Category Archives: Phenology

Watch for Witch Hazel

Witch hazel flowers catch the light after the leaves are gone, November (photo by Kate St. John)

When the leaves are gone these lacy flowers stand out in the forest.

American witch hazel (Hamamelis virginiana) blooms from late October into December in eastern North America.  Its delicate yellow flowers smell like lemon.

Witch hazel flower, October in Schenley Park (photo by Kate St. John)

Since witch hazel blooms when few insects are out how are the flowers pollinated?

In 1987 Bernd Heinrich found that owlet moths come out at night to sip the flowers and thereby pollinate them.

The moths survive cold weather by hiding under leaf litter during the day, then shivering to warm up and fly at night. Click here to learn more.

(photos by Kate St. John)

When Will Most Of The Trees Be Bare?

Leafless bur oak, Schenley Park, 4 Nov 2011 (photo by Kate St. John)

Every year I record the date when most of the trees are bare on my favorite hillside in Schenley Park — the hill at the end of the Greenfield Bridge.

In 2008 the leaves were gone by 2 November.  In 2012 Hurricane Sandy stripped them from the trees by 4 November.

Last year the changes happened much later. In 2017, the leaves were still green in late October and more than half were still on the trees on 27 November.  Here’s a 2017 slideshow of autumn trees on that hillside.

  • 26 October 2017: Lots of green at the end of October 2017.

This year is similar to last so I wonder … When will most of the trees be bare?  November 15?  20?  30? Later?

Let me know how the trees look where you live and vote for the date “When Most of the Trees Will Be Bare” by leaving a comment below.

HINT!  Two factors that affect leaf loss on this hillside:  (1) More than half of the trees are oaks; oaks drop their leaves later than maples.  (2) This city location is warmer than surrounding counties.

(photo by Kate St. John)

Gentian Gone To Seed

Bottle or closed gentian (Gentiana andrewsii) blooms in September in western Pennsylvania.  By the end of October it’s gone to seed.

In bloom this gentian’s tightly closed petals prevent most insects from reaching its nectar, though bumblebees can force their way in. 

Bottle gentian in bloom, September 2015 (photo by Kate St. John)

Carpenter bees take a shortcut. They drill a hole in the petals to access the pollen and nectar. Once there’s a hole, honeybees and other small insects use it, too.

When I found the faded gentian shown above, I plucked a dried flower to examine the seeds.  Aha!  The closed petals have two holes in them.  The seed pod also has two curled knobs at the top.

I pulled the knobs apart to reveal the seeds …

… and scattered them nearby. 

I hope they’ll become new gentians next year.

(photos by Kate St. John)

House Sparrows Put On Their Winter Coats

House sparrow in British Columbia, Canada (photo from Wikimedia Commons)

Birds that eat insects leave Pennsylvania for the winter but the omnivores, like this house sparrow, stay behind.  Food won’t be a problem but it’s going to get cold so the house sparrows get ready in advance.

A study by Lowther and Cink in 1992 found that house sparrows (Passer domesticus) prepare for winter by molting into heavier plumage. Plumage weight increased 70% between August and September alone.  Summer weight is 0.9 grams; winter weight is 1.5 grams.

In September the house sparrows put on their winter coats.

(photo from Wikimedia Commons; click on the caption to see the original. 
This article was inspired by page 153 of Ornithology by Frank B. Gill, 3rd edition.) )

Fall Foliage: When?

Moraine State Park, 15 Oct 2017 (photo by Kate St. John)

Summer ended on Friday morning. Brrrr! Now that it’s cold, it’s time for colorful fall foliage, right?

Some reports say western Pennsylvania won’t have pretty leaves this fall, others say we will.  One thing is certain, though. The leaves stayed green longer than usual.

Twenty years ago our fall foliage reached its peak around October 15 but today — only one day before the 15th — the leaves have just begun to change.  We had the same situation last year as shown in my photo taken at Moraine State Park on 15 October 2017.

Delayed timing makes it hard to know when fall color will reach its peak but the Pennsylvania Bureau of Forestry (DCNR) is here to help.  Check out their Fall Foliage Guide complete with an interactive map and weekly reports.  The October 11-17, 2018 forecast map is shown below (yellow means “approaching best color”). Click here or on the caption to see the full report.

screenshot of Pennsylvania Fall Foliage Report, Oct 11-17 2018, by PA DCNR

Don’t worry if you haven’t gone “leaf peeping” yet in western Pennsylvania.  You still have time to see fall colors this month.

