How Deer Create a Browse Line

Deer, Schenley Park
Browse line in Schenley Park — gap below the trees — at the entrance to the Upper Trail, 18 August 2023 (photo by Kate St. John)

23 August 2023

The white-tailed deer population in the City of Pittsburgh has been so high for so long that most people think the browse line in our parks is normal, but the light-gap you see under the trees above is not normal in a balanced forest. It’s a sign of deer overpopulation. Here’s what a browse line is and how deer maintain it.

Browse line: A phenomenon that occurs when herbivores consume all of the vegetation in the woods between the ground and the level of their highest reach. A clearly visible line is formed between the leafed and the leafless areas.

— paraphrased from Blue Jay Barrens: Fallen Trees and Browse lines, May 2011

Is the browse line hard to recognize in the photo above? Here’s an extreme example.

Tuileries Garden in Paris, a man-made browse line (photo from Wikimedia Commons)

This eye-level view of the Grande Allée of horse chestnut trees at the Tuileries in Paris is a man-made browse line in which gardeners trim the trees and clear the ground to maintain an opening beneath the trees at uniform height. Nothing is growing between the ground and the trimmed height.

An individual deer browsing the ground and lower branches of trees does not create the browse line. It’s the cumulative effect of too many deer eating at the same location over and over.

Last Friday I watched two 8-point bucks, antlers in velvet, maintain the browse line next to the Upper Trail at Schenley Park. The current browse line, seen in the video, is that clear view straight through the woods to the cars passing on the road beyond.

In the video the bucks eat herbaceous stems and leaves on the ground, then switch to twigs, leaves and stems of trees. About halfway in, the buck on the right stands on his hind legs to reach the lowest branches. The buck on the left wrestles with a tree to yank off the branches. Deer only have lower teeth so they can’t sharply bite off a branch like a beaver would.

Two bucks reinforce the browse line in Schenley Park, 18 Aug 2023 (video by Kate St. John, taken with my cellphone. These deer are close!)

In late August, when forage should be quite plentiful, these bucks are forced to eat their own cover and what little remains of the edible plants.

Buck in velvet has no cover to hide him, Schenley Park, Aug 2022 (photo by Kate St. John)

p.s. Here’s what the forest would look like if there was no browse line.

No browse line here, August 2023 (photo by Kate St. John)

(photos by Kate St. John, taken with my cellphone)

Never Use Sticky Tape for Lanternflies! It Kills Birds!

Bird Behavior, Insects, Spotted Lanternflies
embedded photo from Audubon News: Downy Woodpecker found in Brooklyn. Photo: Sarah Valeri

22 August 2023

Invasive spotted lanternflies are swarming over Pittsburgh right now, especially near the railroad tracks. Everyone wants to kill them but the first solution that comes up on any Google search is a very, very bad one. NEVER EVER use sticky tape to capture insects. Glue tape kills birds!

Audubon News, the source of the embedded photo above, wrote about the hazards of glue tape last March: Meant to Catch Spotted Lanternflies, Glue Traps Are a Horrifying Hazard for Birds. Only 10% of the trapped birds survive, even if they’re taken to a rehabber.

Raven Ridge Wildlife Center in Lancaster County, PA has years of experience with the harm caused by glue tape. This Facebook report from 17 August 2023 is just one of them. Three of the four trapped woodpeckers died and the fourth is in trouble.

So what can you do to kill lanternflies?

For trees use the Circle Trap. You can make it yourself. Instructions found here.

For home, make a simple vinegar trap :

Spotted lanternfly and insect vinegar trap (photo by John English)

Straight white vinegar plus dish liquid — maybe a 1/2 tsp — to break the surface tension. (Insect by-catch in this photo: a cicada.) Thanks to John English for this suggestion.

For personal combat there are lots of solutions: Electric “Tennis Racket” bug zappers, the Bug a Salt Gun, etc. found via Amazon searches.

Electric “tennis racket” bug zappers via Amazon search
The Bug a Salt gun via Amazon search

Watch a champion spotted lanternfly killer use these tools in a video from VICENews:

video from VICENews on YouTube

p.s. Why are spotted lanternflies more prevalent near railroad tracks? They arrived as egg masses stuck to railcars and hatched from there. Their host tree is the Ailanthus, an invasive weed that grows along the rail lines. They were first found in southwestern PA at a rail yard in Beaver County in 2020.

(photo and video credits are in the captions)

Schenley Park Outing: August 27, 8:30am

Books & Events, Schenley Park
Wingstem, Schenley Park, August 2022 (photo by Kate St. John)

21 August 2023

Late summer flowers are blooming, bugs are buzzing, and the migrating birds are on the move.

