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Gardening For Wildlife #42, About Dark Eyed Juncos
November 12, 2007
Welcome new readers.
The weather this past week in Michigan has been close to normal for this time of year. Cooler, gray clouds, (dad called them snow clouds) some rain and a few snow flakes.
Northern Michigan received its first few inches and parts of the upper peninsula received more than a foot of the white stuff.
The Sunsets are now well before 5:30 PM, that means my walks with Keet are in the dark.
Most of the yard work is done. If I can't get at the rest, it will hold over till spring.
Remember to leave some leaf litter.
Leaf litter helps to insulate plants.
Leaf litter is a vital place for certain insects to hibernate.
Insects, larvae and insect eggs that offer a vital food source for many birds during the winter and early spring.
Don't cut back your ornamental grasses.
Besides offering a waving contrast in our winter yards, the grass clumps offer important protection for birds from predators and winters wrath.
Several Canada geese and Mallard ducks congregate at the pond during the day. Many of them roam the neighborhood looking for goodies (I feed the ducks).
Karen is now in the act of trying to hand feed our special red breasted nuthatch, he is so tame.
Have you enjoyed fall migration so far?
With shorter days and cooler nights the feeders are busy most of the day.
Steve from North Carolina let me know how one day last week there were several new visitors to his yard. Juncos, white crowned sparrows and others seemed to appear just like that.
That is one of the blessings of migration and sometimes they stay.
Birds remember where the groceries are from one year to the next and will return if you keep them supplied.
Juncos are a backyard favorite this time of year.
Often called snowbirds because most of us in the lower 48 states only see them during fall and winter.
Cornell's feeder watch records more than 80% of reports showing juncos. More than any other species of bird.
Experts figure Juncos to number some where around 280 million strong. Second in North American bird population only to the American robin (figures guessed over 300 million).
You guessed it, todays main topic is on the Dark-eyed-Junco.
Dark-eyed-Juncos (Junco hyemalis)
Juncos are a widespread and common small sparrow, the Dark-eyed Junco is most familiar as a winter visitor to bird feeders.
It comes in several distinctly different looking forms, but all are readily identified as "Juncos" by their plain patterning, dark hood, and white outer tail feathers.
Juncos are the "snowbirds" of the middle latitudes.
In the eastern United States, they appear in all but the most northern states only in the winter, and then retreat each spring.
Some juncos in the Appalachian Mountains remain there all year round, breeding at the higher elevations. These residents have shorter wings than the migrants that join them each winter. Longer wings help the migrants fly long distances.
The Dark-eyed-Junco includes five forms that were once considered separate species.
The Slate-colored Junco is the grayest, found from Alaska to Texas and eastward. Yes, even in my Michigan.
The Oregon Junco is boldly marked blackish and brown, with a distinct dark hood, and is found in the western half of the continent.
The Gray-headed Junco has a brown back and gray sides and lives in the central Rocky Mountains.
The White-winged Junco is all gray with white wingbars, and breeds only near the Black Hills of South Dakota.
The Guadalupe Junco of Baja California is dull and brownish.
Two other forms may be distinguishable:
The Pink-sided Junco, a pale version of the Oregon junco, living in the northern Rocky Mountains.
The Red-backed Junco, a gray-headed junco with a dark upper bill, found in mountains near the Mexican border.
Beeding grounds are Alaska, Most of Canada, the extreme northern state,down the mountains to California and Northern Georgia.
Juncos winter from southern Canada to Northern Mexico.
Now that is a huge range.
Juncos spend the entire winter in flocks averaging in size from six to thirty or more birds.
Each flock has a dominance hierarchy with mature males at the top, then juvenile males, mature females and young females at the bottom.
You can often observe individuals challenging the status of others with aggressive displays of lunges and tail flicking.
I've mentioned before how birds often have a hierarchy, now is your chance to observe and find the boss of your backyard.
Males remain further North so they can take advantage of prime breeding grounds. Juvenile males remain further North.
