Birds

By Matt Bailey, Delaware Nature Society Volunteer:

It is the depths of winter.  What better time to wrap your hands around a warm mug of your favorite comfort drink?  If you live in the US, that hot drink is statistically most likely to be coffee.  The warmth (and steam) wafting from your mug might put you in the mind of mid-Atlantic Spring and Summer and the wealth of songbirds they will bring.

Right now, Neotropical (western hemisphere) migrant birds like orioles, warblers, and hummingbirds are making their livings in Central and South America.  Many Paleotropical (eastern hemisphere) migrants are also awaiting the call to head north from their wintering grounds (pun intended).  Ecuador, Guatemala, Sumatra, Ethiopia are all on the list of important wintering locations as well as famed regions for coffee farming.  In Central and South America, most Neotropical migrants depend on tropical forest to successfully over-winter and survive to head north and breed.  Significant portions of Central and South America have been cleared of forest to make way for coffee monocultures.

This is a shade-grown coffee plantation that was visited on a DNS trip to Costa Rica in 2011. In order for the habitat to be functional for a diversity of songbirds, the overstory trees need to be diverse and native. Some shade-grown canopies consist of Eucalyptus trees, which aren’t native and don’t support a diversity of insects or bird-life.  Photo by Joe Sebastiani

We can speak up for these overwintering songbirds with our dollars in the marketplace and in the coffeeshops.  The most typical method for growing coffee involves taking a large parcel of land in the right habitat and shearing off the canopy trees to make room for coffee shrubs.  This eliminates key habitat for overwintering songbirds.

American Redstart is a Neotropical migrant that will utilize shade-grown coffee plantations in Central America. Photo by Joe Sebastiani

Fortunately, it doesn’t have to be this way.  There is a coffee growing method called shade-grown, or bird-friendly agriculture.  In this type of farming, coffee varieties can be chosen and growing regimes can be adjusted that allow the majority of the growing areas to remain forested.

The resulting crop yields award-winning coffee that lacks the bitter taste of unnecessary loss of habitat.  A win\win that affords us the chance to steep peacefully in the aroma of a sustainable harvest.

The Smithsonian Institute has the gold standard for certifying coffee plantations as being bird-friendly.  Just look for the logo below on the package to be sure you are purchasing the correct beans.  In addition to retaining canopy, Bird-friendly certification standards consider a variety of factors including promoting insect biodiversity and forgoing the use of pesticides.  The American Birding Association, whose national headquarters is in Delaware City, sells numerous varieties of Bird-Friendly coffee on their website and at the headquarters.

Shade-grown/bird-friendly coffee can be found at several local grocers and the local roaster Golden Valley Farms in West Chester.  Just make sure that the coffee you buy has the Smithsonian Bird Friendly certification on it.  Also, if you stop into your favorite coffee shop, be sure to ask if they have any shade-grown brews available.  If enough customers ask, an affirmative answer will likely eventually follow.  Put your dollar votes to work for conservation!

Speaking of birding, this Friday through Monday, February 15-18, 2019, Delaware Nature Society is participating in the Great Backyard Bird Count. This is an international effort to capture a snapshot of birds that are being seen around the world, organized by the National Audubon Society. If you participate, Birds & Beans Coffee company is offering a $5 coupon if you order Bird Friendly coffee on their website.  Just use the promo code GBBC$5OFF for your on-line order, which is good through the end of February.  You can participate at home on your own (see previous link) with a nice cup of Shade-grown coffee, or join us for some guided birding opportunities:

“Pop-Up Birders” will be coming to where you live, work, and play on February 15 at the following locations:

  • Newark Reservoir Parking Lot, Old Paper Mill Rd., Newark – 9am – Judy Montgomery
  • Brandywine Town Center Movie Theater – 10am – Joe Sebastiani
  • Tri-state Bird Rescue, Possum Hollow Rd., Newark – 11am – Judy Montgomery
  • BlackRock Incorporated, 100 Bellevue Parkway, Wilm. – noon – Joe Sebastiani and Kathie O’Neil
  • Dupont Environmental Education Center, Wilm. Riverfront – 1pm – Ian Stewart
  • Paper Mill Park, Polly Drummond Hill Road, Newark – 2pm – Judy Montgomery
  • Valley Garden Park, Rt. 82, Greenville – 3pm – Jim White

By attending one of these walks, receive a voucher for a free sample bag of bird seed at the Wild Birds Unlimited store in Hockessin.

We will also host a Breakfast and Bird Count program on Friday, February 15 with Ornithologist Ian Stewart at Coverdale Farm Preserve.  $15 ($10 for DNS members) includes the hearty breakfast and a guided bird walk in our beautiful preserve near Greenville.

Want a bit more adventure? Join us for Kent County Birding Day, Saturday, February 16. Meet at either Abbott’s Mill Nature Center or Ashland Nature Center and travel by van to Bombay Hook National Wildlife Refuge and other locations to look for waterfowl, eagles, and many more wintering species.  $30 ($20 for DNS members) includes van transportation as well as the guided birding tour.

