This week’s big news was the unexpected prothonotary warbler that Charity Kheshgi and I found in Frick Park on 25 May. He was still present yesterday but BirdCast showed birds migrating out of our area last night so we’ll see if he’s still there this morning.
Daisies are blooming along meadows and roadsides, invasive wineberry is in bud, and bladdernuts have already formed green seed pods in the city parks.
On our walk in Frick Park on 23 May, Charity and I saw many deer including an obviously pregnant doe who looked ready to drop twin fawns. We wondered where she would hide them now that the browseline makes it possible to see right through the woods.
This deer-browsed Japanese knotweed shows how little food remains for deer in Frick. Normally they don’t eat Japanese knotweed but with few native plants left they are hungry enough to try it now.
At the end of winter Pennsylvania’s landscape has very little cover yet wildlife still needs shelter, especially from bad weather. Normally birds and animals would hide in thick bushes and shrubs but the deer population in Schenley Park is so high that they’ve denuded the thickets, including bush honeysuckle, even though it provides them with good shelter and is not a favorite food.
Without cover the deer were easy to see in Schenley Park’s barren woods in late March. The deer pictured below was camouflaged in plain sight until it moved.
Evergreen bushes could provide shelter but the yews have been browsed literally to death as the deer population has grown exponentially in Schenley in the past couple of years. The white backdrop at Frick Fine Arts building shows the damage typical of all yews near the park.
Now that the honeysuckle has leafed out it’s obvious that deer have eaten their own shelter. You can see straight through these bushes at ground level.
The effect of deer browse is also starkly obvious at Frick Park’s deer exclosure at Clayton East. The slideshow below gives west and north views of the fenceline, the plants growing inside the exclosure (I took a photo through the fence) and the barrens outside the fence. (I pivoted in place to show inside/outside.)
Ground-nesting birds can make a well hidden nest inside the exclosure but not outside.
The deer have eaten their own shelter as well as that of birds, rabbits and other animals in Pittsburgh’s city parks. There is nowhere to hide.
Black-legged tick season is here again and with it comes the threat of Lyme disease. We now find ticks in neighborhoods where they never used to be and white-tailed deer are the reason why. More abundant deer mean more ticks. More abundant ticks mean more Lyme disease. Though deer themselves don’t spread Lyme disease they have an effect on its abundance. Let’s examine the Deer, Ticks, Lyme connection.
Lyme disease is a debilitating illness caused by a bacteria (Borrelia burgdorferi) that’s transmitted by the bite of a black-legged tick.
Black-legged ticks (Ixodes scapularis and Ixodes pacificus) have a two year life cycle as egg, larva, nymph and adult. At each stage the tick must drink a blood meal to transition to the next one — from larva to nymph, from nymph to adult, and from adult female to produce eggs. (Note: Ticks eggs do not carry the Lyme bacteria.)
When a tick bites a host and sucks its blood it takes up the host’s blood and transfers some of its own body fluids into the host. If the host is infected with the bacteria, it infects the tick. If the tick is infected, it infects the host.
Deer are the adult ticks’ preferred host and their long distance transport system. Deer bodies are the place where adult ticks meet and mate in the fall. After mating the male dies but the female lives on. She sips a last blood meal, then drops off to the ground and hides in leaf litter while her body develops eggs over the winter.
Adult ticks meet in the fall during the rut while deer are moving around a lot. Bucks average 3-6 miles per day but may travel as much as 10-20 miles in search of does. Does may travel to meet or evade them.
Meanwhile ticks are along for the ride. When a pregnant female tick drops off after her last blood meal she may be 3 to 20 miles from where she started and she’s carrying 1,000 to 3,000 eggs that she’ll lay in the spring.