Males will return to the same breeding ground year after year.
With nests are on the ground, rodents such as Chipmunks and Deer mice are major predators on the eggs of Juncos.
The longevity records for Juncos are: White-winged - 7.5 years; Dark-eyed -10 years, 9 months; Oregon - 9 years, 9 months; Gray-headed 10 years, 8 months.
About 70% of the Juncos in the South are females as they know how to take advantage of favorable conditions.
Like most sparrows, Juncos are ground feeders. You will often see them hopping back and forth or scratching for food.
Backyard feeding favorites are millits and cracked corn. On an annual basis, a Junco's diet is made up of approximately three parts seeds to one part insects.
During the nesting period, the percent of insects can increase up to 50 or 60 percent of their diet.
Sometimes you will see them riding a seed stalk to the ground and then feeding.
Kinda makes you want to keep a few weeds around.
A Few Tidbits:
Juncos have over 30 percent more feathers (by weight) in the winter than they do in summer.
Juncos prefer to roost in evergreens at night, but will also use tall grasses and brush piles.
They return to the same roost location repeatedly and will share it with other flock mates, but they do not huddle together.
Nests are built on the ground using rootlets, dried leaves, moss and lined with fine grass.
Because nests are on the ground, chipmunks, kangaroo mice and other rodents are main predators of eggs and new hatchlings.
An average clutch is 3 to 5 eggs and she may have as many as 2 clutches a season.
Eggs incubate in 11 to 13 days and young fledge on average, 12 to 14 days.
One last thing on Juncos
Yes there have been studies.
Indiana University Bloomington, University of Virginia and University of Southern Mississippi researchers report the results of the first study to examine, in the wild, the way in which natural changes in testosterone levels determine how a male spends his time.
IUB biologist Ellen Ketterson and other researchers had thought it might be the total amount of testosterone in a male bird that determines his tendency toward aggression and monogamy.
The latest findings suggest it's a bit more complicated. It's how much and how quickly his testosterone levels can rise and fall that determines whether he's the kind to stick around and feed his young.
Males whose testosterone levels were more stable were more likely to invest more time and energy in parenting.
"This study is one of the first to show for a songbird living in the field under natural conditions that individual variation in the hormone testosterone maps onto variation in aggression and parental behavior," said Ketterson, senior author of the study.
The data also suggests that there is more than one way to be successful at reproduction.
Some males may seek mates at the expense of parental behavior, but other males are doing the opposite.
They are being more parental at the expense of aggression. And apparently both ways of being in the world work.
Males have a certain amount of energy and time they can invest in attracting mates and sticking around to parent offspring.
Under certain circumstances it may be beneficial for male birds to love 'em and leave 'em, maximizing the number of female partners during a mating season.
Under other circumstances, it may be in the male Junco's best interests to mate with only one female and stick around until the chick is old enough to fend for itself.
The conclusion of the study suggests its the amount of testosterone that determines if the male stays to help or not.
Habitats may play a roll in this and either way. it seems to work for Dark-eyed-Juncos.
All 280 million of them.
Are your birdbaths ready for winter?
Are feeders cleaned and filled?
Remember, days are shorter that means less time to get the energy required to survive longer cooler nights.
Read up on bird feed,
Go to feeding birds
These two are favorites of Dark-eyed-Juncos.
You will get some nutritional facts and some history.
I like to toss some under my shrubs this time of year.
It's time to fly for now.
"Nature" is Grand!
Makes you want to smile.
It puts a big smile on my face.
Besides creating nature to share, God created smiles to share too.
A shared smile can make someone's day and helps you feel better as well.
Go ahead, share a big pretty smile with someone today.
Until next time...........
"Treat the earth well:
It was not given to you by your parents,
It was loaned to you by your children.
We do not inherit the Earth from our
Ancestors, we borrow it from our Children."
Ancient Indian Proverb
Your friend indeed,
PS: Feel free to forward this to friends and family or send them to www.gardening-for-wildlife.com so they can register to recieve their free copies.
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