Join me for a bird and nature walk in Schenley Park next Sunday, August 27, 8:30am to 10:30am. Meet at the Schenley Park Cafe and Visitor Center where Panther Hollow Road joins Schenley Drive.

In addition to birds and flowers, this walk it will take a look at two huge effects humans have had on the landscape, both direct and indirect. Heavy equipment and deer.

Dress for the weather — including sun hat + water — and wear comfortable walking shoes. Bring binoculars and field guides if you have them.

Before you come, visit the Events page in case of changes or cancellations. The outing will be canceled if there’s lightning.

Hope to see you there!

(photo by Kate St. John)

Shades of Yellow and a Purple Host

Insects, Phenology, Plants & Fungi
Common sunflower closeup, 14 Aug 2023 (photo by Kate St. John)

20 August 2023

Someone in my neighborhood planted common sunflower (Helianthus annuus) on the strip of land between the sidewalk and the street. This month it droops over the sidewalk, so tall that I barely have to duck to take this closeup of yellow with a golden cast. Did you know this food plant is native to the Americas?

This woodland sunflower (Helianthus divaricatus), in a sunnier shade of yellow, was identified on the Botanical Society walk last Sunday at the Nine Mile Run Trail. The side of the flower is displayed because the bracts on the back and the bud are important. Click on the image to see a front view of the flower.

Woodland sunflower, Nine Mile Run Trail, 14 Aug 2023 (photo by Kate St. John)

This very yellow “pale jewelweed” (Impatiens pallida) is a rarity in Schenley Park. Deer have eaten all the other jewelweed yet this patch thrives. Why? The clue is in middle of this ugly photo.

Do you see the prickly branch of wineberry draped over the jewelweed plant? The entire patch is protected by this invasive thorny plant. The deer cannot approach. (Wineberry stems are circled in purple below.)

Wineberry (circled) drapes over yellow jewelweed in Schenley Park, protecting it from deer, Aug 2023 (photo by Kate St. John)

And a Purple Host:

I don’t remember the exact species of tick trefoil seen on the Botanical Society walk but a butterfly confirmed the plant is thriving.

Tick trefoil is the host plant for the silver spotted skipper. This one was sipping on an wet abandoned shirt nearby its host.

Silver spotted skipper sipping on a wet cloth, NMR Trail, 14 Aug 2023 (photo by Kate St. John)

(photos by Kate St. John)

Massive Migration

Migration
White stork flock migrating over Israel, Sept 2007 (photo from Wikimedia Commons)

19 August 2023

Fall migration is underway across the Northern Hemisphere. Some birds migrate alone or in small flocks that don’t attract much attention. Others gather in such massive flocks that they are hard to miss.

At pinch points along their migration routes from Europe to Africa, white storks (Ciconia ciconia) travel in very large flocks like the kettles of broad-winged hawks in North America. Two such pinch points are in the airspace over Israel, above, and at the Strait of Gibraltar.

In this short video white storks are about to cross the Straits from Spain to Morocco but hit a wall in the air — the levant wind blowing from the east — so they wheel back. They did not leave Spain that day.

In North America semipalmated sandpipers (Calidris pusilla) migrate in massive numbers from their breeding grounds in the Arctic to the shores of South America.

Semi-palmated sandpipers on migration in Maine (photo from Wikimedia Commons)

At the Bay of Fundy the flocks can number in the hundreds of thousands in August and early September.

(photos from Wikimedia Commons; tweets embedded)

Heat Changes Their Tune And Their Ears

Insects
Snowy tree cricket (photo by Andrey Zharkikh via Flickr Creative Commons license)

18 August 2023

On summer nights male crickets chirp to attract a mate. Each species has a distinctive call meant to lure the proper females. If you know bug sounds you can identify the chirping species.

One of the most common is the snowy tree cricket (Oecanthus fultoni) which occurs in most of the U.S. Unless you live outside their range you’ve probably heard this nighttime sound.

video embedded from Laura Symes on YouTube

Because they are ectotherms, crickets chirp faster in heat and slower in cool weather. You can even use Dolbear’s law(*) to calculate the ambient temperature based on the snowy tree crickets’ chirp rate.

So the sound changes. But does this heat-related change in tune mean the females no longer recognize the males? Nope. The heat changes the sound and it changes the crickets’ ears so that they hear the same old tune. Read more in this vintage article:

Tree Crickets Tune Their Ears

(*) p.s. The name of Dolbear’s law has an interesting backstory.
Amos Dolbear published The Cricket as a Thermometer in 1897 in which he described how to calculate the temperature based on the snowy tree crickets’ chirp rate. However, according to Wikipedia, Margarette W Brooks had already published the formula in 1881. She did not get the fame and it took some sleuthing to discover her. He got the fame and the name because, at the time, Science listened only to men. 140 years later women have a greater voice but the playing field is still uneven.

