Wednesday, February 29, 2012

American Goldfinch (Spinus tristis) Back After Absence

Male goldfinch in breeding plumage stops by for a drink.
Photo by Brad Sylvester. Copyright 2010. Do not copy.
In the winter of 2010-2011 and the spring and summer of 2011, we had a decided absence of American Goldfinches (Carduelis tristis or Spinus tristis) despite having had many of these colorful little birds in previous years. I am very happy to report that they are back this winter. They have been visiting our thistle feeder in good numbers for several months and appear healthy.

The goldfinch is one of the more brightly colored summer birds that visits our backyard feeders. They are also quite vocal and their twittering can be heard from the trees surrounding our yard as they prepare to swoop in on the feeder and take their turn.

American goldfinches swarming a thistle feeder in February.
Photo by Brad Sylvester. Copyright 2012. Do not copy.
As the regular author of a bird watching column for Examiner.com (Manchester Bird Watching Examiner) for the past several years, it seems like it's about time to start adding more of the birds that live in my yard to this blog. There are well over 200 species of birds that live at least part-time in New Hampshire. Even excluding seabirds and those with specialized habitats, I should be able to log a very large number of species in my yard. Birds should be second only to insects and possibly spiders for total species counts by my estimation, at least until we start considering microfauna.

Although American goldfinches may shift their range north or south with the seasons, they are always present as a species in New Hampshire and live in my yard year-round. They are active bird feeder visitors, preferring thistle seed to all other offerings. Although they pair up for the summer breeding season, in winter they tend to travel in small flocks travelling around from food source to food source.
The American goldfinch is sometimes called the wild canary because of its bright yellow color and small size.

Lifespan: The Cornell Lab of Ornithology lists the oldest known American Goldfinch at 10.5 years (as of 2007). Average lifespan will be much lower, but I could not find reliably consistent figures.

Habitat: Overgrown fields and forest edge

Diet: Primarily seeds including thistle, sunflower, birch catkins, but will also eat insects during breeding season

When is it here? American goldfinches are found in New Hampshire all year round.

Where does it go in the winter? In the winter, American Goldfinches may move south to avoid severe cold, but the summer and winter ranges have considerable overlap according to National Geographic Field Guide to the Birds of North America, Sixth Edition. In places like New Hampshire where there is significant snowfall, American goldfinches often "hang out" close to backyard bird feeders with thistle seed or black-oil sunflower seeds during the winter months.

Life-cycle: According to information published by the USGS Patuxent Wildlife Research Center, American goldfinches lay 4-6 eggs per clutch once or twice per season. The eggs are very pale blue, almost white, and take 10-12 days to hatch and the baby birds are ready to leave the nest within 11-17 days after hatching. Breeding typically takes place in July.

Notes: The American Goldfinch makes a small, cup-shaped nest in the forking branches of trees and shrubs. Nests are often made of thistle or milkweed silk and other plant material woven tightly. Nests are usually constructed between 10-20 feet off the ground, but may be higher or lower. The Cornell Ornithology Lab reports that brown-headed cowbirds will often lay their eggs in the nests of American goldfinches, but that cowbird chicks cannot survive on the diet of regurgitated seeds and die within days of hatching.

What eats American Goldfinches? Many animals eat small birds. One of the biggest predators is the house cat. Others include bobcats, foxes, martens, fishers, raccoons, hawks like the sharp-shinned and Cooper's hawks, and many others.

