WICOMICO'S MIGRATORY BIRDS
Migratory birds are an important aspect of Wicomico's forest communities. However, the changing climate is altering the behaviors of many species. For instance, variable temperatures are changing spring arrival times, throwing birds out of sync with the budding of their food sources. Meanwhile, intruding saltwater causes tree mortality and consequently reduces the amount of habitat available for nesting.
Migratory birds are an important aspect of Wicomico's forest communities. However, the changing climate is altering the behaviors of many species. For instance, variable temperatures are changing spring arrival times, throwing birds out of sync with the budding of their food sources. Meanwhile, intruding saltwater causes tree mortality and consequently reduces the amount of habitat available for nesting.
VARIABLE CLIMATE AND MIGRATORY BIRDS
Wicomico County is the summer home for many migratory birds that overwinter in Central and South America. In fact, we have the highest concentration of migratory songbird nesting sites in the entire state of Maryland. However, there will be subtle shifts in these birds' migratory patterns as the temperature becomes warmer and more variable with climate change. According to the Nature Conservancy, some species are already arriving a bit earlier or later than they did as little as thirty years ago; and although this may not sound like a big deal, many of these bird species are specifically tuned in to certain insect hatches or berry-producing shrubs. As divergences arise between insect hatches and the time of the migratory birds' arrival, birds will either have to adapt to a new food source, migrate out of the area, or perish [1].
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"Spring Budburst in a Changing Climate"
Richard B. Primack, Amanda S. Gallinat For more information about how a warming climate is throwing off the timing of spring, visit The American Scientist. This article (button above) uses Henry David Thoreau's 160 year old field notes to compare the timing of spring activities between then and now. Scientists then describe the implications of climate warming on ecosystem health [9]. |
The upland mixed forests of Wicomico County consist of pines and hardwoods that provide crucial habitats for species like the Cerulean Warbler, Wood Thrush, Kentucky Warbler, Acadian flycatch, Worm-eating Warbler, Eastern Wood-pewee, Louisiana Waterthrush, Scarlet Tanagers, and Phoebes. Most of these birds require a specific minimum area of continuous forest in order to survive. For instance, the Cerulean Warbler needs around 1,000 acres of upland forest while the Swainson's Warbler requires at least 400 acres of shaded forest habitat in either deciduous forests or swamp forests near the Pocomoke. Pine forests, which have become the most abundant upland forest type in Wicomico County, also provide summer homes for species adapted to grass and shrub understories under open pine canopies. These species include the Blue-winged Warbler, Brown-headed Nuthatch, Northern Bobwhite, Carolina Chickadee, and Gray Catbird [2].
VARIABLE PRECIPITATION PATTERNS AND THE AMERICAN WOODCOCK
The American Woodcock is considered a migratory bird of special concern by the Maryland Department of Natural Resources. Its range spans the dense, upland forests of the eastern United States and Canada and it can be found throughout the state of Maryland in the spring and summertime. Chesapeake Forest lands serve as breeding and nesting areas, and as migration corridors for these species as they migrate through New Jersey, across the Delaware Bay, and continue south along the eastern shore of Virginia. Most Maryland Woodcock migrate to the southeastern United States during the winter, but some northern populations choose to overwinter in Wicomico County and other locations on the Eastern Shore of Maryland. Unfortunately, the US Fish and Wildlife Service has documented that Woodcock numbers have been declining at an average rate of 1.9% per year since 1968. Most biologists presume that habitat alterations and losses of second growth forests to development have caused this decline [3].
Climate change could further distress Woodcock populations. These birds are sensitive to changes in precipitation because they have a very narrow dietary range, feeding mainly on earthworms found in the rich humus layers of moist soils. The Woodcock requires consistent moist soil for both nesting and foraging for food, but as precipitation patterns change, spilling higher volumes of water during more infrequent rainfall events, habitat will be further diminished. Earthworms cannot exist in dry soils, so the Woodcock will struggle to find food during long dry-spells, and even when it does rain, it will fall with such intensity that it is more likely to wash the humus soil layers away than to seep gradually into the ground and rejuvenate life [4].
