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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!

By Ian Stewart

The buzz around this year’s Native Plant Sale is building to fever pitch! Our plant sale comes at the perfect time as we have finally emerged from the frigid gloom of an unusually long cold winter to find colorful wildflowers emerging all across the state. These ‘spring ephemerals’ are so-named because they only flower for a fairly short time since they start losing the sunlight once the trees leaf out.

We are fortunate to have a lot of fairly common attractive native plants in Delaware, and sometimes these get taken for granted. This is a pity, as several have some surprises in store if you look at them closely. Trout Lilies are a perennial often found growing in clumps which get their name because their mottled leaves resemble the sides of a Brook Trout, a freshwater fish. However, they take between 4 and 7 years to mature so the great majority of the lilies you see don’t produce a flower and have just a single leaf (top photo). Only the older, flowering plants have two leaves (second top). The beautiful nodding Lily flowers are harder to find but tend to occur in small colonies which are often visited by insects (bottom photos).

The familiar Mayapple has a similar subtlety. This distinctive umbrella-shaped wildflower of shady forest floors is often found in dense clusters of what look like identical plants, but if you look closely you will see that some have a forked, Y-shaped stem whereas most have just a single stem (below). Only the Y-shaped stems produce a flower then later the apple-like fruit. Mayapples are actually misnamed, as in May they still only have the white flower, which is found in the base of the fork. The hanging ‘apple’ doesn’t appear until later in the summer, and despite the name, is not pleasant to eat and may even be poisonous so we do not recommend that you try it.

Delaware is blessed with a kaleidoscope of beautiful native wildflowers in our area and below are a few of my favorites (from top, Virginia Bluebell, Cardinal Flower, Great Lobelia, Butterfly Weed).

These beautiful wildflowers are available at a reasonable price at the Native Plant Sale so if you want to able to observe these natural wonders in your own back yard just come on by. As well as their visual appeal they are popular with beneficial pollinator insects like bees and butterflies, so now you can have an idyllic native garden and help nature at the same time!

The Plant Sale is held at Coverdale Farm Preserve (543 Way Rd, Greenville, Delaware) Thursday May 3rdand Friday May 4th from 3pm to 7pm (member days) and Saturday May 5th (10am – 4pm) and Sunday May 6th (11am – 3pm) (open to public). Free admission if you just want to come and browse! Credit cards, checks and cash accepted. Click on the link below for more details.

http://www.delawarenaturesociety.org/NativePlantSale#.WuijZi7wa7Q

Ian Stewart

The global Great Backyard Bird Count took place from February 16th to the 19th and was a huge success. Despite its misleading name, participants counted every bird they saw no matter how far they were from home, with more than 6,000 bird species recorded across the world from over 160,000 checklists! Delaware Nature Society played its part with 10 people joining Joe Sebastiani and Matt Babbitt on a bird-filled tour of Port Penn Wetlands, the Aquatic Resources Education Center, Bombay Hook NWR, and Port Mahon Road, finding over 50 species in the process including a rare Tree Swallow.

Although the global comparisons are fun, what’s really fascinating is to sift through the species and checklist totals from each US state (https://ebird.org/gbbc/region/US/regions?yr=cur&m=). The top 3 in terms of species seen were California (370), Texas (358) and Florida (288) with Delaware coming in 24th with a very respectable 145 species. The top 3 in terms of checklists submitted were again California and Texas (8,113 and 6,389 respectively) and New York (6,154) with Delaware coming in 37th with a decent 709.

DNS Members enjoying a duck extravaganza at Port Penn

But wait, I hear you cry! Surely this is unfair! California, Texas and Florida are all large states with extensive oceanic coastlines and inland water bodies and because of their southern latitude have resident tropical birds that we can only dream of. Furthermore, large parts of these states have mild or even warm winters so their birdlife gets supplemented by migrants that summered much further north. California, Texas and New York all contain huge numbers of people which presumably translates to lots of birders so it’s hardly a surprise that these 3 states produce the largest numbers of checklists.

I decided to see how Delaware fared during the GBBC once you take into account our small population (ranked 45th in the nation) and size (ranked just 49th!). To do this, I simply divided the number of species seen and checklists submitted from each state by their population (in millions) and size (total land area).

Sure enough, once you control for population size (as a crude estimate of the number of birders) we jump to second in the nation!

State Species per 1M persons
1. Alaska 158
2. Delaware 152
3. Wyoming 147
50. New York 9

And when you take into account our small size, Delaware recorded the second highest number of species in the country.

