Federal Register / Vol. 60, No. 58 / Monday, March 27, 1995 / Rules and Regulations 15693

(b) Includes one or more mirrors

which together provide, at the driver’s

eye location, a view of:

(1) For the mirror system on the right

side of the bus, the entire top surface of

cylinder N in Figure 2, and that area of

the ground which extends rearward

from cylinder N to a point not less than

60.93 meters (200 feet) from the mirror

surface.

(2) For the mirror system on the left

side of the bus, the entire top surface of

cylinder M in Figure 2, and that area of

the ground which extends rearward

from cylinder M to a point not less than

60.93 meters (200 feet) from the mirror

surface.

* * * * *

Issued on: March 20, 1995.

Ricardo Martinez,

Administrator.

[FR Doc. 95–7348 Filed 3–24–95; 8:45 am]

BILLING CODE 4910–59–P

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

Endangered and Threatened Wildlife

and Plants; Notice of Determination To

Retain the Threatened Status for the

Coastal California Gnatcatcher Under

the Endangered Species Act

AGENCY: Fish and Wildlife Service,

Interior.

ACTION: Notice of determination.

SUMMARY: The Fish and Wildlife Service

(Service), announces a determination

affirming its earlier conclusion (March

30, 1993; 58 FR 16742) that the coastal

California gnatcatcher (Polioptila

californica californica), a small,

insectivorous songbird, is a distinct

subspecies and, thus, meets the

definition of a ‘‘species’’ pursuant to the

Endangered Species Act of 1973, as

amended (Act). In addition, the Service

affirms its earlier conclusion (58 FR

16742) that the southern limit of this

subspecies extends to about 30° north

latitude near the vicinity of El Rosario,

Baja California, Mexico. Based on these

determinations, the Service concludes

that its March 30, 1993, decision that

the coastal California gnatcatcher is a

threatened species was correct. Federal

protection for the coastal California

gnatcatcher is thus continued.

EFFECTIVE DATE: March 23, 1995.

ADDRESSES: The complete

administrative records and files for this

determination and all related rule

promulgations and notices are available

for inspection, by appointment, during

normal business hours at the Fish and

Wildlife Service Carlsbad Field Office,

2730 Loker Avenue West, Carlsbad,

California 92008.

FOR FURTHER INFORMATION CONTACT: Mr.

Gail C. Kobetich, Field Supervisor, at

the above address (telephone 619/431–

9440).

SUPPLEMENTARY INFORMATION:

Background

The coastal California gnatcatcher

(Polioptila californica californica), a

subspecies of the California gnatcatcher,

is a small, long-tailed member of the

thrush family Muscicapidae. The

subspecies is restricted to California and

Baja California, Mexico, and is an

obligate resident of coastal sage scrub,

which is one of the most depleted

habitat types in the United States (58 FR

16742). The plumage color of the

species is dark blue-gray above and

grayish-white below. The tail is mostly

black above and below. This subspecies

is distinguished from the other

subspecies by its darker body plumage,

less extensive white on tail feathers

(rectrices 5 and 6), and longer tail

(Atwood 1991). The male has a

distinctive black cap that is absent

during the winter. Both sexes have a

distinctive white eye-ring. Vocalizations

of this species include a call consisting

of a rising and falling series of three

kitten-like mew notes (National

Geographic Society 1983).

The California gnatcatcher was

originally described as a distinct species

(Polioptila californica) by Brewster

(1881) based on specimens collected by

Stephens in 1878. Later taxonomic

treatments (e.g., Coues 1903 and

Chapman 1903) reflected Brewster’s

(1881) conclusions. Grinnell (1926),

however, later concluded that the

species was a form of the black-tailed

gnatcatcher (Polioptila melanura),

which inhabits the Sonoran and

Chihuahuan Deserts of the southwestern

United States and northwestern Mexico.

Subsequent scientific publications

(American Ornithologists’ Union 1931,

Grinnell and Miller 1944, Friedmann

1957, American Ornithologists’ Union

1957) adhered to the species limits as

defined by Grinnell (1926). Three

subspecies of the black-tailed

gnatcatcher were recognized for

southwestern California and western

Baja California, Mexico: P. m.

californica (ranging from Los Angeles

County, California (formerly northward

to Ventura County), south to about 30°

north latitude in Baja California,

Mexico), P. m. pontilis (resident in

central Baja California), and P. m.

margaritae (ranging from about 27°

north latitude south to the Cape region

of Baja California) (American

Ornithologists’ Union 1957).

