Today we get the gift of time. Leap Day, February 29, gives us 24 hours that are usually missing from our calendars.
You probably know we have to insert this day every four years because the earth revolves around the sun in approximately 365.25 days. To make the calendar match the stars and seasons we add an extra day every fourth year with a complicated century exception. The 4-year-old video above explains the details of this astronomical problem and how Julius Caesar and Pope Gregory XIII figure into it.
Last June 30 we received the gift of an extra second. You probably missed it because it happened just before midnight.
Leap Second on June 30, 2015 (image from Wikimedia Commons)
Leap Years and Leap Seconds are unrelated but caused by a similar problem. Just as calendars must adjust for Earth’s rotation, so too must atomic clocks. The clocks are extremely accurate but Earth’s rotation is slowing down and not even at a consistent rate. An extra second is added whenever the difference between mean solar time (UT1) and Coordinated Universal Time (UTC) reaches 0.9 seconds. The need for this second is so unpredictable that it’s announced only six months in advance. Computers hate this but there are workarounds.
In the past eight months we’ve gained 24 hours (on February 29, 2016) + 1 second (on June 30, 2015) + 1 hour (changed to Standard Time on November 1, 2015). This nets us 25 hours + 1 second.
Do something fun with the gift of time. Happy Leap Day!
p.s. We’ll lose an hour in two weeks on Sunday March 13 when we switch to Daylight Savings Time. Yikes!
(Leap year video by Epipheo on YouTube. Leap second illustration from Wikimedia Commons; click on the image to see the original)
(*)The last Carolina parakeet (Conuropsis carolinensis) died in captivity in the Cincinnati Zoo on February 21, 1918. That’s also where the last passenger pigeon died three and a half years earlier on September 1, 1914.
Until last Thursday I thought these palms were hard to identify. On our visit to Merritt Island National Wildlife Refuge, Chuck Tague explained that if you look at the stem and arrangement of fronds it’s easy to tell the difference between these three Florida natives.
Scrub palmetto’s (Sabal etonia) fronds all grow from the tip of the stem in a palmate fan — the way your fingers branch out from your palm. It never stands up like a tree because its trunk usually remains underground. We saw a Florida scrub-jay perched on scrub palmetto at Scrub Ridge Trail.
Saw palmetto’s (Serenoa repens) fronds are also palmate but the stem is serrated, giving the “saw” in its name. This one doesn’t stand up either. Its trunk lies on the ground or just below the soil.
Sabal palm’s (Sabal palmetto) fronds are pinnate, sprouting on two sides of the stem instead of from the tip. These palms are upright and become trees up to 65 feet tall — the state trees of Florida and South Carolina.
Look closely at the fronds and stems and you can read the palms.
Anhinga with young in nest (photo by shell game via Flicker Creative Commons license)
Last Sunday at Wakodahatchee Wetlands I was pleased to see anhinga nestlings up close even though the small ones are rather ugly.
Anhingas (Anhingaanhinga) nest colonially in woody shrubs above water during south Florida’s dry season (November to May) because low water levels concentrate the fish and make them easier to catch.
Newly hatched anhingas are pale, naked and reptile-like though their eyes are open*. The females lay eggs up to four days apart and begin incubation immediately so the young in recently hatched nests range in size and appearance from small naked hatchlings to large downy first-born.
The nestlings beg with their mouths closed and their gular pouches extended (the skin beneath their beaks), asking their parents to dole out food by regurgitation.
Below, an older nestling has his head inside his mother’s mouth to get food from her gular pouch while the younger one on the left looks angular because he’s begging with extended gular skin. His throat looks bigger than the top of his head!
Anhinga feeding nestling while second nestling begs (photo by shell game via Flicker Creative Commons license)
Eventually the youngest catch up to the oldest … still with faces that only a mother (and father) could love.
Anhinga nestlings (photo by Jimmy Smith via Flickr Creative Commons license)
(photos by shell game and Jimmy Smith via Flickr, Creative Commons Atrribution Share-Alike Non-Commercial License)
Spot-breasted oriole (photo from Wikimedia Commons)
Here on the east coast of Florida I’m looking for a Life Bird. I’ve been to this part of the country so often that I’ve seen all the easy ones, but there’s a bird in Broward County that fits the bill.
Spot-breasted orioles (Icterus pectoralis) are native to Mexico and Central America but were introduced to the Miami area in the 1940’s. Since then they’ve raised families, spread out a bit and become so established that they’re “count-able” according to American Birding Association rules. I found out they’re at Markham Park in Broward County where I heard that a western spindalis was hanging out with them in January.
The western spindalis is gone (alas! not reported since January 31) but the spot-breasted orioles are still there so I’m going to seek them out.
If I see one, I can count him.
(*) “Countable”: When a new species is introduced to North America it can’t be counted as a wild bird on ABA Life Lists until the ABA determines that it’s become established on its own. Of course I have my own list of exceptions that count for me but aren’t official. Click here for the ABA rules and here for the ABA checklist.
(photo from Wikimedia Commons. Click on the image to see the original)
p.s. Alas! Bad luck. I didn’t find the spot-breasted orioles even though two were seen on Sunday.
Since I come from a landlocked place (Pittsburgh) I don’t pay attention to tides but I’d better take note this week if I want to see shorebirds.
The tide where I’m visiting the east coast of Florida has a high-to-low difference of 2 to 3 feet depending on the harbor. This doesn’t look like much but it makes a difference to birds. They can take their time in Florida as the water rises slowly.
Birds have to act fast at the Bay of Fundy where the tides are the highest in the world. With a range of 40-55 feet docks look absurd at low tide and mud flats are inundated quickly. The time-lapse video below shows tidal rise and fall at Hall’s Harbour, Nova Scotia. The birds show up for a relatively brief moment at low tide.
On the opposite side of the Atlantic there are locations in the U.K. with impressive tides, too. Click here for illustrations, then click on each photo of low tide to get the same scene at high tide.