Guide to Birding Plummer’s Hollow

General Considerations

What counts as the eBird hotspot?

Any bird detected on or from Highway 453 (10^th Street in Tyrone) and Pennsylvania Avenue, going southeast, on or east of I-99, including a 1-mile stretch of the Little Juniata River downstream from the PA Ave bridge in Tyrone to the HWY 453 bridge, and Brush Mountain for about 2.2 miles south.

Are parts of the hotspot off limits, even to Friends of Plummer’s Hollow?

For general visitors by land, parking is permitted at the I-99 Park-and-Ride or at the gravel turn-off east of Plummer’s Hollow Bridge. Take care walking along the highway berm. It is also permissible to park along the township road that connects the bridge with the tracks, if traffic flow isn’t impeded. At the tracks, people often park on or near the railroad right-of-way; this may be subject to restrictions, and whatever you do, don’t block the gravel routes used by Norfolk Southern on both sides of the tracks. No parking is currently available outside the gate on the south side of the tracks.

For invited visitors and those Friends members with gate keys, it is preferable to park in the area directly above and to the right of the gate. If there are special circumstances, you can drive up the road and use one of the various pull-offs, or park in the field at the top.

For visitors by water, you can row, raft, or otherwise go from Tyrone to a put-in spot just below and to the right of the bridge, or continue on out of the hotspot. The owners of the land along the river include PennDot and the New Enterprise company.

Getting around the hotspot by land involves hiking, ranging from easy (the Plummer’s Hollow Road and some of the upper trails) to extremely strenuous. Some of the best birds and most spectacular birding experiences are accessible via strenuous hikes (or shortcuts) and require proper footwear and good physical condition.

Are there any risks I should know about?

Ticks that may carry Lyme disease are common, particularly in the spring, so proper protective measures should be taken, including staying on open trails.

Bug spray for mosquitoes, black flies, deer flies, and other pests is a must from May on.

No poisonous snakes occur, but visitors should be on the lookout for low-hanging, bald-faced hornet nests in late summer, and the occasional bear. Permitted dogs should be leashed, due to the large porcupine population.

The areas between the tracks and the river, and along 453, are somewhat notorious, so it is important to keep your vehicle locked and valuables out of sight. The Bonta property is patrolled and safe (from the tracks southward).

I want to walk in the Hollow. What birds can I see there?

The answer, as you might have guessed, is “it depends.” The eBird lists you might see for the hotspot are typically from very early in the day (before 8 AM) and from places other than the Plummer’s Hollow Road. They are also often compiled from what we hear, and even what we record flying over at night.

If you get to the hotspot an hour before sunrise, you can see and hear (trains permitting) plenty from the gate area both above and below the tracks. Birds leave their night roosts and fly through the Tyrone Gap (both directions) from first light until sunrise. By sunrise, most birds are already feeding, and in some months, that means they’re harder to see. They sing until an hour or two after sunrise, after which time only the most energetic individuals continue to make noise through the day.

Raptors can be seen soaring throughout the day, particularly when it’s windy, and during the peak migration periods of March-April and September-December.

If you walk the Plummer’s Hollow Road between April and July, you will almost certainly see Louisiana Waterthrushes and Acadian Flycatchers, and you may hear, if not see, Blackburnian Warblers. Scarlet Tanagers, Worm-eating Warblers, Ovenbirds, Yellow-billed Cuckoos, Barred Owls, Wood Thrushes, and other deep woods specialties, all of which are common. Dawn or dusk are generally the best times to catch a glimpse, but if you sit and wait in a single spot, you may see these or many other species (Rose-breasted Grosbeaks, Hooded Warblers, Black-throated Green and Black-throated Blue warblers, and so forth) flit back and forth from the upper slopes to drink water and bathe in Plummer’s Hollow Run. This happens more as the summer progresses, once the stream becomes the birds’ sole source of water, and as fledglings, molt-migrants, and long-distance migrants are on the move.

Birding by ear is always a possibility, though during times of high water, few species can be heard above the stream.

Outside the breeding season, migrant peaks occur April 15-May 15 and Aug. 20-Oct. 20. Noticeably more birds are about at these time, and in the fall they are often easy to see, though not as vocal as they are in the spring, and often in drab plumage.

In the winter months, the Plummer’s Hollow Road can be an easy walk or a slippery trek. Winter Wrens are common, as well as Hairy Woodpeckers, Golden-crowned Kinglets, and Brown Creepers during most years.

How do I get to the good stuff?

Nature hikes of different types are scheduled at irregular times of the year, or by special request. These may start from the bottom of the Hollow, or from the top, and can range from one to many miles and hours in length.

Special requests may include primitive camping and full trail access for teams engaged in birding competitions, researchers carrying out studies, or something else. All bird-related inquiries should go first to markabonta@yahoo.com.