For more information, please call (302) 239-2334 or visit www.delnature.org.

Ian Stewart

These are the opening words of the poem ‘To a mouse’, written by the legendary haggis-eating Scottish poet Robert Burns in 1785 (which also contains the famous line oft-paraphrased as ‘The best-laid schemes of mice and men go often askew’). Although this is an apt description of mice it is also used to refer to all manner of small, obscure and reclusive animals and feather mites fit perfectly into this category.

Most people have never heard of feather mites which is hardly surprising. They are tiny brown arthropods which spend most of their lives flattened along the vanes of bird wing feathers where they were assumed to scavenge on feather debris and oily secretions and perhaps even rasp away at the feathers themselves. However, a remarkable study published last summer (Doña et al. 2018) examined the contents of mites’ stomachs using high-power microscopy and DNA analysis and found that their main food was fungi, and perhaps also bacteria and oil produced from the birds’ preen gland. Whether this means feather mites harm their hosts or are simply commensal remains to be seen.

Birds are assumed to acquire feather mites through physical contact with their parents while they are still in the nest, although they could also pick up mites from bumping into other birds at feeders or sharing the same dust bathing sites. Mites are quite easy to see if you are holding open a bird’s wing although with the naked eye they just look like a cluster of small dots (shown below).

We gained a whole new appreciation for these creatures when Shannon Modla of the University of Delaware kindly photographed some Gray Catbird feather mites under a light microscope. The magnified views show that they are long and thin with two pairs of legs at the front of their body and two pairs at the back (image below). The darker mites on the left and below are probably older mites with a hardened exoskeleton while the paler one on the right is probably a younger mite that has just molted.

Shannon was then able to view them under a powerful electron microscope and got some incredible images of their head as well as an egg (below).

To try to gain some insights into the biology of these enigmatic creatures we have been scoring the number of feather mites present on birds handled during the Delaware Nature Society’s Bird Banding project. Our simple questions were which bird species are most likely to have mites and whether the number of birds with mites varies according to the time of year.

Our first finding was that feather mites are quite common. We examined 448 birds belonging to 48 species and found that almost half of them (203 birds from 37 species) had mites on at least one of their wing feathers. We also found the proportion of birds with mites varies a lot between species. Over 75% of the Slate-colored Juncos, House Finches and Downy Woodpeckers that we examined had feather mites yet fewer than 15% of Ruby-crowned Kinglets, Common Yellowthroats or House Wrens had them. We also found that the proportion of birds with mites stayed quite consistent across the year with a noticeable peak in May.

This year we will be gathering more data on mites from the birds we band and then try to figure out why some birds are more likely to have mites than others, and why some have lots of mites while others have very few. Is it related to their body size perhaps, or how social they are, or maybe whether their beak is small and pointed enough to preen away the mites? So watch this space for updates on this new and fascinating DNS research project!

DNS has plenty of birding opportunities coming up soon, so sign up and enjoy the outdoors!

The Great Backyard Bird Count ~ Coverdale Farm Preserve

The Great Backyard Bird Coount: Kent County Tour ~ Abbott’s Mill Nature Center

Owls and Other Winter Raptors ~ Ashland Nature Center

 

Ian Stewart

Every fall birdwatchers throughout the eastern United States wait anxiously by their computers for an email containing this year’s Winter Finch Forecast http://jeaniron.ca/2018/wff18.htm. For almost 20 years now Ron Pittaway, a former naturalist at Algonquin Provincial Park in Ontario Canada, has been predicting whether this group of small, seed-eating birds that breed in Ontario remain there during the winter based upon how successful the cone crop was that summer. Simply put, if the trees produced a lot of seeds then the finches will have enough food to survive the winter and will stay up north, but if the cone crop was poor they will have to fly south to find food and will ‘irrupt’ into the northern United States or maybe even further south.

Remarkably, Ron’s forecast is usually correct so local birders were thrilled to read his prediction that finches would be travelling south this winter because the cone crop in Canada was poor. Sure enough, about 2 weeks ago people throughout Delaware and south-eastern Pennsylvania started seeing flocks of Purple Finches at their feeders! These look a bit like our resident House Finches but the males are raspberry-colored over their whole body while the females and immature birds are heavily streaked below and have white stripes on their face. Purple Finches are attracted to black oil sunflower seed, especially if it is piled on a horizontal platform feeder.

A flock of Purple Finches at a platform feeder

The Delaware Nature Society’s bird banding program has confirmed that this is an irruption year for Purple Finches. So far this fall we have banded no fewer than 40 of these birds, compared with just 5 in the winter of 2016 and none at all last winter.

Male House Finch (left) and Purple Finch (right) banded this fall

Now people across our region are seeing a second species of winter finch at their feeders, the Pine Siskin. This small, streaky finch has yellowy-green wing patches and a very thin beak which it uses to pry nyjer (thistle) seeds from finch socks or hanging feeders with narrow holes.

