Report on Barn Swallows in Hadley Now Available

The final report describing “Barn Swallow Nesting Biology at Bri Mar Stable, Hadley, Massachusetts During 2019” is available here. The report, written by Mass Audubon’s Director of Bird Conservation, Jon Atwood, as well as collaborators with the U.S. Fish and Wildlife Service, describes the scientific context and behavioral ecology of Barn Swallows nesting at the Fort River Division of the Silvio O. Conte National Fish and Wildlife Refuge.

In Mass Audubon’s formal response to the proposed demolition of an abandoned horse stable that is used by a large colony of nesting Barn Swallows, we wrote “If the barn does indeed need to be demolished in the near future, Mass Audubon supports the Refuge’s proposed action, Alternative A – Phased Closure of Stable and Delayed Demolition. We encourage the U.S. Fish and Wildlife Service to use the opportunities available under Alternative A to study methods that can be used to promote colony relocation on private and public lands. We also support monitoring of Barn Swallows on and around the site during the phased closure process. Mass Audubon’s bird conservation staff are willing to advise and support the refuge staff in those efforts.”  This report is the result of this promised research effort.

The report provides useful data that is relevant to decisions regarding future plans of the refuge. There is no doubt that this site hosts a large colony of this declining species. However, multiple authors have pointed out that factors other than availability of nest sites are most likely responsible for the species’ regional population declines, and have even noted that small colonies often have higher reproductive success than large nesting groups. In 2019 we had good success in attracting swallows to nest in an adjacent structure where they can be protected in the future. And, we also discovered other nearby Barn Swallow colonies, including at least one site that is probably comparable in size to the colony at Bri Mar Stable.

We’ll keep you posted as we learn more about this ongoing issue.

Barn Swallows nested on electrical boxes in structures nearby the Bri Mar Stable. Photo by Ainsley Brosnan-Smith.

Errata: After we published the final report about Barn Swallow nesting biology at Bri Mar Stable, we discovered information about past nesting activity within the Boat House. These sentences, found in the Abstract and Results sections of the report, have been corrected.

3 thoughts on “Report on Barn Swallows in Hadley Now Available

  1. Nancy Goodman

    Yes, facts do matter. That’s why over the past year, Save Our Swallows has sent FWS and MA Audubon, expert comments on the Bri-Mar Environmental Assessment from national and international Barn Swallow researchers, as well as peer-reviewed scientific articles – all of which contain myriad facts supporting our rebuttal posted on this blog entry. Perhaps FWS and MA Audubon should revisit those documents.

    Reply
  2. Jon Atwood

    Save Our Swallows makes a number of comments that we have tried to respond to below (listed as numbered bullets). First and foremost, however, we wish to recognize that Mass Audubon and swallow advocates are all on the same side – we want to stabilize and possibly even increase Barn Swallows populations in our region! The question – in the following discussion – is how best to accomplish this goal.

    1. “The Audubon report claims that ‘there is little evidence that loss of nesting sites has an important influence on regional population levels.'”

    This is an important note. Additional information, prepared by scientists not affiliated with Mass Audubon, state: Brown and Brown (2019) concluded that “many populations [of Barn Swallows] are probably not regulated by nest-site availability,” citing Holroyd’s (1975) observation that local numbers of breeding pairs often remain stable even when the availability of suitable nesting sites increases. Similarly, Robinson et al. (2003) found, in a study which covered all of Britain, that “there was little evidence of an association between change in the [availability of] nest-sites . . . and change in Swallow numbers.”

    Note also that the Mass Audubon report does not promote removal of the Bri Mar Stable. Since April, our only official position has been: “If the barn does indeed need to be demolished in the near future, Mass Audubon supports the Refuge’s proposed action, Alternative A—Phased Closure of Stable and Delayed Demolition. We encourage the US Fish and Wildlife Service to use the opportunities under Alternative A to study methods that be used to promote colony relocation on private and public lands. We also support monitoring of Barn Swallows on and around the site during the phased closure process. Mass Audubon’s bird conservation staff are willing to advise and support the refuge staff in those efforts.” Mass Audubon will always do our best to take stances that we feel can be backed up by science.

    2. “The significance of the ‘so called Boat Room’ in 2019 is misrepresented. U.S. Fish & Wildlife is trying to attract Barn Swallows that nest in the Stable to a 40 X 40 ft ‘so-called Boat Room,’ which is attached to a riding arena that is attached to the Stable. The Audubon report declines to include past information on number of nesting pairs in the boat room for the years it was monitored by volunteers. Their paper reports 6 pairs used the boat room in 2019 as a new development. In 2016, 6 pairs used the boat room as well, and this was, and still is, not particularly significant; it is a mere fraction of the number of pairs nesting in the Stable. ”

    This is a correct criticism. The Boat Room apparently was used by nesting swallows in previous years, but we were not made aware of these observations until after our report was published.