State Species per 1000 square miles
1. Rhode Island 74
2. Delaware 58
3. Connecticut 24
50. Alaska 0.2

The number of checklists is also an interesting statistic although obviously they aren’t all created equal. One checklist may summarize birds seen by a large group of experienced birders during an intense 6-hour search of a large, rural, mixed-habitat wildlife preserve while another could be birds seen at an urban backyard feeder by a relative novice during a 15 minute coffee break. Still, when you account for population size, we generated the third highest number of checklists in America.

State Checklists per 1M persons
1. Vermont 1503
2. Maine 918
3. Delaware 745
50. Nevada 119

And when you take into account our small size, Delaware produced the third highest number of checklists in the US!

State Checklists per 1000 square miles
1. New Jersey 325
2. Connecticut 292
3. Delaware 285
50. Alaska 1

Admittedly, trying to boil down differences between state bird lists based on just their size or population is simplistic. The dramatic differences between states in their habitat diversity and latitude and longitude means you are never comparing like with like. For example, birders in coastal states see large numbers of seabirds and shorebirds which are hard to find further inland. Freshwater lakes or marshes in the south will have more waterbirds than those in the frozen north. Plus, even though some states are huge a large proportion of their area is inhabited by very few people let alone birders, and so only a small proportion receives coverage. I’m sure there are many more bird-related differences between states you can think of yourself.

But it’s these exact same caveats that make Delaware such a fantastic place to live if you like birds! Because we are mid-latitude we get a sprinkling of unusual birds from further north plus a few rarities from further south. We have freshwater, seawater, estuaries, lakes and ponds, marshes, plowed fields and pasture, pine woods, deciduous woods, urban habitats, suburbs and a big open sky. This diversity of habitats was probably the main reason the Delaware GBBC produced such an amazing diversity of birds despite our small population and size. To all the Delaware birders who contributed to the GBBC (and you know who you are) I say well done! We’re in the Top 3!

If you want to continue to enjoy birds, why not come along on these upcoming DNS events and bird walks?

Dinner and Owls

February 28
5:30pm
$20/$25
Coverdale Farm

Led by Jim White and Courtney McKinley. Get close up looks at the rare Long-eared Owl, and search for other owls like Screech and Great Horned Owls. Dinner and an owl presentation are included too!

Frogs and Woodcocks

March 28
5:30pm
$15/$20
Coverdale Farm

Led by Jim White.Take a walk in the evening to find chorusing frogs and see the amazing display of the American Woodcock.

Tuesday Bird Walks (April/May)

8am, Middle Run Natural Area
Free, just meet in the parking lot

Thursday Bird Walks (April/May)

8am,Ashland Nature Center
Free, just meet in the parking lot

 

Autumn among the beeches

Ian Stewart

If life is getting you down or you’re feeling particularly stressed why not take a gentle afternoon stroll through a beech wood? Walking through a beech wood in the fall is a serene experience that will instantly melt away your troubles. And if you look closely, the beeches have a few surprises in store…..

The American Beech (Fagus grandifolia) is a fairly common tree across almost all of the eastern United States and is easily recognized by its smooth, pale gray bark and its above-ground ‘knees’ formed by the tops of its shallow roots. We have several stands of old, large beech trees around our DNS sites because early settlers tended to leave them alone as they often grow on hillsides which aren’t attractive sites for home building or farming, and also because their hard wood is difficult to cut.

At this time of year the ground beneath a beech wood is littered with a carpet of their golden leaves and if you wait long enough you will see a variety of mammals and birds rustling though them in search of fallen beech nuts. These distinctive triangular nuts emerge in pairs from their tough, furry husks when ripe and are beloved by deer, squirrels and Blue Jays and were apparently the favored food of the extinct Passenger Pigeon. Beech nuts are edible to humans once they have been peeled although they are apparently bitter and may even be toxic in large quantities so we do not recommend that you eat them.

Part of the reason beech woods are so attractive to walk through is that they are remarkably open, with very little understory of bushes or shrubs to navigate through. This is because beech trees are thought to be allelopathic, meaning they exude a chemical into the soil around them which inhibits the growth of other plants. Sometimes the only plant you see growing near a beech tree is a ring of ‘root sprouts’ growing around its trunk, which is a direct way through which beech trees spread in addition to their nuts.

Still, despite their placid outward appearance beech woods are tinged with intrigue. If you get down on your hands and knees you will notice that most of the trees have a circle of mysterious brown weedy stems around their base. These are known as Beechdrops (Epifagus virginiana) and are among a handful of plants that don’t photosynthesize but instead live parasitically by burrowing into the roots of beech trees and extracting their nutrients.

So please take the time to explore a beech wood this fall, but be sure to appreciate the small struggles going on underneath these giant trees!