, however, get the best of both worlds. As our speaker shared today, harbor seals actually have a mechanism to fill part of their middle ear with blood (a fluid which transmits sound more like water than air) when they are underwater to better receive sound. When they are at the surface, this blood drains, restoring the air to the middle ear and allowing them to hear better in the air. Since harbor seals use the external ear canal to hear underwater instead of bone conduction, they have better underwater directional sensitivity than other pinnipeds.
The biologist in me is fascinated by this kind of thing....
2018 Update: I continue to get inquiries about this post years later! Unfortunately I don't recall who the speaker was, but did find this reference in the book Sensory Ecology (pages 271-272) that describes this theorized mechanism a bit further:
https://books.google.com/books?id=6lTxBwAAQBAJ&printsec=frontcover&dq=sensory+ecology&hl=en&sa=X&ved=0ahUKEwjC9ai_wI3aAhUUwGMKHc9XBWgQ6AEILzAB#v=onepage&q=harbor%20seal%20blood&f=false
Wednesday, November 4, 2009
2010 Photo Calendars
It's amazing that 2010 is just around the corner, isn't it? Every year I put together a wildlife photo calendar, but this year I decided to do three with different themes: wildflowers, orcas, and birds. Since many of these photos have been featured on my blog, I thought I would link to them here. Click on a calendar to see all the photos for every month. The holiday gift-giving season is just coming up quickly, or get one to enjoy yourself! At checkout use the coupon code 10CALENDARS9 to get 10% off your order.
Sunday, November 1, 2009
Insect IDs
I've had some time to sit down with my new field guide (Insects of the Pacific Northwest by Peter and Judy Haggard) and have been successful in identifying some insects from my photos. There are some cool looking critters to share with you today!
This first one is one of my favorites for its interesting shape and unique coloration. (It was also relatively small at about 10-15 mm long, which made it more pleasant to approach than some of the larger specimens below. I'm not exactly an entomophobe, but I do believe in giving insects their space and hoping they give me mine!) From the shield-like shape I was immediately able to narrow it down to a stink bug (Family Pentatomidae), but the colors looked nothing like any of the photos in my guide. By referencing The Bug Guide, I was able to learn that its actually a stink bug nymph (Chlorochroa spp.):
Some insects, like butterflies, go through complete metamorphosis, progressing from an egg to a larva, then a pupa, then an adult. Others, like stink bugs, go through incomplete metamorphosis, hatching from an egg to become a nymph, then becoming an adult after one or several molts (instars). The fact that you can encounter a wide variety of nymphal stages in addition to the adult stage of an insect will make identification much more difficult, I can tell....
Aside from the charismatic butterflies and moths, the other large, common, distinctive insect group we often encounter is the order Coleoptera - the beetles. My field guide has a nice introduction at the beginning of the beetle section:
Coleoptera is the largest order in the animal kingdom and, with approximately 290,000 species described, contains an estimated 37 percent of all known insect species. More than 23,700 species have been recorded in the United States and Canada. Approximately one-third of the total number of insect species found in the Pacific Northwest are beetles.
This first beetle, pictured above, is a golden buprestid (Buprestis aurulenta) of the metallic wood-boring beetle family. In addition to its remarkable iridescent coloration, notice the four longitudinal grooves that run down each wing, another identifying mark.
The next one, pictured below, is a tiger beetle (Cincindela spp.). There are several similar species that vary in how green/brown the body are as well as the particular yellow markings on the wings, so I'm not sure which particular species this is. The field guide notes that they can be difficult to approach, and indeed this one was running when I saw it. This is the only photo I was able to get of it - I'm lucky it turned out as well as it did!
This next beetle I at first thought was either a ground beetle (big and black) or stag beetle (large jaws), so I was surprised to figure out that it was also in the tiger beetle family, although in a different genus. This is the flightless tiger beetle (Omus audouini). The mouth parts are what I immediately noticed, but upon closer examination I also looked at the shallow pits on the wing covers.
Moving on from beetles, here is a common fall critter that I've always heard referred to as a woollybear caterpillar. Turns out this is accurate - its a larval banded woollybear (Pyrrharctia isabella), that will eventually metamorphose into a tiger moth. According to an old wives' tale, the width of the orange band in the middle will tell you how cold the upcoming winter will be. Hmm, this band doesn't seem to be too wide - are we in store for a milder winter than last year?
Here is another closely related species - the larva of a rangeland tiger moth (Platyprepia virginalis). It's funny that I recognize many of the tiger moth larva, but not the boldy patterned adult moths.
There's nothing quite like picking up a new field guide and, while flipping through it, finding something that I haven't been able to identify anywhere else. As I've expanded my horizons over the last year and a half from birds and marine mammals to also encompass wildflowers, mushrooms, and insects, I've experienced this joy of identifying a new species several times - they are very much "Ah-ha!" moments. This last photo was one of those moments, the very first thing I identified using my new book - and I didn't have it down as being insectoid at all!
I thought this was some kind of fungal parasite when I found it growing on these plant leaves this summer. Take a look:
I thought this was some kind of fungal parasite when I found it growing on these plant leaves this summer. Take a look:
It's actually a gall formed by a gall wasp (Family Cynipidae). They're tiny wasps that are hard to find or identify, but each species lay their eggs on a particular host plant, and as a result a distinctive looking growth (the gall) develops in which the larva feed. The galls are the easiest way to detect and identify the species. The one pictured above is the rose leaf gall (Diplolepis polita). So THAT'S what that thing is! Amazing.
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