Postponed Winter Walk- Still Cold!

When I postponed the January winter walk I was hoping for warmer weather and we got it; the thermometer was 20 degrees higher than last Sunday.  But it was still only 15 degrees and despite that over 20 energetic people showed up for the walk in the Arnold Arboretum.  Fortunately I had a co-leader on the walk, Brendan Keegan who in addition to being a good birder is an Arboretum Gardener. On the walk he talked with the group about some of the woody plants in the collection that provide food and shelter for our avian friends.  Here is a pictorial spread of some of the shrubs he discussed during the walk:

Clockwise from upper left; Amur Honeysuckle Lonicera maackii, Harlequin Glorybower Clerodendrum trichotomum, Purple Beautyberry Callicarpa japonica var. luxurians, Common Winterberry Ilex verticillata, Cultivar of Holly Ilex ‘Lidia Morris’, Lindera umbellata.

All of these beautiful shrubs, and many more, provide food for fall migrants in preparation for their long migratory travels, as well as for our winter residents.  Brendan noted the variation in berry maturation time of these plants and how that is good for the birds as well as the plants themselves by fostering seed distribution.  In the Children’s Field Study Program we have a name for that- Eat and Excrete- much fancier than eat and poop!

Far and away the best birding on this cold morning was at the Hunnewell feeding station and we spent time there at the start and finish of the walk.  In fact, every species we encountered were on or near the feeders at one time or another, although several were also seen elsewhere in the landscape.  At the start we had good looks at both common local finches, House Finch and American Goldfinch,  as well as chickadees, and Downy Woodpeckers.

Male House Finch

American Goldfinches in various non-breeding plumages. A Dark-eyed Junco is at bottom left.

Male Downy Woodpecker; the females lack the red crest.

Someone inquired about the nesting habits of chickadees; they are cavity nesters, utilizing old woodpecker holes or man-made houses.

Black-capped Chickadee at nest hole

These young chickadees are almost ready to fledge from their soft and warm nest made of moss and grasses. The house was in the Leventritt Gardens at the AA.

The only bird that wasn’t seen on a feeder, but was nearby, was a Red-tailed Hawk.

This Red-tailed Hawk is closely guarding its prey, a hapless Gray Squirrel

The hawk was studying the grassy slope and wet meadow for prey. They have huge eyes in proportion to their bodies and can see at least five times better that we can, and can magnify their view as well.

As we proceeded on the walk up to the ponds we stopped to look for the Eastern Screech-Owl that has taken up winter residence in a tree hole near the ponds for at least four years.  The owl hasn’t been seen as far as I know for at least a month; here is the last image I got of it, taken on November 8, 2017:

Red-phase Eastern Screech-Owl. Screech owls have an average life span of about eight years; perhaps the owl has expired, or it may just be using a different roost hole.

As we turned around after reaching the frozen over ponds, we stopped to admire one of the first trees in the collection to flower:

Ozark Witchhazel Hamamelis vernalis, in bloom in January 2018 in front of Rehder Pond. This particular native specimen is over 100 years old.

On our return trip Brendan talked about other trees in the collection useful to birds. He pointed out several oaks and spoke to the importance they have providing lots of real estate for nesting well as food for birds and other fauna in the Arboretum.  Acorns of course are well know to almost all of us, but did you ever see one like this:

Sawtooth Oak Quercus acutissima 1130-60   This tree is at the base of Peters Hill near the railroad tracks, and is Asian in origin.  Even acorns can have a bad hair day!

We also discussed the relationship between birds and non-native and invasive plants.  Here is a composite image of a few of them:

Clockwise from left: Oriental Bittersweet, Barberry, Euonymus, Porcelain Berry.

The common view that invasives are universally harmful is too simplistic. True, they sometimes crowd out native, often more nutritious plants, but birds still utilize them for food, especially during drought or harsh weather.  In fact some birds have been able to spread their territories due to the availability of invasives; multiflora rose and mockingbirds are a case in point.

Northern Mockingbird on a native crabapple tree on Peters Hill.

Birds just love fruits and berries, and are as open to ethnic food as most of us!

Cedar Waxwing dining on Tartarian Honeysuckle.

We ended the walk back at the feeders and picked up our best bird of the day, Red-breasted Nuthatch.

Red-breasted Nuthatch.  Smaller than it’s much more common cousin the White-breasted Nuthatch, it is identified by the striking white eyebrow, black eye line and ruddy breast.

One of the reasons I run the January walks is to help people start their Year Lists; what crazy birders do every New Year to list how many species they can see or hear during the year.  Serious listers can amass over 300 species just in Massachusetts (I haven’t even come close to that)!  RB Nut, as we call it, is always a good one to get early on as it is seldom seen in the warmer months.

After the walk a few folks came into the Visitors Center to warm up; from the window you can view the feeders close up, which we did.  A new species, Red-bellied Woodpecker, flew in, grabbed a bite, and was off; but as three of us saw it it made the list!

Male Red-bellied Woodpecker, showing red from crown to nape. The faint rosy color on the breast and belly can barely be seen, giving the bird its odd name. This image was taken in the spring on Cape Cod.