IUCN Red List Status: Species of Least Concern, population trend: increasing

American Goldfinch Taxonomy:
The taxonomy of the American goldfinch is interesting because the genus was actually changed in the mid-1970's. Originally classified as belonging to the genus Spinus, it was reclassified into the genus Carduelis with Spinus becoming a sub-genus. It common to see the American Goldfinch listed either as Spinus tristis or Carduelis tristis.
Kingdom: Animalia (animals)
Phylum: Chordata
Class: Aves (Birds)
Order: Passeriformes (Perching birds)
Family: Fringillidae (True finches)
Genus: Carduelis (formerly Spinus)
Species: tristis

Tuesday, February 7, 2012

A Bull Moose (Alces alces): The Biggest, most Dangerous Animal in my Yard

Yearling Bull Moose (Alces alces) with spike antlers taken
in my backyard on February 6, 2012.
Photo by Brad Sylvester. Copyright 2012.
Sometimes I have to go to great lengths to find the animals that live in my yard, but when a bull moose (Alces alces) walks through the yard within 50 feet of the house, it's pretty hard to miss. This moose is definitely male, because it has antlers. Female moose do not grow them at all. Bull moose actually shed their antlers and regrow a new set each year.

The little spiky antlers on this moose tell me that it is almost certainly a yearling moose. Yearlings may keep their antlers later in the season than their more mature brethren who may drop their antlers around December. February or even March is not too unusual a date to see such a young moose still carrying last year's beginner antlers. You can tell that these are antlers from the prior season rather than newly developing antlers by the lack of velvet covering over them. In the pictures, the antlers of the moose that was in my yard appear hard and bony.

Moose Antler Growth

Bull moose showing developing antlers with brown velvet
feeding on aquatic plants in Errol, NH in July, 2011.
Photo by Brad Sylvester. Copyright 2011.
They would start out as buds around the end of April and begin growing with a brown, fuzzy covering called velvet. The velvet peels and gets scraped off on trees to relieve the itching as the antlers get ready for rutting season. The picture below shows a bull moose in July with his antlers coming in. The velvet shows clearly. You'll also notice that even though they are not nearly finished growing for the season, they are clearly going to be much, much fuller than those of the moose from my yard. This shows that the bull moose in the picture I took last summer in Errol, is older. You can see the full video of this adult male moose eating here. According to the New Hampshire Fish and Wildlife Service (NH F&G), the antlers of a mature moose may weigh 40 pounds.

Bear Killers

Even though it is still young, the yearling moose stands 6 feet tall at the shoulder and about eight feet tall overall. Moose are big animals. Already, this moose weighs more than a typical full grown black bear. During the fall mating season when it is full of hormonal aggression, it is also more dangerous than a black bear. The most dangerous moose, however, is the female with a young calf. They are fiercely protective and can not tolerate any creature physically getting between them and the calf. The NH F&G website claims that female moose have been known to kill not only people and black bears, but also the larger grizzly bear while defending their calves. These are very dangerous animals.

Although a female moose isn't as big as a male, an average adult moose weighs 1000 pounds and big bulls may go as high as 1500. The North Country News says that the largest female moose taken by hunters in New Hampshire was about 1100 pounds estimated live weight, while the largest bull taken in the Granite State would have tipped the scale at an estimated live weight of 1400 pounds.

Bull Moose trotting off down into the forest in my
backyard.
Photo by Brad Sylvester. Copyright 2012.
That makes the moose the biggest wild land animal not just in my yard, but in all of New Hampshire by a wide margin although cattle may weigh more. Despite its great size, moose are vegetarians eating leaves twigs and buds of trees during the winter and aquatic plants during the summer. Their noses close up to prevent water from getting in while they stick their heads underwater to graze.

There is a large marshy area in the valley below my house, perhaps a mile and a half away. This would be ideal summer grazing territory for moose while the forests make good winter habitat. Moose are excellent swimmers. Having watched one swim across a lake, I think I'd be pretty hard-pressed to out swim a moose for very long. On land, however, there's no question; the moose easily wins with a running speed that can top out around 35 miles per hour.

Moose Scat


Old moose scat from the woods at the back of our property
Photo by Brad Sylvester. Copyright 2011.
 About a month ago, I found moose scat down on the back part of my property, but it appeared to be at least a year old. Because it contains mostly woody material from the moose's winter diet, moss was actually growing on it. It looks a bit like compacted sawdust. Each pellet is about an inch long, much bigger than deer pellets. When we first moved here about 4-5 years ago, I saw a very young moose crossing the road about five miles away and we have seen moose tracks in the snow within a mile of our house, but this is the first time we've seen a moose on our property. Here's a video I took of a very young moose with its mother in Northern Maine.

