Resource Equivalency Analysis for cat control program as compensatory mitigation for incidental take of songbirds
Another title for this blog post could be Hot Mess: Solar Tower, Bird/Wildlife Deaths and Cats
The process for the controversial Palen solar electric generating project [California Energy Commission Docket Number 09-AFC-07C] and its related feral cat predation aspect are fascinating (on one level!) The project would be sited on 3,794 acres (almost 6 square miles?) of public land managed by the BLM near Desert Center California and Joshua Tree National Park in eastern Riverside County. How many feral cats are even in this desert area, isn't it low human habitancy? What are the impacts to desert wildlife and birds from habitat destruction, impact with towers, solar flux? There is a report out on wildlife damage at Ivanpah in San Bernadino County, another BrightSource Energy solar project, as well as a federal study confirming the hazard of aviation glare from Ivanpah.
Some interesting points about the Palen Solar Tower Project for the Feral Cat Blog! are
* why feral cats came up as an impact. Again, how many are there now or will be drawn there from human activities? (in a fairly brief search I didn't find any original project info about cats.)
* what seems like a diversion by Erickson and Levenstein (reps for applicant solar company) to imply impacts from the solar project as lesser than other causes of avian mortality by repeating the Loss, Marra, Will claim that cats are the number one cause of avian mortality (per Erickson, after climate change and habitat loss.)
* the creation by Erickson (with Rabie) of a Resource Equivalency Analysis (REA) for a cat control program as compensatory mitigation for incidental take of songbirds "that equates bird mortality with a feral cat removal or neutering (spaying) program."
* the responses of California Energy Commission staff and several intervenors to testimony of Erickson and Levenstein, especially American Bird Conservancy who find the mitigation proposal insufficient because they believe "removal is far superior to spaying and the only sure way to control feral cat populations."
[For awareness, Erickson coauthored the 2005 USDA paper, A Summary and Comparison of Bird Mortality from Anthropogenic Causes with an Emphasis on Collisions, before the 2013/2014 culmination of effort by the freeroam cat/TNR opposition network to create estimates and "journal-published", "peer-reviewed" papers on human-caused avian mortality.]
Here are excerpts from some of the July 2014 documents, always read entire!
Ex.1134 - Biological Resources Supplemental Opening Testimony Wally P. Erickson and Dr. Ken Levenstein - Avian Impacts
As identified by many bird conservation groups, feral cats represent a significant threat to bird and other wildlife populations. See Exhibit 1163, letter from American Bird Conservancy, National Audubon Society, and others to the US Secretary or Interior, and Exhibit 1164, letter from the American Bird Conservancy to the US Secretary of Interior. After reviewing the letters, WEST developed a resource equivalency analysis that equates bird mortality to a feral cat removal or neutering (spaying) program (see Attachment A). PSEGS is not proposing to conduct its own feral cat program, but believes the TAC could direct funding to existing or new programs that can have a significant positive effect on passerines and songbirds to adequately mitigate the mortality impacts the PSEGS could have on those groups of birds. The current version of Condition of Certification BIO-16a, developed by the Commission Staff and agreed to by PSH, provides the flexibility of the TAC to direct funding to animal control programs.Attachment A at the end of the above document is:
Determining the number of songbirds taken per cat per year is difficult because predation is difficult to observe. Estimates of cat predation rates on songbirds range from 4 to more than 100 per year (Exhibit 1165), again, with most published estimates assumed to be conservative (i.e., low). We used a value near the middle of the range of reported rates to calculate the number of songbirds expected to be taken by a female cat, her daughters, and her matrilineal granddaughters (see Attachment A). Each generation is calculated independently of the others, so the number of songbird mortalities resulting from one cat plus one generation of her female offspring is 112 + 874 = 986 songbird mortalities per female cat. Alternatively, if a neutering program is used, and songbird credits are calculated over two generations of offspring, 874 songbirds may be saved per female cat spayed.
By including two generations of offspring in the analysis, a spaying program alone could result in 874+20,618 songbirds saved per female cat. Attachment A and the values presented here are in terms of female cats produced per female. If a cat control or spaying and neutering program is implemented for both sexes, as is likely to be the case, total credits would be half of what is calculated here. This is conservative inasmuch as male cat-years in generations two and three are not counted towards the bird credit. Clearly, as suggested by the bird conservation groups in the previously-mentioned letters, contributions to programs designed to reduce bird mortality from feral cats could greatly benefit birds, especially songbirds.