Pine Siskin feeding on ground (Photograph by Hank Davis)

The thin beak of a Pine Siskin

Whisper it quietly but this winter we may see two more highly-prized finches which usually remain far to our north. The first of these is the Redpoll, a small streaky finch with a red forehead that flocks in weedy fields and congregates at nyjer feeders. The second is the majestic Evening Grosbeak, a striking yellow, black and white version of our familiar Cardinal which is attracted to platform feeders baited with sunflower seed

All of the above winter finches readily come to bird feeders and best way to attract them to your yard is to provide a variety of seeds in different types of feeders, like hanging tubes of either black oil sunflower or nyjer coupled with platform feeders filled with sunflower seeds or millet. Try visiting Wild Birds Unlimited in Hockessin for a large selection of seed mixes and feeders.

Flock of Siskins at a hanging feeder (Photograph by Hank Davis)

Another two irruptive winter finches that are much sought after by birdwatchers are the crossbills. The Red Crossbill tends to occur in pines and the White-winged Crossbill in spruces and larches. These intriguing birds are unique in that their upper and lower beaks are ‘crossed’ and are used to prise open pine cone scales to get to the seed within. Crossbills do not usually come to seed feeders but if you want to attract them you could try pulling the old ‘salt block trick’. Apparently they are very fond of salt and can be attracted to platform feeders using chunks of the salt blocks that farmers leave out for cattle and horses!

The winter of 2018/2019 could be a memorable year for winter finches in Delaware, so be sure to take full advantage of it. The best places to search are weedy fields and stands of cone-bearing pine trees in public parks or cemeteries, but you are just as likely to see them at the feeders in your back yard or the Ashland Nature Center bird blind. And maybe consider dropping by our free bird banding sessions to see if you are lucky enough to see a winter finch up close. Bird banding takes place through November every Monday at Ashland Nature Center and every Wednesday at Bucktoe Creek Preserve near Kennett Square, 8am-11am.

 

Ian Stewart

Migration is a fascinating aspect of animal biology. Each spring and fall, millions of birds, mammals and insects fly thousands of miles to get to either their breeding or wintering grounds. Migration can be challenging to follow however, as many of these animals migrate at night and travel quickly. There are several methods scientists use to track migration but a new collaborative method has recently emerged: the Motus system.

The Bucktoe Motus tower

The Motus system is an international network of automated towers which detect any animal fitted with a special small tag within a 15km range (‘Motus’ = Latin for ‘movement’). Since each tag emits a unique signal it is possible to track the movement of individual animals as they pass by one of more towers. The great majority of animals fitted with tags are birds but tags have also been placed on bats and large insects like dragonflies or even butterflies! The Motus network allows scientists to collect data on tagged animals to help them find out how variables like weather and the animal’s age, sex, and physical condition affect the timing and speed of their movements. It also aids conservation efforts by identifying key areas where animals stop to feed and rest during migration which can then be protected.

There are over 200 towers spread across the world, most of which are in North America (see the map on the Motus homepage www.motus.org). In the summer of 2017 a team of dedicated field biologists erected a line of towers all the way across Pennsylvania. The towers are so close together that their detection ranges overlap, meaning that they would pick up every tagged animal that migrates north or south anywhere in the entire state!

Distribution of Motus towers across PA and DE

Thanks to generous funding from the Starrett Foundation and the Pennsylvania Department of Conservation and Natural Resources via the Willistown Conservation Trust, a Motus tower was erected at Bucktoe Creek Preserve near Kennett Square in August 2017 as part of this line and has been recording 24/7 ever since! In the fall of 2017 it detected 7 thrushes, 3 warblers, a woodcock and a bat, all presumably heading south for the winter. In the spring of 2018 it detected a thrush and 4 shorebirds, all likely heading north to breed.

Another remarkable feature of the Motus system is that much of the data is open-access and can be viewed by anyone with the Internet. To see what animals are being detected follow these 4 simple steps.

1. Visit the homepage at www.motus.org then scroll down to see a map of the world with a yellow dot representing each tower.

2. Zoom in to find the tower you’re interested in (e.g. Bucktoe Creek) and click the dot. A box will then open telling you the name of the tower and its location plus the contact details of the organization overseeing it. The bottom row gives the number of tags detected by that tower (if there have been any) with ‘table/timeline’ in parentheses next to it.

3. Click on ‘table’ and a new page will open with several columns including the date each tag was detected plus the ID# of that tag (in blue text) and the species it was placed on.

4. Click on the ID# to reveal the date and place where the animal was tagged, and then if you want to explore further, either click on ‘table’ in the bottom row to see a list of towers at which that bird was detected, or ‘timeline’ to see what time the animal passed by the tower and how long it stayed. My own favorite is to click on ‘map’ to show the route the animal took!

Every year more Motus towers are erected throughout North America and they are also starting to spread across other continents. The number of tagged animals is also steadily increasing and every time one is detected it adds to our understanding of animal migration. Watch this space for updates from the Bucktoe tower!