We have kept over 50 years of daily observations that help pinpoint and predict the locations of individual species.

FAQs for Advanced Birders

A bird I need for my (county/state/life/year/etc.) list just popped up for Plummer’s Hollow. How can I see it?

First, check that it wasn’t recorded via NFC (nocturnal flight call).

Contact markabonta@yahoo.com immediately to see if it’s possible to visit (it usually is, if the bird has hung around). Depending on where it’s located, and whether the road is drivable (increasingly, it is open most of the winter), you may not have to walk long distances or cross strenuous terrain. The rarest species tend to be easily locatable along the edges of the field, a 20-minute stroll from parking.

For regularly predictable species, it’s best to coordinate well ahead, where possible. This includes particularly during peak times when the Plummer’s Hollow’s migrant-trap phenomenon result in a staggering number and diversity of otherwise scarce species.

How many species are there?

The Plummer’s Hollow Private Nature Reserve is consistently in the top 5 spots for birds in Pennsylvania, despite being a fraction of the size of its main competitors (Presque Isle SP, Middle Creek WMA, John Heinz NWR). A single person can detect 200+ species in the hotspot in an average year, but doubtless many more pass undetected, as we have few eyes and ears to help during peak periods.

The true number of species overall is no doubt much higher than the all-time total of around 225 species we’ve recorded since 1971. Most recent additions are from NFCs, which we only started monitoring in 2020. However, we also see a trickle of new species every year—in 2024, for example, Red-breasted Merganser and Clay-colored Sparrow were firsts for the hotspot.

What birds are you missing?

We have no tilled farms fields or extensive grassy meadows, almost no wetlands, and no sizable expanses of water. This explains why the site list still does not include some common waterfowl species (like scaup) and why common field and water species (like Wilson’s Snipe, Bobolink, Grasshopper Sparrow, Long-tailed Duck, and Snow Bunting) have only been recorded during night flights. Several of the missing species just happen to be those that haven’t (yet) crashed down onto the river during a fallout, don’t vocalize while flying at night, or otherwise slip by undetected. But the list is narrowing, and hopefully, with improved detection techniques and gradual enhancements to our wetlands, we can attract more of this missing component of the avifauna.

Why are your lists so long?

Plummer’s Hollow eBird lists tend to have excessive numbers of species and individuals on them, which is partly a function of species richness but also has to do with the fact that they are mostly conducted on foot over the course of several hours, connect several distinct habitats, include heard birds, and are made by people with intimate knowledge of the locations of individual birds from year to year.

Nevertheless, all else being equal, Plummer’s Hollow still seems to have an outsized avian richness, which can be explained by location, location, and location…and habitat stewardship.

What makes Plummer’s Hollow so special?

The Bald Eagle-Brush Mountain ridge system, the westernmost in the Ridge-and-Valley section of the Appalachians, is a major corridor for raptor migration, explaining phenomena such as two separate Swallow-tailed Kite records, and high numbers of Golden Eagles in the Fall.

Our forests have benefited from the benign neglect of a half-century of letting trees die, fall, and rot in place, with little harvest, even for firewood. Thus, the woods that are richest for birds (particularly that which grows on the crumbly sandstone of the Ordovician Juniata Formation making up the east slope of Sapsucker Ridge), despite some selective harvesting by former owners, have a complex, multi-layered structure, often including a wealth of native understory such as spicebush and witch hazel, along with many gaps and treefalls.

As we have left the forests to regenerate, we have also controlled ~~hoofed locusts~~ white-tailed deer through a long-running hunting-by-invitation-only management program. This has helped maintain diverse plant species composition, though it is also related to the thickets of invasive plants such as privet and barberry. One of Plummer’s Hollow’s constant struggles is control of invasive plant species and replacement with natives. Meanwhile, though not ideal, the invasive thickets do harbor considerable bird diversity on their own, including the highest numbers of Eastern Towhees in the state during October migration.

The other major important habitat component is First Field, which has strict invasive control and has transitioned during the last 50 years from mostly grass to mostly goldenrod. The goldenrod tends to keep out herbaceous invasives, and we cut out most of the woody invasives, save an occasional walnut. We also keep the native blackberry patches, which in 2024 attracted nesting Yellow-breasted Chats for the first time in almost 30 years. The goldenrod grows so thickly that it serves as cover for birds that stage during the massive fallouts of autumn and for winter sparrows and others that linger well into the depths of winter. Notably, this includes Connecticut Warblers and Lincoln’s Sparrows in early October. They’re attracted not just to the cover but also to the abundant insect life.

What’s the “migrant trap” phenomenon all about?

