Written on: May 18th, 2020 in Wetland Animals
Guest Student Writer: Elisa Elizondo , Ph.D. Student, University of Delaware
Colloquially known as marsh hens, the Clapper Rail (Rallus crepitans) is a vocal inhabitant of saltmarshes across the eastern coast of the United States and down into the Caribbean. Many of the first in-depth observations of Clapper Rail occurred in the mid-Atlantic, and in Delaware, Brooke Meanley documented much of their ecology. The northern Clapper Rail populations, including Delaware, have been declining based on extensive survey work conducted by the Saltmarsh Habitat Avian Research Program (SHARP).
Rails are typically secretive in nature, making their populations very difficult to monitor. One important measure of population health is nest survival, as the rate at which nests survive determines the number of offspring that can be produced to join the population in the following year.
Beginning in 2018, research conducted through the University of Delaware has been monitoring Clapper Rail nests in Delaware. Locating the nests can be tricky and is accomplished by searching on foot and using thermal imaging taken from a drone. Once a nest is located, the eggs can be floated in a container with freshwater to help determine their age. As the eggs develop, gas builds up within the egg ultimately causing it to float. When the eggs are close to hatching, they will float right to the top!
Often in the early stages of the nest, the adult rails are not spotted. When the eggs initiate hatching, however, the adults are at their most defensive. Both the male and female Clapper Rail incubate the nest and tend to the chicks. They employ various techniques to protect their nests including loud vocalizations, using their wings to appear larger, or feigning injury in the hopes of drawing off the predator. The chicks are ready to run into the marsh 1-2 hours after hatching, but currently there is no information on how many of those chicks make it to adulthood.
In order to learn more about adult Clapper Rail survival and habitat use, the University of Delaware research crew is deploying GPS tags. These tags can be programmed to take GPS points throughout the day. Those data are then either sent to a satellite then downloaded online or downloaded manually by getting close enough to a bird to transmit the data to a handheld device (the download method varies by tag model).
Each tag can provide hundreds of locations that we can use to determine their territories. This helps us to determine what areas each individual bird is using and the overall types of habitat the birds seem to prefer. The satellite tags can continue to transmit for several years to help identify where the birds migrate to as well.
These data can sometimes yield surprising new information; in 2019 we discovered a tagged male bird with two nests ~5 m (approximately 16 feet) apart within his home range! Blood samples were drawn from both the adult and several chicks from the nests so that paternity can be evaluated in the lab.
There are 8 subspecies of Clapper Rail, and only the Northern Clapper Rail (R. c. crepitans) migrates. Here in Delaware, hunting band records from the 1950s and recent satellite data from birds tagged in Delaware indicate that Clapper Rail from Delaware winter in South Carolina and surrounding states. Understanding the population connectivity, or the degree to which populations interbreed, is important in determining population trends and areas of high conservation concern.
To determine the relationship of Clapper Rail in Delaware to other regions, blood samples are currently being collected from all tagged birds. Through collaborations with other state agencies and academic partners, additional samples will be collected from across the U.S. range of these subspecies to assess population connectivity using Next Generation Sequencing techniques. Given that Northern Clapper Rail populations seem to be in decline, it is increasingly important for us to understand how their populations relate to non-migratory subspecies.
This research is made possible by many funding resources, including the Delaware Department of Natural Resources and Environmental Control, the Delaware Ornithological Society, U.S. Fish and Wildlife Services, and the University of Delaware.
Written on: May 15th, 2020 in Beneficial Use
The Shoreline & Waterway Section (SWMS) manages 27 channels in all 3 counties of the State of Delaware. SWMS collaborates with WMAP to find creative and beneficial ways to use sediment dredged
Written on: May 13th, 2020 in Outreach
Delaware is known for its ability to tackle complex problems by bringing its residents together to work out solutions. Among this year’s problems: planning how the state will respond to climate change.
At first glance, an oyster appears to be little more than, well, a bit of goo inside a rock. But actually, the humble oyster is an environmental warrior with an impressive bag of tricks up its sleeve, and it serves as a keystone species upon which depends the health of a marine ecosystem and the surrounding marsh.
Guest writer: Kelly Valencik, DNREC Delaware Coastal Programs Communities Seeing Shifts in Mother Nature Many communities throughout our state have already seen changes as a result of climate change- from shifting rainfall and storm patterns, to increased drought, to flooding from sea level rise. These consequences of the warming earth and ocean temperatures as a […]
Written on: March 6th, 2020 in Wetland Assessments
In tidal marshes, accurate representation of marsh elevation or height is critical for understanding sea-level rise, tidal inundation, and storm surge. Small changes in marsh elevation can significantly change the water movement (hydrology), plants (vegetation), and habitat. Our study aims to look at and correct a remote sensing method known as light detection and ranging (LiDAR), in order to provide accurate elevation data to scientists and coastal managers in Delaware.
Written on: March 5th, 2020 in Outreach
Man-eating plants are a thing of sci-fi movies, they will send vines out to capture you or leap at you and consume you but back in the real-world carnivorous plants are a real thing. The world consists of more then 600 known species of carnivorous plants that use varying tactics to capture and digest their prey.
Although it is happening around the world, there are some spots that are being affected more than others. The Mid-Atlantic Coast—including Delaware—is experiencing one of the highest rates of sea level rise in the U.S, second only to the Gulf Coast.
Written on: December 11th, 2019 in Outreach
You don’t have to own 20 acres of flooded fields to make a difference! There are many common wetland stressors that are not an easy fix, such as ditching and channel straightening but addressing invasive plants is a great place to start.
Written on: December 10th, 2019 in Wetland Restorations
Riparian buffers are planted areas specifically next to waterways, such as streams, ponds, wetlands, and rivers. These areas are extremely important to keeping our waters healthy. They do so by filtering and trapping nutrients and sediment out of waters before they enter our local waterways.