A primer on Resource Equivalency Analysis and its application to a cat control program as compensatory mitigation for incidental take of songbirds
Paul Rabie and Wally Erickson – WEST Inc.
Resource equivalency analysis (REA) is a modeling strategy that allows ‘apples to apples’ comparisons among apparently dissimilar resources. In this document we construct a prototypical equivalency model that relates cats to songbirds through the process of predation.
American Bird Conservancy responds to the PSEGS Biological Resources Supplemental Opening Testimony of Erickson and Levenstein:
Unfortunately, the proposal is insufficient and fails to heed the major point of the referenced ABC letters. The testimony states that “after reviewing the letters, WEST developed a resource equivalency analysis that equates bird mortality to a feral cat removal or neutering (spaying) program.” This analysis and overall recommendation to remove or neuter/spay feral cats fails in several important ways.
•The assumption that removal and neutering/spaying are fundamentally equivalent ecologically or as a control method is inaccurate. Removal is far superior and the only sure way to control feral cat populations.
•The referenced letters, signed by ABC and others, specifically request that feral cats be removed from the environment and never re-abandoned. When not removed, feral cats continue to kill wildlife and to perpetuate public health risks (e.g., rabies, toxoplasmosis).
•The analysis does not cite sources and makes questionable assumptions about feral cat behavior and survival probabilities.
BASIN AND RANGE WATCH REBUTTAL TESTIMONY
On Page 5- “After the effects of climate change and habitat loss, studies to date have indicated the highest mortality of birds due to anthropogenic causes comes from predation by domestic and feral cats (Loss et al. 2013) followed closely behind by collisions with windows (e.g., from houses, office towers, commercial structures; Klem 2009).”
One of the ways BrightSource intends to mitigate or offset flux kills for songbirds is by spaying and neutering feral cats. Feral cat populations are not likely to be large in the Chuckwalla Valley due to predators like coyotes, so this mitigation would have to take place elsewhere. Specifically, this mitigation would not be meaningful in areas outside of the Colorado River section of the Pacific Flyway.
Compensatory mitigation of spaying and neutering feral domestic cats in urbanized settings would not compensate for the deaths of songbirds at the Palen site. The species of birds would be very different. Cats prey mostly on common urban species that are often introduced from Europe such as house sparrows. The Palen site would have native desert species such as loggerhead shrikes, black-throated sparrows, verdins, and blue-gray gnatcatchers. Destruction of desert bird habitat and solar flux mortality in a wild desert valley will not be mitigated by controlling cat populations in urban areas, urban fringes and small communities. These areas are quite different than un-fragmented desert ecosystems. BrightSource has not provided a list of songbird species that would be saved with this mitigation.
Furthermore, it seems to be a value judgment on the part of the applicant to suggest that this mitigation would somehow provide ecological compensation for the damage inflicted by their proposed project. To simply say the solar flux kills and injuries would not be as significant if feral cats are sterilized avoids the actual challenge of finding a mitigation that works – which the applicant has failed to find.
[California Energy Commission] Staff's Rebuttal Testimony
[two excerpts, always read entire]
Other Anthropogenic Sources of Avian Mortality
In an attempt to reduce the significance of mortality caused by PSEGS, the Petitioner provides mortality numbers from wind farms, hunting, feral cats, and a suite of other anthropogenic sources (See Exhibit 1157 TN 202506). The Petitioner states: “It is very important to put these numbers into some context. In fact, the most significant concern over impacts to many wildlife populations, including birds, is over the effects of climate change (Foden et al. 2013) and habitat loss (BirdLife International website).” (TN 202484 Page 4)
Staff is aware of the risk to birds from the anthropogenic sources provided by the Petitioner and global climate change. However, staff believes referencing nationwide mortality estimates and comparing avian loss to low-risk, managed species such as ducks (non-sensitive species that are extensively managed and regulated by resource agencies) or loss from collisions with windows or vehicles obfuscates the risk to birds from PSEGS. Many of the species present in the PSEGS area are sensitive and regulated by state and or federal agencies because their populations have declined or are at risk of extinction. The Petitioner suggested that “Studies like Longcore et al. (2013) and Erickson et al. (2014, in review) suggest that avian mortality cumulatively from thousands of communication towers and wind turbines for the great majority of waterfowl, songbirds, and waterbirds, is a relatively minor source of mortality for individual species populations.” This statement may be true for robust common species but does not account for local populations of sensitive birds where the removal of a small number of birds may affect the persistence or recovery of a local population. It is inappropriate to dilute impacts to species that may be subject to mortality at PSEGS by comparing them to nationwide mortality estimates.