    3. “The uniqueness of the Stable as know largest colony in area is minimized. ‘Notably, at 1 location, involving 3 closely-spaced buildings, a total of 93 well-developed nest sites were found on 26 June.’ First, three buildings is not the same as one. As far as we know, there is still no colony of comparable size nesting in the vicinity. Second, the observation of a total of 93 well-developed nest sites does not mean active nesting.”

    The report was quite cautious in describing the number of pairs present at these sites: “… these preliminary data at least suggest that this colony may be similar in size, or possibly even larger, than the nesting group at Bri Mar Stable.” More work is certainly warranted, which we hope to pursue in 2020.

    It is also interesting that in the case of Barn Swallows, other researchers have basically suggested that larger is not necessarily better. As stated in our report, Brown and Brown (2019) suggested that under historic, natural conditions, most Barn Swallows probably nested individually or in small groups; these authors considered a nesting colony of >35 nests to be unusual, and noted that “studies of coloniality in Barn Swallows have revealed few advantages of group living.” In Denmark, Møller (1987) found that the costs of coloniality were more obvious than the benefits: birds nesting in larger colonies found less food, spent more time guarding their mates and nests, experienced more extra-pair copulations, more ectoparasitism, more predation, more infanticide, and more brood parasitism. Similarly, in New York, Shields and Crook (1987) found that fewer young fledged from nests in larger groups than from solitary nests or nests in small groups, suggesting a net reproductive cost to coloniality.

    4. “The predicted use of ‘so called Boat House’ by potentially displaced swallows is guesswork. ‘The Boat House, approx. 40 ft X 40 ft in size, will be maintained in future years for equipment storage, and will remain available to nesting Barn Swallows and other aerial insectivores. If this building were to eventually be occupied at a density comparable to what was observed during 2019 in either end of Bri Mar Stable, approx. 10 pairs might be predicted to nest in the structure; using average densities calculated at the finer scale of the 12 ft X 12 ft grid cells, the Boat House might support approx. 32 pairs of swallows.’ This scaling exercise does not incorporate important factors beyond observed nesting site density, and is overzealous for a few reasons. First is our lack of understanding of the physical features that drive habitat selection within buildings. (1) According to work done in Canada, most importantly, the smaller boat house will have dramatically different the thermal properties than the stable. It will likely have increased airflow and much cooler temperatures. (2) Structures set up elsewhere to provide Barn Swallow nesting sites have had limited success. (3) Larger structures may provide important roosting areas and flyways; this is especially true when young are fledging and dozens of swallows are going into and out of a nesting structure.

    We have gone to some effort to provide supportive literature citations to claims made in our report. We would be happy to review published papers that describe the importance of a barn’s thermal properties or ‘flyways’ within a structure. Barn Swallows are an extremely well-studied species, worldwide, and there are probably hundreds of published studies that we are unaware of.

    5. “The Audubon Report only mentions two alternatives proposed in the Bri-Mar Environmental Assessment (EA). ‘The USFWS has evaluated two alternatives that would result in the demolition and removal of the stable by the close of Fiscal Year 2020, ending on 30 September 2020.’ There are three alternatives in the EA, including letting the Stable stand and decay in place.”

    Correct. Our report intentionally is not meant to evaluate the various management options that have been presented by the USFWS. We set out to produce an objective review of available science and ecological information that has been accepted by the scientific community, and that is all that this report includes.

    6. “The Audubon Report was co-authored by two FWS employees. Two Report authors are in conflict of interest as FWS officials, one of them the chief proponent for the project being studied.”

    Jon Atwood’s 2 co-authors, both employed by the USFWS, were valued collaborators in this research, and are rightly included as co-authors. Mass Audubon received no financial support for our participation in this research.

    Reply
  3. Save Our Swallows

    Save Our Swallows Rebuttal

    Habitat argument illogical; importance of thriving Barn Swallow colonies is minimized.
    The Audubon report claims that “there is little evidence that loss of nesting sites has an important influence on regional population levels.”
    Factors other than limited nesting habitat are implicated in Barn Swallow population declines, which makes saving the habitat of thriving colonies all the more critical. Barn Swallows are declining and disappearing from traditional nesting sites for unknown reasons; implicated are agricultural intensification, pesticides, climate change, and threats on migration routes and wintering areas. These factors are difficult to address, requiring major shifts in policy, international cooperation, and some may not be possible to reverse. The one tangible factor we CAN address is habitat. We should save the prime nesting habitat of thriving Barn Swallow colonies while we try to understand and address causes of declines.