Here is the list for the walk:

Arnold Arboretum, Suffolk, Massachusetts, US

Jan 14, 2018 9:00 AM – 10:15 AM

Comments:     BBC walk, 15 F, sun

  • 17 species
  • Red-tailed Hawk  1
  • Herring Gull  1
  • Mourning Dove  2
  • Red-bellied Woodpecker  1
  • Downy Woodpecker  2
  • Blue Jay  2
  • Black-capped Chickadee  6
  • Tufted Titmouse  3
  • Red-breasted Nuthatch  1
  • White-breasted Nuthatch  1
  • European Starling  6
  • Dark-eyed Junco  35
  • Song Sparrow  3
  • Northern Cardinal  2
  • House Finch  20
  • American Goldfinch  15
  • House Sparrow  2

View this checklist online at

This report was generated automatically by eBird v3 (

Those of you who bird the Arboretum regularly should keep a lookout in the conifer section for both crossbill species in the next few months as a major irruption is predicted this year.

Female, upper left, and male White-winged Crossbills. The female is showing the weird bill, specially adapted for prying seeds out of conifer cones.

A former Arboretum staff member, who now works for the Cornell Lab of Ornithology, has just written an excellent article on the expected irruption.

 And we are hoping for another nesting of Great Horned Owls in that area this month as well, here is a shot of the nest in 2016:

Great Horned Owl on nest in 2016. The head of the adult female is seem, with a lighter colored fuzzy owlet in front of her. There were three owlets altogether.

I saw an adult roosting in one of the King Boris Firs on conifer slope just last week, so they may nest somewhere nearby.

And soon we will be seeing and hearing the true harbinger of spring, Red-winded Blackbird.

Male Red-winged Blackbirds displaying in the wet meadow across from the Hunnewell Building.  The males arrive as early as the end of February.

Spring Walks will commence on Saturday April 28th at 8AM at the Main Gate.  See the AA website soon for the whole list.

Good Birding!

PPS: What’s in the picture?

In my last post on the evolution of the Pipevine Swallowtail caterpillars I also included three images of a female Ruby-throated Hummingbird that I photographed on the same Harlequin Glorybower bush that harbored the Pipevine butterfly.  A keen 11 year old observer from Maine contacted me, kindness of her grandmother, to point out something in the images I had completely missed.  On the left side of the pictures the head, thorax and powerful front leg of a Praying Mantis are clearly visible:

The Praying Mantis and the Ruby-throated Hummingbird appear to be staring each other down.

This young naturalist took it one more step; she expressed worry that the hummer might fall prey to the preying Praying Mantis, and asked Grandma to query me on that issue.  As I read the email I mused that a child would be so naive as to think that a feisty hummingbird could possibly fall victim to a fierce, but much smaller, insect.  Then I read on; for backup she pointed me to a recent article in the New York Times:

I heartily recommend that all readers of this blog read this Science Times piece, not only for the raft of fascinating information about these critters, and the complete confirmation of my friend’s fears, but also to view spectacular photos of exotic mantid species worldwide.

Speaking of mantid pictures, this is the second time in a week that I have stumbled on, or been led to, a Praying Mantis in a photo I took when I hadn’t noticed it in the field:

With this photo I was documenting a Painted Lady Vanessa cardui butterfly, one of hundreds migrating through Boston right now, on a Butterfly Bush at the Boston Nature Center. Only when I got home and uploaded the image on my computer did I notice the Praying Mantis Mantis religiosa above.  Camouflage or inattention?

As to your concern, Grace, I can’t say for sure that the hummingbird survived to fly south sometime last week, but I do know it flew away from the predator while I was present.  And as the NYT article reports, predation of birds by Praying Mantises is pretty rare; they are prowling around in flowering bushes looking primarily for more reasonably sized fare- bees, wasps and probably butterflies!

Thank you for drawing all of this to my attention.

How rare is rare? – a butterfly tale

As spring slides into summer birds go quiet; nesting, rearing their young, preparing for their southern migration or just hanging out.  I switch to Lepidoptera and Odontata to keep me busy.  Butterflies and dragonflies have elaborate life cycles; eggs become larvae which grow, sometimes over long time periods, bigger and bigger and finally transform to often spectacular adults who spend their short lives looking for mates, mating- and for the females- laying eggs to renew the cycle.

I’ve discussed dragonflies in two previous posts.  Recently however, I went in search of a butterfly that has eluded me for more than ten years.  The Pipevine Swallowtail is one of five species of Swallowtails, Papilionidae, that can be seen in the Boston area.  Perhaps the most common of this group is the Eastern Tiger Swallowtail:

Eastern Tiger Swallowtail Papilio glaucus

There are two other relatively common swallowtail species in the area; one is the Spicebush Swallowtail:

Spicebush Swallowtail, Papilio troilus, on Swamp Milkweed

It can be tricky to distinguish that predominantly black butterfly from the named Black Swallowtail:

The small yellowish/whitish single spot near the top of the forewing is one way to differentiate this female Black Swallowtail, Papilio polyxenes, from the Spicebush species

To make matters worse, there is a notable gender difference in this last species:

Note the broad yellow median band on the wings of this male Black Swallowtail, and the sub-apical spot characteristic of the species.