Based on identified differences in

ecology and behavior that were

elucidated as a result of specimen study

and statistical analysis, Atwood (1988)

proposed that Polioptila californica was

specifically distinct from P. melanura.

This finding was subsequently formally

adopted by the American

Ornithologists’ Union Committee on

Classification and Nomenclature

(American Ornithologists’ Union 1989),

thus affirming Brewster’s (1881) original

taxonomic placement with respect to

species. The American Ornithologists’

Union 1989 publication did not address

subspecies other than to refer the reader

to the American Ornithologists’ Union

1957 checklist of North American birds.

The coastal California gnatcatcher,

Polioptila californica (=melanura)

californica, has been recognized as a

distinct race or subspecies since

Grinnell’s (1926) publication (e.g.,

American Ornithologists’ Union 1931,

Grinnell and Miller 1944, Friedmann

1957, American Ornithologists’ Union

1957, Garrett and Dunn 1981, Unitt

1984, Phillips 1991, Atwood 1991). As

indicated above, this subspecies occurs

from Los Angeles County (and,

formerly, Ventura County) south to

about 30° north latitude in Baja

California, Mexico. Although Atwood

(1988) proposed merging P. californica

californica with a more southerly

subspecies of P. californica, he later

(1991) retracted this conclusion.

On March 30, 1993, the Service

published a final rule determining the

coastal California gnatcatcher (Polioptila

californica californica) to be a

threatened species (58 FR 16741). In

making this determination, the Service

relied, in part, on taxonomic studies

conducted by Dr. Jonathan Atwood of

the Manomet Bird Observatory. As is

standard practice in the scientific

community, the Service did not request,

nor was it offered, the data collected

and utilized by Atwood in reaching his

conclusions. Instead, the Service cited

the conclusions presented by Atwood in

a peer reviewed, published scientific

article pertaining to the subspecific

taxonomy of the California gnatcatcher

(Atwood 1991).

The Endangered Species Committee

of the Building Industry Association of

Southern California and other plaintiffs

subsequently filed a suit challenging the

listing on several grounds. In a

Memorandum Opinion and Order filed

in the United States District Court for

the District of Columbia on May 2, 1994,

the Court vacated the listing

determination, holding that the
15694 Federal Register / Vol. 60, No. 58 / Monday, March 27, 1995 / Rules and Regulations

Secretary of Interior (Secretary) should

have made available the underlying data

that formed the basis of the Atwood

(1988) report in light of the controversy

surrounding inconsistent conclusions

reached by Atwood in his 1988 and

1991 studies.

Following the Court’s decision,

Atwood released his data to the Service.

These data were, in turn, made available

to the public for review and comment

on June 2, 1994 (59 FR 28508). By order

of June 16, 1994, the Court reinstated

threatened status for the coastal

California gnatcatcher pending a

determination by the Secretary whether

the listing should be revised or revoked

in light of his review of the subject data

and public comments received during

public comment periods. This notice

constitutes the Service’s determination

in response to the Court’s June 16, 1994,

order.

Summary of Comments and

Recommendations

A proposed rule to list the gnatcatcher

as endangered was published on

September 17, 1991 (56 FR 47053).

Public comments were solicited and two

public hearings were held on the

proposed rule. Notification of the

hearings was published in the Federal

Register on February 7, 1992 (57 FR

4747). A legal notice announcing the

hearings and inviting general public

comment on the proposal was also

published on February 7, 1992 in the

Los Angeles Daily News, Los Angeles

Times, Riverside Press-Enterprise, and

the San Diego Union-Tribune. Public

hearings were conducted in Anaheim,

California, on February 25, 1992, and in

San Diego, California, on February 27,

1992. A notice of extension and

reopening of the comment period for 30

days to obtain additional information on

gnatcatcher taxonomy was published on

September 22, 1992 (57 FR 43688). On

February 11, 1993, the Service

published a notice announcing the

reopening of the public comment period

on the proposed rule for 20 days and the

availability of a report prepared by

Service taxonomists on the taxonomic

validity of P. c. californica (58 FR 8032).