    The significance of the “so called Boat Room” in 2019 is misrepresented.
    U.S. Fish & Wildlife is trying to attract Barn Swallows that nest in the Stable to a 40 X 40 ft “so-called Boat Room,” which is attached to a riding arena that is attached to the Stable. The Audubon report declines to include past information on number of nesting pairs in the boat room for the years it was monitored by volunteers. Their paper reports 6 pairs used the boat room in 2019 as a new development. In 2016, 6 pairs used the boat room as well, and this was, and still is, not particularly significant; it is a mere fraction of the number of pairs nesting in the Stable.

    The uniqueness of Fort River Refuge as protected land is minimized.
    “At least ten structures were found within 4 miles of Bri Mar Stable in 2019 that appeared to be potential nesting sites, although a more thorough survey is certainly warranted.”
    These structures are privately owned. Barn Swallows nest only at the mercy of the owners of the structures they are nesting in. These structures are not on a National Wildlife Refuge; there is no guarantee that that owners do or will continue to welcome them, and even if they did, will the next generation do so? There is no guarantee the surrounding area will remain suitable for Barn Swallows, and the buildings could be sold, boarded up, or razed.

    The uniqueness of the Stable as know largest colony in area is minimized.
    “Notably, at 1 location, involving 3 closely-spaced buildings, a total of 93 well-developed nest sites were found on 26 June.”
    First, three buildings is not the same as one. As far as we know, there is still no colony of comparable size nesting in the vicinity. Second, the observation of a total of 93 well-developed nest sites does not mean active nesting.

    The predicted use of “so called Boat House” by potentially displaced swallows is guesswork.
    “The Boat House, approx. 40 ft X 40 ft in size, will be maintained in future years for equipment storage, and will remain available to nesting Barn Swallows and other aerial insectivores. If this building were to eventually be occupied at a density comparable to what was observed during 2019 in either end of Bri Mar Stable, approx. 10 pairs might be predicted to nest in the structure; using average densities calculated at the finer scale of the 12 ft X 12 ft grid cells, the Boat House might support approx. 32 pairs of swallows.”
    This scaling exercise does not incorporate important factors beyond observed nesting site density, and is overzealous for a few reasons. First is our lack of understanding of the physical features that drive habitat selection within buildings. (1) According to work done in Canada, most importantly, the smaller boat house will have dramatically different the thermal properties than the stable. It will likely have increased airflow and much cooler temperatures. (2) Structures set up elsewhere to provide Barn Swallow nesting sites have had limited success. (3) Larger structures may provide important roosting areas and flyways; this is especially true when young are fledging and dozens of swallows are going into and out of a nesting structure.

    Breeding Bird Survey (BBS) trend maps tell different stories depending on the time frame used.
    The Audubon report used the range of 1966-2017 for their trend map. The map of Barn Swallow BBS trends from 1993-2017 shows that population declines have become steeper more recently—and that for this time period, Barn Swallows are declining across most of their North American breeding range. (North American Barn Swallow population trends, USGS Breeding Bird Survey data, 1993-2017. https://www.mbr-pwrc.usgs.gov. Data:expanded– States/Prov – Years:1993-2017 – Barn Swallow [Hirundo rustica])

    The Audubon Report only mentions two alternatives proposed in the Bri-Mar Environmental Assessment (EA).
    “The USFWS has evaluated two alternatives that would result in the demolition and removal of the stable by the close of Fiscal Year 2020, ending on 30 September 2020.”
    There are three alternatives in the EA, including letting the Stable stand and decay in place.

    The Audubon Report admits illegal nest moving after NEPA EA process begun.
    “Twelve of these seed nests were obtained from the western third of Bri-Mar Stable, and 6 were recovered and relocated within the Boat House itself.”
    Once an Environmental Assessment (EA) has been initiated, it is illegal to take actions that limit the range of reasonable alternatives laid out in the EA. The removal of nests from the Stable is illegal (NEPA violation), because one option in the EA is letting the stable stand with no maintenance (no action).

    The Audubon Report was co-authored by two FWS employees.
    Two Report authors are in conflict of interest as FWS officials, one of them the chief proponent for the project being studied.

    Reply

Leave a Reply to Nancy Goodman Cancel reply

Your email address will not be published.