(photo and video credits are in the captions)

A Limpkin Irruption?

Migration, Water and Shore
Limpkin at Moraine State Park, 16 July 2023 (photo by Steve Gosser)

17 August 2023

After a limpkin was discovered yesterday afternoon in a small cove at Moraine State Park (first ever in Butler County!) western PA’s birding world spun on its axis and quickly went to find it. Many saw the bird yesterday including Steve Gosser who shared his photo above.

Limpkins (Aramus guarauna) are very, very rare this far north. Primarily from South America, these mussel and snail-eating wading birds have extended their range only to Florida where they live year round.

Limpkin range map from Wikimedia Commons

So what is a limpkin doing here? And not just “here.” A limpkin showed up at Middle Creek Wildlife Management Area last month and was still there last weekend. Two limpkins were in opposite corners of Ohio.

In fact, limpkins have been doing this crazy Northern Summer Visit thing for a long time but it appears they’ve ramped up since 2016. On 8 July 2023 Tim Healy posted a map of Limpkin Firsts in North America at the ABA Rare Bird Alert on Facebook. (The color descriptors are for the map.)
“Hot Limpkin Summer forever! Keep it going! Who’s next?
Green: home base
Blue: historical first records
Orange: 2016-2022 first records
Red: 2023 first records”

ABA Rare Bird Alert on Facebook: 8 July 2023, Tim Healy

This eBird map shows where they’ve been in 2023 up until 16 August. (I’ve marked the Butler County sighting as a red asterisk.)

eBird map of limpkin sightings in 2023 up until 16 August 2023

Is this an irruption of limpkins similar to the winter irruption of snowy owls? Maybe…

Young night-herons often do an out-of-range dispersal at the end of the breeding season when first-year birds explore to the north, then head home or die during their adventure. Perhaps limpkins are doing it, too. Perhaps they’ve had so much breeding success that there are extra limpkins to try it. (This family of 5 was photographed in Florida in 2014.)

Adult limpkin with 4 young, Winter Haven, Florida, 2014 (photo from Wikimedia Commons)

It will take some research to know the answer. The limpkins aren’t saying.

(photos by Steve Gosser and from Wikimedia Commons, maps from Wikimedia and eBird)

Where Is This Mosaic?

Musings & News, Trees
Beautiful mosaic. Where is it? (photo from Wikimedia Commons)

16 August 2023

Beautifully colored tiles. An intricate pattern. What floor, wall or ceiling holds this mosaic? Click here to see a closeup.

The photo caption at Wikimedia Commons has the answer:

Woody Dicot Stem Vascular Cylinder in One Year Liriodendron, photo from Berkshire Community College Bioscience Image Library, Pittsfield, Massachusetts.

The mosaic is made of cells in the woody stem of a one year old tuliptree (Liriodendron tulipifera), sliced thin and magnified 100 times. The colors and shapes are specific to the species and its age. The description indicates that things change at lot in a one year old tulip tree.

The mosaic slice was photographed in 2014 at Berkshire Community College in Pittsfield, MA from a sapling that probably grew in Western Massachusetts.

When a tulip tree grows up it has leaves and flowers like this.

Tulip tree leafout, Schenley Park, 28 April 2014 (photo by Kate St. John)
Tulip tree flower, 4 May 2017 (photo by Kate St. John)

Still beautiful and intricate even when not magnified.

For more information on the mosaic image see the description of the image here. It is so technical that I need a glossary to figure out what it means.

(photos from Wikimedia Commons and Kate St. John)

Baby Doves Get Taken For A Ride

Doves & Chickens, Nesting & Courtship
Juvenile mourning dove on a fence, 2008 (photo from Wikimedia Commons)

15 August 2023

Last Sunday while Bob Donnan was at the Pirates’ game, two young birds nestled in the windshield wiper well of his car.

Yesterday [13 August] when our Chevy Bolt was parked at the South Hills Village – Public Rapid Transit garage, two young [Mourning] Doves nestled into the lower windshield area. We didn’t even notice them until exiting the garage into brighter light! 

The car is so quiet that their short ride didn’t alarm them. After I stopped the car and waited for all traffic to pass, I waved my hand toward them and they flew off, back toward the parking garage.