The two depressions behind the print on the left are from
the dew claws of the hind foot of the moose.
Photo by Brad Sylvester. Copyright 2012.
After giving the moose in my yard a head start of about an hour, I followed its tracks through the woods in my backyard for over a mile onto a neighbor's property and into a protected wilderness area on the other side of that. I was curious to see where it went, but couldn't devote the entire day to following it; perhaps another time. I did find one hair from the moose's coat stuck on a tree branch that it pushed aside as it walked through the forest. You can see from the photo below that it is much thicker than a human hair placed next to it for comparison.

Moose tend to be solitary creatures. With the exception of mother and calf, and during the rutting season (mid-September to mid-October), they will most often, though not always, be spotted alone.

Moose hair on right,
human hair on left.
Photo by Brad Sylvester.
Copyright 2012.
Moose Tracks

Moose tracks are also big. They tend to have obvious dew claw marks in the snow, especially on the rear feet. The tracks from the moose in my yard measured six inches long without the dew claws, nine inches with them. They were 5.5 inches wide. Like deer prints, if the moose is running or trotting then the front part of the hoof will tend to be splayed open with more space in between the two halves.


The red arrows point to the dew claws at the back of
each hoof. The dew claws of the rear feet tend to show
up more prominently in the moose tracks.
Photo by Brad Sylvester. Copyright 2012.
 The stride of this moose varied from about three feet to about seven feet between prints depending upon the speed at which it was traveling. The rear prints tend to fall directly on or very near the front hooves, leaving a track pattern not unlike the one that a person would leave with left and right prints alternating.

Quick Facts about the Moose (Alces alces):

Diet: Moose eat twigs, leaves and buds from trees, especially during the winter. In the summer, they prefer grazing on aquatic plants pulled form the bottoms of shallow lakes, rivers and marshes.

Habitat: Forest and marshland.

When is it here? The moose lives in New Hampshire all year round, but may move from forest to marshland depending upon the season.

Home range: From 1-25 square miles according to NH F&G.

Where does the moose go during the winter? The moose will forage in the forest or at the forest edge during the winter. It is not bothered by cold, unless its coat is damaged or worn off by scratching (such as might be caused by a tick infestation).

Life Cycle: Moose mate from mid-September to mid-October. 1-2 calves will be born in late May or early June. The calves are cared for by their mother for about a year. Females are ready to mate during their first year while bulls take a few years to grow big and strong enough to challenge for the right to mate by clashing antlers with other rutting males.

Moose Lifespan: Moose typically live 10-15 years.

Moose taxonomy:
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Cervidae
Subfamily: Capreolinae
Genus: Alces
Species: Alces alces




Friday, February 3, 2012

To catch a deer mouse (Peromyscus maniculatus)

Notice the bicolored tail, dark above, white below, on the
deer mouse (Peromyscus maniculatus)
Photo by Brad Sylvester. Copyright 2012.
There are a number of different species and subspecies that are popularly called deer mouse, wood mouse, or white-footed mouse. Many have a similar appearance and if you just catch a glimpse of one or are just looking at a top view as it sits in a bucket waiting to be carried far away from the house, then it can be hard to tell the difference between them. This appears to be a deer mouse of the species Peromyscus maniculatus.
One of the best websites detailing the differences between the deer mouse and similar species is enature.com. The tail is one key point of identification. In Peromyscus maniculatus, the tail is dark above and light below. There’s a clear demarcation of the two colors on the tail which should be about the same length as the rest of the mouse. The bicolored tail is shown clearly in the photo at the top left of this post.

The white underbelly with the tail details, the color of the top of the mouse’s body, the large, bulging eyes, and the location where it was found (New Hampshire) make it a pretty sure bet that this is, in fact, Peromyscus maniculatus, even though there are four species of mice that are native to New Hampshire and one (the house mouse – Mus musculus) that was introduced from Europe and is now firmly established here and throughout North America . If you look up images of the species by the common name on the Internet, however, odds are about fifty-fifty that you’ll get something other than Peromyscus maniculatus.

