Warren Land Trust, Inc.

Deirdre Robinson, Jim O’Neill, Steve Reinert  

With permission from the Warren Land Conservation Trust and RIDEM, the Saltmarsh Sparrow Research Initiative (SSRI) installed 26 nest arks in low-lying areas of the Jacob’s Point saltmarsh in Warren, RI. Based  upon NOAA high tide predictions and multiple years of GPS mapping of SALS nest outcomes at this 35 acre site, we selected nest locations with the highest risk for flooding. Prior to installing the arks, we determined that 100% of females returned to the nests and continued to incubate eggs and feed nestlings that had been placed within nest holders.

Methods

We designed and installed arks that would reduce nest failures by providing buoyancy during tides that would  otherwise have inundated the nests. Approximating the weight of one female and four chicks, we tested the arks by adding weights to a “dummy” nest to determine the amount of flotation required.

The nest ark consists of a coffee filter holder with (blue) flotation mats that are affixed to a wooden dowel. The  18″ dowel was inserted into a 24″ PVC pipe that was sunken into the peat, nearly flush with the marsh surface. There is minimal friction between the dowel and plastic pipe, allowing the ark to rise and fall with the tides.

Use this link to view a time-lapse video of the tidal-driven rising and falling of an arked nest: 

In all 26 arked nests, the female returned to incubate eggs, feed nestlings, and remove fecal sacs at the same frequency as pre-arking. 

We arked 26 nests at JP this season, while 45 nests were not arked, serving as controls. Based upon the finding  that arks were sitting too low in the water, we requested and received permission from RIDEM to add an additional 9 mm flotation pad for the final flooding cycle to accommodate the extra weight of a wet nest.    

Results

Fledging rate for the arked nests was 23% vs. 16% for control nests (Table 1, Fig. 1). Only one arked nest  flooded, in contrast to the nine control nests that were inundated (Table 1). Depredation rates for arked nests were higher (69%) than controls (56%), which may partially attributable to the fact that depredation historically increases later in the season, when most arks were permitted to be installed. Nest failure due to unknown causes  (e.g., abandonment, female death) was 4% for arked nests and 9% for controls (Table 1, Fig. 1).  

Table 1. 

Discussion

Small sample size cautions us to limit inferences about the success of arks in reducing SALS nest failures due to  flooding, but these preliminary findings are encouraging. The best indicator of reproductive success is the fledging rate, which was 7% higher for arked nests compared to controls. Had we been able to install arks early in the 2024 breeding season without an arbitrary cap on the number of arks that could be installed, it is likely that the percentage of successful arked nests would have significantly exceeded that of the control nests.

photo credit: Jason Jaacks

We are very grateful to Warren Land Trust for permission to study the breeding ecology of Saltmarsh Sparrows (SALS) at Jacob’s Point (JP) which has provided stakeholders (RIDEM, Save The Bay, USFWS) with baseline data that provides valuable guidance in generating management strategies.
These saltmarsh-obligate birds are heading precariously close to extinction, primarily due to flooding with secondary nest failures due to predation. On this 7 year composite map (below) that Jim O’Neill created, waterfall icons represent flooded nests; solid dots are depredated nests; bird icons reveal successful nests.

Based upon this data, we will determine where to lift nests that are at the highest risk for flooding in 2024, using coffee filters as nest protectors which are mounted upon stakes that will be raised above the flooding threshold.

It has been a busy “off season” while writing grant applications, submitting papers for publication, measuring museum specimens of SALS to compare to modern birds, securing funding for student interns, and presenting findings at Audubon’s annual Conservation Symposium.

Raised nest with protective coffee filter. photo credit: Deirdre Robinson

The sparrows returned to JP during the first week in May, when we began the search for cryptic nests and test the hypothesis that nest lifting can postpone their date with extinction. If this novel intervention is successful at JP, we hope that our protocol will be scalable to saltmarshes from VA to ME, where Saltmarsh Sparrows exclusively breed.

As E.O. Wilson famously said, “Conservation biology is a discipline with a deadline.”

Thanks to the Warren Land Trust for allowing us to postpone the extinction deadline for this valuable bird who is an indicator species for the health of the saltmarsh ecosystem.

-Deirdre Robinson, SSRI Co-Director

map created by Jim O’Neill

Join us for this Free Event in celebration of spring!

Butch will share his photographs and discuss his experiences and approach to bird photography. There will be an optional nature walk after the talk, weather permitting.

Over the past 50 years, Butch has combined his passions for birds and photography to share compelling and unique images of nature. His images have been published in Yankee Magazine, East Bay Newspapers, The Providence Journal, The Boston Globe, The Audubon Society of RI’s quarterly magazine, and yearly calendars, The National Wildlife Federation’s Christmas catalog as a Christmas card, and The Academy of Natural Science’s Journal of Raptor Research Quarterly Book, and more.

March 24, 1:00 – 2:30 PM
Audubon Nature Center, Bristol, RI

For more information, see the flyer.