— email from Bob Donnan, 14 August 2023
Immature mourning doves are surprised to take a ride (video by Bob Donnan)

I could tell by the birds’ appearance that they are juvenile mourning doves because they look spotty rather than smooth. Juvenile body feathers are so new that each one has a pale tip, giving the bird a scalloped look. Compare the top photo of a juvenile with this one of an adult.

Mourning dove adult (photo from Wikimedia Commons)

Why did the two birds hang out together?

Mourning doves (Zenaida macroura) nest multiple times per season and at each nesting the female lays two eggs that hatch in 14 days and fledge 12-15 days later. Just before they fledge the father completely takes over feeding duty so his mate can cycle and lay a new clutch.

The siblings are dependent on their father for 12-15 days after they fledge (26-30 days old). During this period they stay together in the same area during the day, never straying far, waiting for dad to show up. In the nest they learned to associate his voice with a feeding so if he calls they come.

Interestingly they have good homing skills even at this young age. If juveniles are forced from their “reference area” before they are 21 days old — i.e. while still dependent on their father — they always return within 24 hours.

Why at the parking garage?

Mourning doves nest in trees, shrubs and even on the ground but they have no problem nesting near humans and, according to Birds of the World, “may use unusual human-made substrates for nest sites, e.g. rain spouts, mops hanging on walls, immobile car accessories.”

Hmmm. “Immobile car accessories.” These two are probably not the only baby doves who’ve been taken for a ride.

(photos from Wikimedia Commons, video by Bob Donnan)

Migration! Arrivals & Departures This Week

Migration
Ruby-throated hummingbird, Annandale, NJ, 5 Sept 2012 (photo by Ellen & Tony via Flickr Creative Commons license)

14 August 2023

A lot of us think that fall migration doesn’t start until the end of August, but guess what? BirdCast resumed migration predictions on 1 August and their regional lists of Species On The Move show an influx of 10 noticeable species this week while five have already left, or are about to. Don’t wait to go birding. Check BirdCast tools to find out why.

Species On The Move uses two decades of eBird data to calculate movement from start to finish within four regions: Upper Midwest & Northeast, Gulf Coast & Southeast, Great Plains, and West. Of course they list First Arrival, Peak, and Last Departure but my favorite markers are:

  • Noticeability: *** Three asterisks mean we’re really likely to notice this species.
  • Rapid Migrant Influx: A few may be here already but numbers increase rapidly on this date.
  • Rapid Departure: Numbers drop quickly on this date though a few will linger.

The tables are grouped by region with Pittsburgh in the heart of BirdCast’s Upper Midwest & Northeast region. These dates are estimates but they’re good ones. Let’s take a look at who left and who’s coming soon.

Noticable Departures: Who Just Left?

Orchard oriole singing at Frick Park, 26 April 2023 (photo by Charity Kheshgi)

Have you noticed that orchard orioles, northern rough-winged swallows and willow flycatchers are basically gone? They started leaving in July, then rapidly departed in the first week of August. Yellow warblers and purple martins are not far behind. They’ll leave this week.

The screenshot below is a quick summary of rapid departures as of 13 August 2023. It shows:

  • Upper Midwest and Northeast region
  • Pared down to Noticeable birds (*** or **)
  • Sorted by Rapid Migrant Departure date
  • Not including some goodies such as Louisiana waterthrush, alder flycatcher and least bittern. (They’re on the website but not “Noticeable” for my pared-down screenshot.)
pared-down screenshot of BirdCast Species On The Move, noticeable Last Departures, Upper Midwest & Northeast

Noticeable Arrivals: What Rapid Influx will we see this week?

Immature ruby-throated hummingbird (photo from Wikimedia Commons)

If you haven’t seen them already ruby-throated hummingbirds will make a rapid influx today, 14 August.

The larger region will see increased numbers of common nighthawks and Canada Warblers but in Pittsburgh it’s usually the last week of August.

Common nighthawk photo by Chuck Tague; Canada warbler photo by Kuldeep Singh

Here’s a quick summary of Beginning Arrivals as of 13 August 2023 — same parameters as the departures above.

pared-down screenshot of BirdCast Species On The Move, noticeable Beginning Arrivals, Upper Midwest & Northeast

The tables change every day, dropping past dates and picking up new species in the future, so check out BirdCast’s Species on the Move to find out what’s happening near you.

p.s. How will you know if it’s worth going birding? Check BirdCast Migration Tools for forecast maps, live maps and alerts.

(photos from Wikimedia Commons, Charity Kheshgi, Chuck Tague, Kuldeep Singh. Tables are modified screenshots from BirdCast’s Species On The Move for the Upper Midwest and Northeast. Be sure to check BirdCast for the latest data)