This week the weather stayed above freezing with an extraordinary high of 72F on 1 March. The plants and trees responded by bursting into bloom and leaf. Pictured here are:
A flowering cherry tree in Shadyside, 1 March
Coltsfoot in bloom at Moraine State Park, 1 March
Hairy bittercress blooming in Shadyside, 2 March
London plane tree seed balls disintegrating (a spring thing), 27 Feb
Now that the plants are waking up for spring Pittsburgh’s deer (over)population is finding more to eat. In front of Phipps’ Botany Hall I found a side-by-side example of yews, a favorite deer winter food, protected and unprotected from deer browse. One bush has no protection, the rest were wrapped in plastic fencing(*). You can already see the difference.
(photos by Kate St. John)
(*) The protected yews were wrapped on 15 December 2022 so, at the time of the photo, the unprotected yew was showing 10.5 weeks of deer browsing.
Aldo Leopold (1887-1948), quoted above, was a writer, philosopher, forester and conservationist. In the early 1900s he participated in a project to eradicate wolves from the American West. Back then it was thought that the absence of wolves would be great for our range cattle but no one considered what would happen to the landscape without the apex predator. Thirty years later Leopold wrote about it in A Sand County Almanac. We see the same results in Pennsylvania and in Pittsburgh’s parks today.
In the absence of hunters (wolves) the deer proliferated.
Deer still ate what they always ate, but the higher population consumed so much more.
The deer’s favorite food plants disappeared first; all new growth was consumed. The deer covered more ground and ate less favored plants.
After a couple of decades with constant browsing and so many plants missing, the landscape cannot regrow itself. The range failed within 20-30 years.
It’s not the mountain rocks that are afraid of deer. It’s the forest that fears for its life because deer are its predators.
When the deer population is in balance with the habitat, the forest is fine. When the population is too high the forest shows signs of distress on its way toward failure including browse lines and small bonsai-like trees, as seen in Schenley Park below.
Amazingly, it all started with the decision to remove an apex predator. We humans are the reason why there are too many deer and, so far, we haven’t had the will to reduce their population to a sustainable level.
In the meantime the forest is afraid for its life.
(photos by Kate St. John and from Wikimedia Commons)
At Thanksgiving in Kutztown, PA I was stunned to see a solid wall of arborvitae bordering a neighborhood. In Pittsburgh’s East End, arborvitae is always bare from the ground to 4-5 five feet up, eaten by our overpopulated deer. Here’s a row of arborvitae at Schenley Park golf course.
Why didn’t deer browse the Kutztown trees? My guess is that they are the Green Giant variety of Western arborvitaes. Davey Tree explains:
Deer don’t care for Western arborvitaes, like green giant, steeplechase or spring grove. So, if you plant these, they may leave them alone.
Though, when deer are starving, they become less picky and will eat almost anything, including those deer-resistant arborvitaes. If deer are a big problem in your yard, avoid arborvitae altogether.
In 1976 Jerry Kemperman and Burton Barnes discovered that 106 acres of quaking aspens (Populus tremuloides) in the Fishlake National Forest of Utah were actually all the same male plant, one root with thousands of suckers that grew into trees. It came to be known as Pando — “I spread.”
Pando weighs 6,600 tons making it the heaviest known organism on Earth and it is very old, though no one is sure whether it’s 10,000 or 80,000 or even a million years old.
However, almost as soon as Pando was discovered researchers found that sections of it were not rejuvenating because new sprouts were being overbrowsed by deer. In that part of the U.S. the species is mule deer (Odocoileus hemionus).
So they fenced it — twice — one fence in 2013, another in 2014.
Then in 2018 Paul Rogers and Darren McAvoy of Utah State University conducted a followup study sampling Pando’s health inside and outside the deer exclosure fences and concluded that the fencing was not working.
According to September 2022 Sci.News “The unfenced areas are experiencing the most rapid aspen decline, while the fenced areas are taking their own unique courses — in effect, breaking up this unique, historically uniform, forest. … Fencing alone is encouraging single-aged regeneration in a forest that has sustained itself over the centuries by varying growth.”
“One clear lesson emerges here: we cannot independently manage wildlife and forests.”