On March 30, 1993, the Service

published a final rule determining the

coastal California gnatcatcher to be a

threatened species (58 FR 16741). That

same day, a proposed special rule

pursuant to section 4(d) of the Act was

published (58 FR 16758). The final

special rule was published on December

10, 1993 (58 FR 65088).

Following the Court’s Order of May 2,

1994, and receipt of Atwood’s data, the

Service announced the availability of

these data and the opening of a public

comment period on June 2, 1994 (58 FR

28508). Atwood’s data were sent to 15

parties upon request. With the approval

of the Court, the public comment period

was extended to December 1, 1994 (59

FR 53628), to allow the public

additional time to receive and then

comment upon the raw data and

methodology utilized by Atwood.

During this 6-month public comment

period, Dr. William Link and Mr. Grey

Pendleton of the National Biological

Service, Department of the Interior

(Department), conducted a new and

independent analysis of Atwood’s data

(Link and Pendleton in litt. 1994). To

assure that the Service utilizes the best

scientific information available in the

implementing the Act, it is policy (59

FR 34270) to seek independent review

of the scientific basis for listing and

recovery actions. Consistent with this

policy, the Service solicited comments

on the National Biological Service

document and all other public

comments received by December 1,

1994, from the general public, including

scientists with an expertise in avian

taxonomy. A new 30-day public

comment period (59 FR 66509) was

opened on December 27, 1994, to allow

the public to review and comment on

these documents. This final comment

period closed on January 26, 1995.

A total of 31 comments pertaining to

either (1) Atwood’s data, methodology,

or results, or (2) the taxonomy of the

gnatcatcher was received during the

final two comment periods. This total

includes 21 comments received prior to

December 1, 1994, and an additional 10

comments received during the final

comment period. Included among the

comments were three new, independent

analyses of Atwood’s data. After a

review and consideration of all such

comments, five relevant issues have

been identified and are discussed

below. The five issues encompass all

substantive comments pertaining

specifically to Atwood’s data, analyses,

and conclusions regarding the taxonomy

and geographic range of the coastal

California gnatcatcher.

Issue 1: Several commenters noted

that Atwood’s apparent discarding of

raw data precludes an appropriate

analysis of his conclusions. One

commenter in particular was disturbed

that ‘‘Atwood no longer has the raw data

used in his original analyses.’’ Another

commenter noted that Atwood admitted

to discarding computer programs used

in the analysis of the data subsequently

analyzed and reported in his 1991

publication. Some stated that

differences existed between the data sets

used in Atwood (1988), Atwood (1991)

and that provided to the Service and the

public (Atwood in litt. 1994a).

Service Response: Atwood (in litt.

1994b) has stated that the measurements

provided to the general public following

the May 2, 1994, Court Order ‘‘represent

the total and unmodified data set that

formed the basis for my 1988 and 1991

publications on gnatcatcher

morphology.’’ Atwood (in litt. 1994b)

also indicated that only one difference

existed between the computer file data

set transmitted to the public and the

data on the original paper forms that he

discarded after entering the data into a

computer file, the sex of a single

specimen from sample area SI29 was

corrected. Atwood (in litt. 1994b)

further indicated that he verified (in

1985) the data on the computer by

comparing it with the hand-written

information on the paper forms. The

Service concludes that there is no

reason to doubt the veracity of Atwood

in this regard.

Because data on paper forms cannot

readily be subjected to statistical

analysis, the data transferred to a

computer or computer disk are, in

essence, the raw data at issue. The

Service, therefore, rejects the contention

that Atwood discarded his raw data,

thereby precluding reanalysis of the

data.

After providing his data, Atwood

realized that discrepancies in sample

size existed between data reported in

his dissertation, his monograph

(Atwood 1988), his subspecies paper

(Atwood 1991), and data provided to the

Service. He noted that for site SI29 there

was a discrepancy with respect to one

female and one male specimen and

concluded that he had corrected the sex

for one individual. His dissertation

revealed 14 specimens for sites PP28

and MA30, whereas the Service data

includes 13 specimens for site PP28 and

15 for site MA30. Atwood believes that

this discrepancy was the result of

correctly placing one specimen in site

MA30 rather than PP28. These two

corrections resulted in apparent

discrepancies. Atwood was unable to

explain an additional discrepancy, in

his dissertation he reported 19 female

specimens for site SD24, whereas the

data provided to the Service indicates

20 female specimens for site SD24;

Atwood suggested that a typographical

error had occurred.