Early in July I went to the area where I thought I would have the best odds of finding a Pipevine Swallowtail.  Pipevines, like most butterflies, have specific plants on which they lay their eggs, so called host plants.  Most plants produce toxic substances to reduce their chance of being eaten by predators like the caterpillars of moths and butterflies.  To get around this defense, butterflies evolved over time a resistance to the toxins of one or more plant types; they aren’t deterred by the poison and in fact benefit from eating it because they in turn take the nasty toxin into their bodies thus protecting them from being eaten by birds or other predators.  Many butterflies have several host plants; the Pipevine has only one, the genus Aristolochia or Dutchman’s Pipe, named for it’s flower which is thought by some to resemble a meerschaum pipe:

Aristolochia macrophylla in bloom

The Editor of the Arboretum’s scientific publication Arnoldia has recently written a great post on her blog ARblog which describes this symbiotic relationship in detail.

The Arboretum has a number of these vines growing on the chain link fence surrounding the garage near the main entrance.  I’ve searched them every summer since I learned of the swallowtail connection- in vain.  But this time I spotted something interesting fluttering around the massive leaves of Aristolochia macrophylla:

Pipevine Swallowtail, Battus philenor, on Pipevine

Could this be my illusive lep?  A moment later it perched and I got a closer look:

Female Pipevine Swallowtail, ovipositing on Dutchman’s Pipe

The butterfly was laying eggs on a stem of the vine!  Identity confirmed!

When I returned home I tried to determine just how special my sighting was.  I went to the website Butterflies and Moths of North America and focused in on sightings in Suffolk County, Massachusetts.  There was only one historical listing in over 23 years, a sighting verified in 2004.  Another check on sightings for the entire state since 2010 uncovered only 28 reports.  I was on to a big time rarity!  I emailed some friends who work at the Arboretum, posted the sighting on MassLep (a local list server), and reported it to the above website along with some images.

A week later the Manager of Plant Records at the Arb, and fellow naturalist, emailed me an image of a Pipevine Swallowtail he caught nectaring on an azalea flower at the top of Bussey Hill:

Pipevine Swallowtail Battus philenor on Rhododendron arborescens Photo by Kyle Port

So this was now the third sighting of this swallowtail in Suffolk County?  And as if that wasn’t enough, the next day I received word that two seasoned horticulturalists on the AA staff had discovered Pipevine Swallowtail caterpillars on the same vines near the garage back in 2010, and had even over-wintered one which emerged from it’s chrysalis the following spring!  They have found one or more as caterpillars almost every year since then.  But they record stuff in botanical journals.

Suddenly my rare discovery seemed mundane.  Maybe this swallowtail was pretty common, but no one bothers to report it to obscure websites.  I backed off my high to gather some perspective.  I had never seen it, and I’ve been looking at butterflies for many years.  A cursory review of MassLep reports in the last few years revealed only 3 reports, and they were HIGHLIGHTED in each case.  So yes, this was a rare sighting, but perhaps the Arboretum, with it’s abundant pipevine plantings, may be a local mecca for this lep.  In fact, when I made a presentation on site about my find recently, one of the attendees reported he had seen what he thought might have been a Pipevine Swallowtail as he approached the meeting site.  I pointed out that other more common black butterflies were more likely.  But after the meeting some in the group went with him to where he had his sighting and found and photographed the creature.  After review, the image turned out to be our index swallowtail!  I’ve been back a number of times to follow the development of the eggs and have seen several more likely suspects in flight but have not been able to confirm their identification.

Speaking of the eggs, they have hatched:

About 20 of the 50 or so eggs that were laid by the female butterfly

Five days later most of the eggs have hatched into first instar cats.

A dozen second or third instar cats still hanging out together a few days later.

This little guy has a delineated head at one week of age, and has wandered away from the herd.

Another colleague at the Arboretum has agreed to share her Monarch caterpillar inclosure on display in the Visitors Center, and we have put about a dozen of the Pipevine caterpillars inside along with host plant offerings.  Will they pupate?  Stay tuned, or better yet, come and visit the display when you’re nearby.

The butterfly inclosure at the Visitor’s Center in the Hunnewell Building.

Four of the transplanted Pipevine caterpillars seen through the screen inclosure.

As I mentioned at the beginning of this long post, there are five swallowtail species that can be seen on the Arboretum grounds.  I still have one to go, although I did see it a few years ago while vacationing in Pennsylvania:

Giant Swallowtail Papilio cresphontes. Although this is a very poor photo, it is enough to confirm the identity of the specimen. The yellow spot within the tail, seen to the right of the lower berries, is diagnostic.

Giant Swallowtails have been reported in the Arboretum for the last two years; it is a species that seems to be increasing in our area.  Their host plants are Prickly Ash and Hop Tree; both are represented in the collection.  I’ll be keeping a look out!

Good butterflying!