SALTWATER INTRUSION AND MIGRATORY BIRDS
In Wicomico County, saltwater intrusion is becoming a dominant force for deforestation, along side of land development, fires, disease, and invasive species. It results from climate change because as sea level rises, saltwater is pushed farther and farther upstream, spilling out over the land to inundate freshwater soils and underground aquifers. Most tree species cannot tolerate high levels of salts in the soil because, by way of osmosis, freshwater is literally sucked out of their roots and the plants die of thirst. As a result, large expanses of forests die, leaving stands of dead trees known as "ghost forests" [5]. For instance, as you drive towards Crisfield or Deal Island, you can see these stands of dead hardwood trees. They have perished as a result of salt water intrusion occurring slowly as sea level rises or from significant storm-surge events [6]. Eventually, these once-forested lands will turn to marsh and then, ultimately, to open water. In July of 2016, the Department of Agriculture aerially examined the Lower Eastern Shore for signs of saltwater intrusion. They determined that 2,922 acres of land had been affected in Wicomico County alone [7]. As saltwater intrusion reduces available forest land along the Wicomico, Nanticoke, and Pocomoke rivers, and as forests become ever more fragmented due to human development interests, migratory birds will no longer have the opportunity to nest in large expanses of forest [1].
Furthermore, these birds are largely tuned in to specific insect hatches or berries, but with the intruding saltwater, shortages of these resources will likely disrupt food webs and alter ecosystem composition. Joe Fehrer also noted that trees and herbaceous plant species are moving northward, and soon the diverse biological communities of the Eastern Shore will follow, leaving Wicomico County to an uncertain biological future. The Nature Conservancy is especially concerned with these changes as much of their work concerns the well-being of migratory bird species. Moreover, recreational birdwatching is ingrained into the Eastern Shore culture; thus, it would be lamentable to see it disintegrate with the permanent emigration of these unique species [1].
Furthermore, these birds are largely tuned in to specific insect hatches or berries, but with the intruding saltwater, shortages of these resources will likely disrupt food webs and alter ecosystem composition. Joe Fehrer also noted that trees and herbaceous plant species are moving northward, and soon the diverse biological communities of the Eastern Shore will follow, leaving Wicomico County to an uncertain biological future. The Nature Conservancy is especially concerned with these changes as much of their work concerns the well-being of migratory bird species. Moreover, recreational birdwatching is ingrained into the Eastern Shore culture; thus, it would be lamentable to see it disintegrate with the permanent emigration of these unique species [1].
Wicomico's Migratory Songbirds
The button below will take you to ebird.org, where you will find a list of resident and migratory bird species found in Wicomico County. Two hundred and ninety-seven species are featured and the charts display the dates they have been sighted. By clicking on the map next to their name, you can view the exact location where these birds have been spotted and consequently can visit these places in attempt to spot them for yourselves! Follow the charted arrival and departure patterns for each migratory species. By changing the date range at the top of the page, you can see how early or late migratory birds have been spotted over the years. Can you detect a shift? Keep an eye on the page, it will be interesting to see how these sightings fluctuate in the future with shifting seasonal weather [8]!
Click to return to Forests or learn more about its species!
References
- Personal communication, Joe Fehrer, Coastal and Lower Shore Project Manager for The Nature Conservancy, 4 April 2018, Furnace Town Visitor Center.
- Maryland Forest Service. Maryland Department of Natural Resources. (2007). Sustainable forest management plan for Chesapeake Forest Lands: Sustainable forests for people and the bay (Report No. 11). Sustainable Forestry Initiative. Retrieved from http://dnr.maryland.gov/forests/Documents/chesapeake/CF-SFMP_2018.pdf
- Maryland Department of Natural Resources. (n.d.). Maryland Birds: Woodcock (Scolopax minor). Retrieved from http://dnr.maryland.gov/wildlife/Pages/plants_wildlife/woodcock.aspx
- Ecology and vulnerability: American Woodcock. (2017). Retrieved from https://climateactiontool.org/species/american-woodcock
- Upton, J. (2016). Ghost forests are eerie evidence of rising seas. Retrieved from https://grist.org/article/ghost-forests-are-eerie-evidence-of-rising-seas/
- Personal conversation, Tami Ransom, Environmental Studies Professor at Salisbury University, 9 April 2018, email interview.
- U.S. Department of Agriculture. (2016). Maryland Forest Health Highlights. Retrieved from https://fhm.fs.fed.us/fhh/fhh_16/MD_FHH_2016.pdf
- Bird Observations. (2018). Retrieved from https://ebird.org/barchart?byr=2000&eyr=2018&bmo=1&emo=12&r=US-MD-045
- Primack, R. B. & Gallinat, A. S. (2016). Spring budburst in a changing climage. Retrieved from https://www.americanscientist.org/article/spring-budburst-in-a-changing-climate