A narrow strip of habitat on the east slope of Sapsucker Ridge, basically an ecotone of field edge, wild grape tangle, and tall woods, stretching from the top of First Field northeastward for over a mile to Dogwood Knoll, harbors the vast majority of individuals and species on the property during the year, and particularly during peak migration periods. Birds fall out here constantly while moving both north and south, attracted to available cover as well as feeding opportunities.

One of the main reasons we think that the Sapsucker Strip is so attractive to them is the presence of many towering wild black cherries, which in other forests have been systematically harvested for their valuable wood. In Plummer’s Hollow during the Labor Day peak, a single black cherry can hold 50+ transient as well as resident species at a time (no exaggeration), including birds foraging on the ripe cherries themselves, on the gnat clouds attracted to the fruit, and on other birds.

Other aspects of the migrant trap involve its location as a possible preferred staging ground (particularly August-October)—a known, dependable stopover point with not only abundant resources but also shelter and safety. Going south, forest birds likely remember and also communicate to other birds the existence of certain major “buffet” locations like Plummers’ Hollow, where they can fatten up in preparation for the long journey, just as they might at coastal locations and wetlands.

Do you have a watch site?

There is no single promontory from where you can see all raptors in flight over the hotspot. We do have preferred locations, however, the most accessible of which are along First Field and at the gate area along the tracks. For Fall migration, an excellent site is the Big Rockslide, a location with a sweeping view of the flight path from the north, where you can easily spot a couple dozen Golden Eagles up close on a good day. The rockslide is accessible via a 40-minute walk-in.

What is the trifecta?

If you start early on certain warm and windy days in September, you can witness three major birding spectacles in a single morning: Descent of the Thrushes, Warbler Madness, and Broad-winged Hawk kettles.

In the last hours and minutes before the dawn chorus of land-based species begins, and even overlapping with the first local towhees and whip-poor-wills, Veeries and Swainson’s Thrushes by the thousands pour through, along with a few Gray-cheeked Thrushes. They peep back and forth to each other and to those already on the ground, and dozens or even hundreds settle quietly in the trees all around, while others continue to the next ridge south. On good mornings, often foggy ones, the chorus of thrushes overhead is almost otherworldly, and if you’re lucky, they’ll sing some bars of their ethereal songs once they’re ensconced in the vegetation. The phenomenon starts in August and early September when it’s dominated by Veeries, then by mid-September it shifts to Swainson’s Thrushes; Hermit Thrushes peak in October.

As the thrushes fall silent, warblers begin to chip and buzz all about; in the fall, they arrive in huge numbers—whereas in the spring it might take all day to hear (and you’re lucky if you see) a handful of Nashville Warblers, in the fall you can see that many at one time in a single black locust tree. Warbler activity is best just before and after sunrise, but if you sit in the right place, you can watch mixed-species warbler flocks move through the black cherries over much of the morning. They’re accompanied by dozens of other species, with often dizzying numbers of Rose-breasted Grosbeaks, Scarlet Tanagers, orioles, flycatchers, and vireos. Where you might struggle to see one Philadelphia Vireo, if you catch the right day you can see several moving through a single tree together. On one day, you might see several Wilson’s Warblers in a downed catalpa; the next, they have been replaced by Mourning Warblers, or Northern Parulas.

Once it heats up, look to the skies. The best place for broad-wings is the Far Field; they pop up unexpectedly above the towering canopy of the ridgetop in kettles of 10, 20, 50, and you get about a minute of viewing before they’re out of sight. For longer sits (bring a foldable chair), the neck of First Field affords sweeping views north toward Bald Eagle Mountain, where you can watch raptor clouds approach from miles away. As with many migratory ridges in the state, hundreds or even thousands of hawks may move through in a given day.

Resources

Bird Mountain. Mark Bonta’s blog started as a quest to detect 200 species on the hotspot (the Plummer’s Hollow 200) in 2023. Bird journals several times a week included intimate details of birds seen from the Tyrone corner of the hotspot and detected from throughout the area, both by day and by night. The 200-species goal was reached by early November. In 2024, a format of weekly updates kept readers updated.

Plummers’ Hollow eBird hotspot. This is the main record of what’s been recorded in the hotspot since 1971. Several accounts cover not only current, live records but also NFCs and historical records. The Illustrated Checklist and Bar Charts are particularly useful ways of seeing the data. You will note that birding activity has increased steeply since the advent of eBird use in 2015: Mark Bonta’s eBird lists alone went from eight in 2015 to 71 in 2019, 348 in 2020, and 580 in 2023. The Bonta family’s historical records, primarily Marcia Bonta’s notes, have also been entered as thousands of checklists, but these lack the fine-grained detail of species richness and numbers of individuals we have amassed since 2020.

Marcia Bonta’s Pennsylvania Game News columns. Years of monthly columns are available here, and many include in-depth accounts of numerous Plummer’s Hollow bird species. Marcia Bonta’s website also contains info on her books, particularly the Appalachian cycle.

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