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US Fish & Wildlife Service FieldNotes

Rhode Island National Wildlife Refuge Complex Collaborates With Local Universities to Evaluate Saltmarsh Sparrow Populations

Region 5, April 12, 2013
Total number of Saltmarsh Sparrows captured on the RI NWR Complex from 2004-2012.
Total number of Saltmarsh Sparrows captured on the RI NWR Complex from 2004-2012. - Photo Credit: n/a
Fate of Saltmarsh Sparrow nests monitored on RI NWR Complex from 2008-2012.
Fate of Saltmarsh Sparrow nests monitored on RI NWR Complex from 2008-2012. - Photo Credit: n/a

The Rhode Island National Wildlife Refuge Complex (refuge) and the University of Rhode Island (URI) have partnered for the last five years in an effort to better understand the current status of and threats to Rhode Island’s saltmarshes and the wildlife that depend upon them. The Salt Marsh Integrity (SMI) project is run by the U.S. Fish and Wildlife Service and seeks to develop rapid assessment methods of evaluating the health and suitability of saltmarsh habitat through a series of bird, fish, plant and sediment accumulation surveys. The refuge has participated in the SMI study since 2009. In 2011, a group of University and non-profit scientists in the Northeast formed a research group made up of over 25 partners known as the Saltmarsh Habitat and Avian Research Program (SHARP). This group coordinates and conducts assessments of the region-wide population status of marsh birds and their habitat across the Northeast. Through bird surveys, banding and nest monitoring, the SHARP group focuses on the study of breeding marsh birds and their survival and productivity. Scientists from URI and the refuge have conducted research in cooperation with the SHARP group in 2011 and 2012 in the state of Rhode Island.

 

During the last eight years of the Saltmarsh Sparrow (SALS) research at the RI NWR Complex; varying amounts of per-year effort have been invested in the capture, banding and nest monitoring of sparrows. In 2011, we captured our highest total number of sparrows (207) and we also captured the highest number of breeding females (55). Our banding efforts have revealed a high level of breeding site fidelity in SALS; to date we have not documented any instances of sparrows breeding in a different marsh other than the one where they were originally captured during the summer. Furthermore, banded birds are often recaptured in the same area of the marsh where they were first banded. We have however, received reports for two of our birds banded during the summer in RI that were subsequently captured on the wintering grounds at southern banding locations in Virginia and South Carolina. Thus far, a total of 566 saltmarsh sparrows have been banded on the RI NWR Complex. Not surprisingly, the number of previously banded birds recaptured each year has steadily increased over the course of the study. In 2012, we had our highest total number of recaptures, with a total of 53 individuals captured that had been banded in a previous year. These recaptures included two male sparrows that were originally banded on our refuges as adults in 2007; making these two birds at least six years old. This capture and recapture data is an important source of information as to the long-term survival and life history characteristics of these birds. As part of the SHARP project, researchers from the University of Connecticut, University of Delaware and University of Maine are using this data to develop long-term survival probabilities for Saltmarsh Sparrows. These efforts will help to determine how future changes in saltmarsh habitat due to development and sea level rise could affect this sensitive bird species.

Nest monitoring has taken place on the refuge from 2008 – 2012. We found that nest success and the causes of failure can vary greatly from year to year in relation to factors such as weather and the timing of tides. For example, in 2009 we monitored the largest number of active nests (91), and found that a larger proportion of nests (47%) failed due to flooding that year. Many of these nests failed in late July when we received high levels of rainfall in conjunction with the monthly peak high tide. Near the end of the breeding season, most of the sparrows’ timing of nest initiation and the resulting timing of nest fledging is near the monthly peak tide. This is an adaptation of saltmarsh sparrows that allows them to fill an open niche by being a ground-nesting bird in a tidal marsh. Consequently, many chicks are forced to fledge when their nest floods; being too young to fly, they must run through the grass to higher ground in order to escape drowning. If the peak tide happens to coincide with a major rainfall event, as it did in July 2009, young chicks often succumb to the fast rising water and do not survive. In contrast, during the 2008 nesting season we experienced a very dry summer and found that only 27% of monitored nests failed due to flooding, nearly half of the number flooded in 2009. The effects of tides and the challenges of nesting in a saltmarsh are natural processes that saltmarsh sparrows have adapted to survive; however, the growing pressures of habitat loss and climate change present even more challenges to the bird’s survival and reproduction. The data gathered during the course of this project will give us insight as to how we can improve and protect saltmarsh habitat in order to ensure that saltmarsh sparrows and other marsh birds will always have suitable breeding areas to return to each spring.

Most recently, in 2012, we captured a total of 124 saltmarsh sparrows. We captured more birds at Sachuest NWR(44) than at Chafee NWR(39), even though the study area at Sachuest (2.9 Hectares) was less than one quarter of the size of the Chafee study area (12.8 Hectares). In 2012, we monitored the same number of active nests (14) at each refuge study site; and found 64% of monitored nests were successful at Chafee while 14% of nests were successful at Sachuest. At Chafee, all nest failures were caused by flooding; while at Sachuest, nest failures were caused by a combination of flooding, depredation and other unknown factors. Through our monitoring efforts and cooperation with investigators at local universities, we hope to determine why saltmarsh sparrows display such a strong selection preference for certain saltmarshes, even in spite of lower observed nest success. This information will help to guide the RI NWR Complex as we work with partners to manage and protect valuable saltmarsh habitat.

Contact Info: Rhonda Smith, 401-364-9124 ext. 26, rhonda_smith@fws.gov