Deer mice typically live in the forest and fields and do quite well without coming into human houses during the winter. They will burrow under the snow seeking seeds and other edible plant material. In my yard, they will eat the soft green bark of bushes and shrubs below the snow so the damage isn’t visible until the snow melts in the spring. Once the snow does melt, however, the gnaw marks are very clear often girdling the bush (removing the bark all the way around it), which kills the plant.
From the top, not enough distinguishing features can be seen
for a positive identification of the deer mouse (Peromyscus
maniculatus).
Photo by Brad Sylvester. Copyright 2012.

We do, however, get an occasional mouse inside the house when there is a period of particularly cold or severe winter weather. They come in seeking better shelter and a more ready source of food.
Mice are prolific breeders. Just a couple slipping into the house can turn into an infestation if not quickly eliminated. Once inside, they’ll also look for whatever foods they can find there: dog food, cat food, my food.

For that reason, and because the area in which we live has carpenter ants which would like nothing better than to chew up the structural wood of our house until it falls down around our ears, our house is serviced regularly by an exterminator. They bait for rodents in the crawl spaces and little nooks and crannies where they might be otherwise found. This is quite effective and we generally don’t have mice around, at least not for very long.

Outside, however, there are the tunnels in the snow that reveal their presence and favored routes. To catch one, I just needed to put this live capture mouse trap , baited with peanut butter, in the walkway near the opening to one of the snow tunnels.   That's what led to the photo opp. for this little guy. This deer mouse was released unharmed.

Quick Facts about the Deer Mouse (Peromyscus maniculatus):

Diet: The deer mouse eats seeds, insects, berries, nuts and mushrooms. The US Forestry Service doesn't list the green inner bark of shrubs as part of the deer mouse diet, but I have the dead ornamentals to prove it, although they don't seem to choose it when other food is available in the summer. Since they seem to only eat it when it is under the snow, it is hard to catch them in the act. In this case, however, the tunnels, footprints, and captured deer mouse itself provide pretty solid evidence that this is the species that is eating the bark. 

Range: According to US Forestry Service, the deer mouse lives pretty much all throughout the continental United States except the extreme southeast (northern Georgia yes, Florida no). It can also be found in parts of Mexico and Canada west to southeastern Alaska.

Habitat: Deer mice live in just about every type of habitat: forests, fields, scrub, canyons, desert, you name it. They build nests just about everywhere, too. Deer mouse nests can be found high in trees, in underground burrows, in scrub piles, rock piles, and all sorts of man-made structures (like houses, cars, and barbecue grills) where they can stuff leaves, grass and other soft insulation to make it more comfortable.

Reproduction: Litter sizes may range from one to nine, but three to five is more typical. Gestation lasts 22-26 days and females may have several litters each year. The US Forestry site says that as many as 14 litters in a single year have been reported. At about 48 days of age, female deer mice are sexually mature and ready to begin having litters of their own.

When is it here? The deer mouse is a year-round resident of New Hampshire.

Where does it go int he winter? The deer mouse does not hibernate and is fully active throughout the winter.

Territory:

Predators: What eats deer mice? Many New England animals eat deer mice. The owl, coyote, fox, bobcat, house cat, snakes, weasels, martens, fisher cats, mink, chickens, and even skunks will all eat deer mice either regularly or opportunistically. With so many predators, the deer mouse relies on frequent litters and rapid maturation to maintain its population.

Deer Mouse Taxonomy:

Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Cricetidae
Genus: Peromyscus
Species: Peromyscus maniculatus


Sourcing Note: Because the range of the deer mouse covers such a wide variety of climates and geography, there are variations in reports of diet, litter size, litter frequency and other aspects of behavior among different sources. They may all be correct for different regions, but I have used data from the US Forestry service website linked above for information that I have not directly observed myself.