Assertions by the Petitioner that PSEGS has lower risk factors (TN 202484 Page 5-6) because the facility does not appear to be in a high bird use area, does not have guy wires, and the towers are solid rather than composed of lattice steel is overstated. The towers are approximately 750 feet tall and structures such as these represent a documented collision risk. The use of intermittent red lighting on the towers is a requirement and while this would reduce collision risk it would not eliminate collision events. Staff believes the contention that PSEGS has lower avian use is misleading.
The data collected by the Petitioner is extremely useful and represents a solid effort to collect data. However, one year of surveys cannot fully account for the migratory use of the PSEGS region. Migration counts are often highly variable, from hour to hour, day to day, and year to year, in large part due to variability in weather conditions that provide lift for raptor migration or concentrate birds in certain landscape features. More importantly surveys conducted by the Petitioner documented 185 species of birds including 32 species considered sensitive at the state or federal level. Some of these
include the state listed Swainson’s hawk, bank swallow, willow flycatcher, and Gila woodpecker. Two fully protected species including the golden eagle and peregrine falcon were also observed. Six federal priority shorebirds were observed at the ponds adjacent to the PSEGS. At a minimum this demonstrates the area is used by a wide variety of resident and migratory species.
The Petitioner stated: “PSEGS has voluntarily committed compensatory mitigation funds to help offset bird mortality that occurs due to operations at the Project. These funds will be directed to programs that benefit birds of taxa similar to those impacted by the project. For example, if songbirds incur fatalities, contributions will be made to programs that benefit songbirds.” (TN 202482 Page 11)
Staff has provided previous testimony regarding the development of mitigation to reduce impacts to resident and migratory birds and recommends the TAC be used to focus mitigation efforts for target species. Implementing mitigation such as spaying or neutering of feral cats (TN 202482 Page 13) would reduce impacts to some groups of birds but staff cautions many of the bird deaths reported likely occur in urban areas where many sensitive native species have already been displaced. Mitigation efforts may be better focused on habitat creation or bird management activities.
K. Shawn Smallwood Rebuttal Testimony [for Center for Biological Diversity]
. . . In summary, Erickson and Levenstein’s predicted impact of 1,700 birds per year is not believable.
Beginning on page 4 and continuing through page 5, Erickson and Levenstein argued that the Palen impacts will be minimal in light of other anthropogenic causes of wildlife mortality, such as dogs and cats and cars and buildings. The argument made by Erickson and Levenstein appeared intended to downplay the impacts solar energy generation on avian species, but actually helped make the case that Palen’s project impacts will be cumulatively considerable. I agree that the anthropogenic impacts described by Erickson and Levenstein are devastating, but I disagree that they justify the deaths of thousands of birds and unknown numbers of bats at the Palen project.
Erickson and Levenstein identified a series of measures that will be funded to reduce impacts to the types of animals that will be killed by Palen. These measures included marking fences, neutering cats, marking power lines, marking windows, and retrofitting power poles. However, there was little in the way of any nexus described between the conservation benefits of these measures and the project impacts caused by Palen. Will enough cats be neutered to save as many birds as will be killed at Palen? Will they benefit the same species or populations?
On page 14 Erickson and Levenstein proposed numbers of songbirds that could be saved by neutering a single female cat. The numbers were very large, and difficult to believe would translate to real birds in the wild. It was a large leap in logic to assume that the number of young never born to a neutered cat would go unreplaced by kittens born to another cat. In other words, the cat population will compensate for some of its members being neutered, just as cat populations have always done this. I am fully supportive of neutering feral house cats, but I think it is misleading to claim that the numbers of birds not killed by the cat’s prevented offspring will be spared the cats that are not neutered. Some benefit to birds will be realized by neutering, but not at the levels claimed by Erickson and Levenstein.
Some other cat-related documents (I was already familiar with their content):
plus the two letters to USDOI from conservation groups that I shared when they came out! (see below)
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related previous Feral Cat Blog! posts:
search blog with keywords such as avian mortality, bird mortality, bird deaths, cat predation, environmental, Pimentel, and many more!
TWS and SCB letter to DOI to eradicate feral cats
Freeroam cats on public lands ABC to DOI