Atwood discovered numerous

discrepancies between the sample sizes

for his monograph (Atwood 1988) and

the data given to the Service (amounting

to 15 more male specimens and 7 fewer

female specimens reported in the

Service data set). Atwood could not

conclusively explain these
Federal Register / Vol. 60, No. 58 / Monday, March 27, 1995 / Rules and Regulations 15695

discrepancies, but suspected that they

were associated with the differing

lengths of data set lines that may have

caused the SAS program to skip lines or

combine lines of data. He suggested that

this problem may also have affected his

analyses of the data presented in the

1988 monograph. He indicated that

because of these potential problems, he

felt that it is inappropriate to rely upon

the 1988 monograph with respect to

subspecific conclusions, although the

conclusions with respect to species

were unaffected, and are valid.

However, programming errors would

not have affected the original data set.

Atwood (in litt. 1994a,b) has

acknowledged that one of the 213

samples in the data set provided to the

public was not used in his 1991 study

or in his previous, unpublished status

review of the gnatcatcher. Atwood (in

litt. 1994b) believes that the excluded

specimen was that designated YP2717,

an aberrant specimen (possibly a blacktailed gnatcatcher or interspecies

hybrid) collected in 1885. In Atwood’s

subsequent reanalysis of the original

data set, specimen YP2717 was

excluded from the data set because it

differed from its sample area mean by

more than 3 standard deviations

(Atwood in litt. 1994b).

The sample size discrepancies for all

reports, except the 1988 monograph, are

very minor, and would not have affected

the overall conclusions of the authors.

Atwood (1994b) has characterized the

analysis of his 1988 monograph as being

‘‘seriously flawed’’ with respect to data

processing. The sample size

discrepancies between Atwood’s other

reports, and the 1988 monograph are

likely due to these data processing

problems, and not the result of changes

made to the data set. The Service,

therefore, concludes that the data set

provided by Atwood to the Service

adequately duplicates the data

originally written on paper forms.

Issue 2: One commenter noted that

two of Atwood’s publications (1988 and

1991) were contradictory in that they

proposed different geographic ranges for

the taxon of California gnatcatchers

occurring in the United States. This

same commenter suggested that

Atwood’s (1991) retraction of his

original (1988) conclusions pertaining to

the subspecies taxonomy of the

California gnatcatcher was prompted by

his desire to affect the listing of the

species.

Service Response: While the record

indicates that Atwood believes that the

listing of the coastal California

gnatcatcher is warranted, the record also

indicates that Dr. Atwood’s revised

conclusion about the subspecific

geographic limits of Polioptila

californica californica resulted from his

1991 reanalysis of the data cited in his

1988 monograph. The (1988)

monograph had received peer review

critical of its findings.

The Service receives dozens of

petitions to list or delist species each

year. The Act requires the Service to

conduct an independent review of each

of these petitions, and to make final

decisions on the basis of the best

scientific data available. The motives of

the petitioners, as with commenters, are

not relevant to the Service’s decisions

on these issues.

Issue 3: Several commenters alleged

fundamental flaws in the data used by

Atwood (1991) in generating his

conclusions. In particular, commenters

suggested or concluded that the data

appeared to be incomplete, or nonrandom (i.e., ‘‘censored’’). Several

commenters were concerned that the

variables were ‘‘confounded’’ (i.e., the

effects of two or more factors on a

response variable could not be

separated) due to the age or condition of

certain specimens. These commenters

indicated that for the northern sites

nearly all specimens were collected

prior to 1940, and none of the

specimens from the remaining sites

were collected prior to 1920. One

commenter noted that a potential exists

for serious bias in the data due to

specimen ‘‘foxing’’ (i.e., browning with

age). Another commenter noted, citing

relevant published scientific literature,

that body size and plumage brilliance

and iridescence can reflect variation in

specimen condition. Some of these

commenters suggested that differences

in characters among sites may be the

result of the age of the collection, and

not the site from which they were

collected.

Service Response: On behalf of the

Service, the National Biological Service

independently conducted a new

analysis of Atwood’s data (Link and

Pendleton in litt. 1994). Three

additional independent analyses of the

data were also submitted during the

comment period.