Aldo Leopold’s experience in his early career when he worked to eradicate wolves from the American West changed his perspective on trees and deer. At one point he shot an old female wolf and was there to see the green fire go out of her eyes as she died. He wrote …
I thought that because fewer wolves meant more deer, that no wolves would mean hunters’ paradise. But after seeing the green fire die, I sensed that neither the wolf nor the mountain agreed with such a view.…
I now suspect that just as a deer herd lives in mortal fear of its wolves, so does a mountain live in mortal fear of its deer. And perhaps with better cause, for while a buck pulled down by wolves can be replaced in two or three years, a range pulled down by too many deer may fail of replacement in as many decades.
It’s mid November and the rut is at its peak in Pennsylvania. Bucks sniff the air for females in estrous (flehmen), chase does in heat, and hide with them in thick cover to breed repeatedly. Some run into traffic, including yesterday’s road-killed 6-point buck in Schenley Park. Meanwhile birders in Frick Park are seeing all of this up close. Very close.
On 10 November Charity Kheshgi and I encountered a group of five. Two does and an 8-point buck were hiding in a thicket when a 4-point buck walked onto the trail behind us, sniffed the air and looked down at the females. Meanwhile another doe (at top) walked onto the trail ahead of us. This could have been dangerous for the two of us. Fortunately the deer did not view us as competitors.
The 8-pointer was hard to see in the underbrush but he resembled this 10-point buck Mike Fialkovich saw on 5 November that appears to be flehmening.
Deer are a prey species, alert to the presence and intent of predators. “Is the predator here? Is it hunting?” And they move to locations of least danger. We see them up close in Frick Park because they have learned that humans in Pittsburgh’s city parks are not dangerous even during hunting season.
Meanwhile, hunting is currently in progress statewide and it’s good to be aware of it. We have so many deer in our area — Wildlife Management Unit (WMU) 2B — that hunting lasts longer here than in most of the state.
Here’s a quick summary of deer hunting times and types, now through January, in WMU 2B both Antlered and Antlerless unless otherwise noted.
now – Nov. 25, including Sundays Nov. 13 and Nov. 20, WMU 2B: Archery
Spanish cellist Diana Gomez plays music outdoors in many venues. Here’s what happened when she took her cello into a forest and played Bach’s Suite No.1.
If you’ve been watching white-tailed deer (Odocoileus virginianus) in the City of Pittsburgh you’ve noticed that they’ve changed their behavior since early September. Back then deer were easy find in groups during the day but now in October they seem to have gone missing. Soon — very soon — they’ll be running into traffic. All of this is part of their breeding season, called the rut, which is driven by photoperiod.
In late summer, white-tailed deer hang out in bachelor groups of adult males and matriarchal groups of does with fawns. As the rut goes through phases, described below, the dynamics change. In the city we live with so many deer that it’s good to know the phases.
Pre-Rut Phase: In late September and early October testosterone levels rise in the bucks, they rub on trees and shed velvet from their antlers. The bachelor groups break up as each male goes it alone and adjusts his home range. During this phase the bucks eat a lot, especially acorns. Once the rut begins they’ll be too busy to eat while chasing, breeding and tending does.
The buck rubs were fresh in Schenley Park on 9 October 2022. Right after this the bucks “disappeared” from the park.
Bucks also spar to settle their pecking order as shown in this photo from Tennessee. I have never seen sparring in the city parks.
Seeking and Chasing Phase: As the females begin coming into estrous the males search for and chase does in heat. The bucks move around lot, averaging 3-6 miles per day. Meanwhile doe+fawn groups break up as adult females become distracted. Watch out! They may run into traffic.
The late summer groups have already broken up in Schenley and Frick Parks. The only deer I’ve seen recently are lone females or almost grownup fawns.
At the peak of the rut bucks make long excursions out of their home range in search of females, sometimes 10-20 miles. The peak also includes a “tending” phase during which bucks and does pair up and hide in thick cover to breed repeatedly.
Post-Rut Phase: Activity drops off precipitously in early December after most of the does have bred. Adults stop wandering and settle into their home ranges. The males still have antlers and some will search for recently-matured fawns that come into estrous (red color in graph above), but the frantic edge is gone.
When will we see deer in lazy groups again in the city parks? Wait and see.