(photo by Kate St. John, Screenshot from the Pennsylvania Fall Foliage Report, October 11-18, 2018, PA DCNR; click on the caption to see the original)

Questions To Answer This Fall

Woolly bear: Isabella Tiger Moth caterpillar (photo by Kate St. John)

It’s early October and the woolly bear caterpillars are back, right on time. But one thing is very odd. The weather is quite hot.

The temperature outlook map shows what we already know: There’s a 70% chance October 2018 will be warmer than normal in Pittsburgh. Highs will be in the 80s today through Wednesday (Oct 7-10)

Temperature Outlook for October 2018 as of 9/30/2018 (map from NOAA climate.gov)

How is this affecting the plants and animals we usually see in October?

In a normal October 20 years ago, fall foliage color would peak in Pittsburgh by the middle of October, sparrows and ducks would migrate through our area, and the average first frost would occur around October 15.  Will those things happen on time this year? 

ISeeChange.org is interested in the answer. They’re wondering: “What do you usually expect at this time of year? What does it look like outdoors, sound like, smell like, feel like?  Are your expectations met, or are things different?  Are there trends in your community that we need to be paying attention to?”  

Click here for a list of what we ought to expect in October in southwestern Pennsylvania. 

Record what you find at ISeeChange.org:

(photo of woolly bear by Kate St. John, map from climate.gov; click on the caption to see the original)

Flowers in a Purple Theme

Scaly blazing star, July 2018 (photo by Dianne Machesney)
Scaly blazing star, July 2018 (photo by Dianne Machesney)

Yellow flowers are abundant in the summer while some of the rarest flowers are purple. Here are four rare plants I’ve never seen.

Dianne Machesney visited Lynx Prairie in Adams County, Ohio in late July to see scaly blazing star (Liatris squarrosa), above. It doesn’t occur in Pennsylvania though we have it’s cousin dense blazing star (Liatris spicata) at Jennings Prairie.  The two plants differ in this way: “Scaly” flowers are clustered at the tip, “dense” flowers coat the long spike.

Lynx Prairie is also famous for these rarities shown left-to-right below: American bluehearts (Buchnera americana), crane fly orchid (Tipularia discolor) and crested coralroot (Hexalectris spicata).

Lynx Prairie in Shawnee State Forest is a great place to find rare flowers in a purple theme.

(photos by Dianne Machesney)

Turning Green

Male scarlet tanager in August 2015 (photo by Tim Lenz via Flickr, Creative Commons license)
Male scarlet tanager on an ash tree, August 2015, Chemung County, NY (photo by Tim Lenz via Flickr, Creative Commons license)

Yesterday in Schenley Park I saw a scarlet tanager with blotches on his belly.  He was starting to turn green.

Scarlet tanagers (Piranga olivacea) molt twice a year.  In January through March they molt into breeding or “alternate” plumage while on their wintering grounds in South America. The females don’t change color but the males turn from green to scarlet. Young males often retain a bit of green (click here to see).

When the breeding season is over, they molt back to basic plumage in July through September. The males look blotchy at first but when they’re done they’re bright olive green with black wings as shown below.  By then they’re on their way to South America.
(photo at top in August, Tim Lenz; photo below in Oct, Andy Reago & Chrissy McClarren)

Scarlet tanager in October 2015 (photo by Andy Reago & Chrissy McClarren via Flickr, Creative Commons license)
Scarlet tanager in October 2015 (photo by Andy Reago & Chrissy McClarren via Flickr, Creative Commons license)

I was lucky to see yesterday’s scarlet tanager because he hardly made a sound.  Tanagers have stopped singing now that breeding is over.  This one was singing very softly.

 

p.s.  Did you know that female scarlet tanagers sing?  According to All About Birds: “The female Scarlet Tanager sings a song similar to the male’s, but softer, shorter, and less harsh. She sings in answer to the male’s song and while she is gathering nesting material.”

(photo credits: scarlet tanager turning green by Tim Lenz via Flickr, Creative Commons license; yellow-green scarlet tanager by Andy Reago & Chrissy McClarren via Flickr, Creative Commons license)