In response to one commenter’s

concern that the data appeared to be a

non-random sample of California

gnatcatchers, the National Biological

Service (Newton, in litt. 1995) replied

that although these are valid concerns,

they are not proof, as acknowledged by

the commenter, that Atwood’s data are

not representative. One commenting

ornithologist who was largely critical of

Atwood’s (1991) analyses nevertheless

concluded that ‘‘[t]he data set gathered

by Atwood was quite comprehensive

and included measurements from a

large number of specimens throughout

the range of the species.’’ In the

Memorandum Opinion and Order filed

May 2, 1994, the Court declared, citing

the declaration of this ornithologist, that

‘‘it is not disputed that Atwood’s means

of collecting data were proper.’’

After noting the possible problem of

the age of the specimen being

confounded with the collection site, the

authors attempted to adjust the data for

year or month the data was collected.

McDonald et al. (in litt. 1994) removed

specimens collected from May to

September and thus avoided problems

associated with feather wear. Link and

Pendleton (in litt. 1994) adjusted several

characters for month and year based on

the results of regression analyses.

Messer (in litt. 1994) conducted two of

her analyses by limiting the specimens

to those collected between 1920 and

1940, and 1980 to 1984. Link and

Pendleton (in litt. 1994) were cautious

and indicated that they may not have

removed all of the confounding effects;

however, they also indicated that they

may have over adjusted the data and

removed differences due to sites.

After adjusting the data for year and

month of collection, Link and Pendleton

(in litt. 1994) obtained results similar to

the unadjusted data. Messer (in litt.

1994) was able to classify the northern

birds from the southern birds using

specimens collected from 1980 to 1984

correctly in 84 percent of the cases, and

using birds collected from 1920 to 1940

in 94 percent of the cases. The results

of McDonald et al. (in litt. 1994) also

yielded weak evidence of a break at 30°

north latitude, even though they had

removed birds collected during certain

months of the year. Atwood (in litt.

1994b) also had similar results before

and after he excluded the variable

brightness of breast plumage (a variable

that would have changed as a specimen

aged) from his analysis.

Given the above considerations and

results, the Service finds no justification

or cause for concluding that Atwood’s

data were incomplete, censored, or

otherwise inadequate. Further, the

Service concludes that the available

information does not support the

hypothesis that the confounding of

variables is responsible for erroneous

conclusions regarding perceived breaks

in the morphology of the coastal

California gnatcatcher. The Service

concludes that the analysts took

adequate care to remove the possible

effects of confounding of age of

specimen and collection area.

Issue 4: The Service received four

significant analyses and a number of

critiques of each of the analyses of

Atwood’s data. Each commenter
15696 Federal Register / Vol. 60, No. 58 / Monday, March 27, 1995 / Rules and Regulations

attempted to answer a different

question, and consequently, each of the

analyses used somewhat different

statistical techniques, and drew

somewhat different conclusions. Some

of the commenters concluded that the

clinal nature of the data would argue

against subspecies; or that a primary

break occurs further south and would

argue that if there are subspecies, the

boundary line should be drawn further

south in Baja California. Others argued

that the data are clumped (consistent

with a subspecific break); or that the

birds north of 30° north latitude are

different from the birds south of 30°

north latitude. The Service analyzed

these reports to draw a conclusion

regarding whether the data support

Atwood’s 1991 conclusions.

Service Response: Several

commenters produced new analyses of

the data provided by Atwood. Atwood

(in litt. 1994b) also provided an

additional taxonomic analysis of the

data. With the exception of Atwood (in

litt. 1994b), all of the authors (Messer in

litt. 1994, Link and Pendleton in litt.

1994, and McDonald et al. in litt. 1994)

explicitly stated that their expertise is in

statistics, and that taxonomic

conclusions should be left to

taxonomists. The Service has carefully

reviewed each of these analyses and

critiques to examine the strengths and

the weaknesses of each approach. A

summary of these analyses follows.

Atwood (in litt. 1994b) presented a

reanalysis of his data using log10

transformations of 6 variables (bill

length, tarsus length, wing length, tail

length, length of white spot on a tail

feather (retrix 6), and brightness of

breast plumage). In one analysis, he

excluded the variable ‘‘brightness of

breast plumage’’ because Mellink and

Rea (1994) found readings inconsistent,

even when resampling a single

specimen. Atwood used a TukeyKramer method to conduct pairwise

comparisons of the sample area means.

He also conducted a principal

components analysis (a method of

determining how the data are

intercorrelated, and reducing

intercorrelated data to a principal

component score) of the data and

performed a cluster analysis on the first

two principal component scores as well

as on the original variables. Tail length,

tail spot length, and brightness of breast

plumage varied significantly among

sample areas (all P<0.001), and multiple

comparison tests revealed a grouping, or

‘‘step,’’ at 30° north latitude. The cluster

analyses grouped sites north of 30°

north latitude together, and variously

grouped sites to the south. Atwood’s

methods show that regional means may

be clumped, but do not show whether

individual birds can be placed correctly

into these groups.

Link and Pendleton (in litt. 1994)

used regression analysis of mean

latitudes of Atwood’s (1991) nine

sample areas against 25 characters. They

determined that the data vary along a

geographic gradient. Link and Pendleton

(in litt. 1994) then conducted a series of

tests to determine if the characters were

representative of gradual change or of

groupings. They used multivariate

analysis of variance (MANOVA) to place

the original 9 sites into the best

groupings of 8 sites, 7 sites, 6 sites, 5

sites, 4 sites, 3 sites and 2 sites. Abbott

et al. (1985), in their book on taxonomic

analysis, recommended the use of

canonical variate analysis (MANOVAs)

for delineation of subspecies, where the

data are continuous and the data are

preclassified into postulated groups.

Akaike’s information criterion (AIC) was

used by Link and Pendleton (in litt.

1994) to determine which grouping best

fit the data. Link and Pendleton (in litt.

1994) conducted discriminant function

analysis to determine if they could

correctly classify birds into groups.

Hotelling’s t2 test was used to test the

significance of the results. Cluster

analysis and discriminant coordinates

were computed on the individual

specimens to see how the data was

clumped. Finally, they attempted to

adjust the data for time effects (see issue

3 above).

Link and Pendleton (in litt. 1994)

obtained similar results in each of these

tests. They concluded that the changes

in the characters are more representative

of groupings than of gradual change.

They determined that, at least one break

occurs north of site 5 (mean latitude of

site 5 is 29.5° north latitude) and at least

one break occurs south of site 5. The use

of MANOVA would reduce the

likelihood of Type 1 error (reporting

differences that do not exist) that would

occur if you looked at each variable

separately. The AIC is not prone to

overfitting, and can be used to

determine the model that best fits the

data. The AIC does not have an

associated statistical test for

significance, and therefore, the groups

identified in this manner may not

represent actual groupings (Newton in

litt. 1995). Though Newton (in litt. 1995)

also indicated that Atwood’s (in litt.

1994b) cluster analysis would have been

more useful if he had used individual

specimens rather than group means,

Link and Pendleton’s (in litt. 1994)

cluster analysis did use individual

specimens and yielded groups similar to

their MANOVA results, creating a

stronger basis for their conclusions.

Messer (in litt. 1994) examined

whether the birds north of 30° north

latitude can be distinguished from the

birds south of 30° north latitude. She

used multivariate discriminant analysis

to classify birds into northern and

southern subgroups with the boundary

set at 30° north latitude. Discriminant

analysis is used when one is examining

a categorical dependent variable (e.g.,

north or south of 30° north or one of 9

sites) and metric independent variables

(e.g., measurements of gnatcatcher

characteristics). Discriminant analysis

would test whether the means among

groups are equal. Using several subsets

of the data (e.g., limiting years of

collection to remove time effects, or in

developing a model with one set of data

and another to test the model), Messer

(in litt. 1994) concluded that one could

correctly classify the birds as being from

the northern or southern areas with 86

to 92 percent accuracy.

McDonald et al. (in litt. 1994)

conducted their analyses using

individual specimens, and estimated the

latitude based upon the locality

description given by Atwood in his

original data set. They removed

specimens collected from May through

September to avoid data problems due

to feather wear and molting, and

attempted to adjust some data for year

of collection. To examine how the data

are intercorrelated, they conducted

principal components analysis on size,

color, and pattern variables separately.

McDonald et al. (in litt. 1994) conducted

Gabriel’s sum of squares simultaneous

test procedure on the first principal

component scores and on the original

variables. McDonald et al. (in litt. 1994)

conducted an intervention analysis to

look for steps or breaks in the trends in

means. In addition, they conducted a

discriminant function analysis to

determine whether birds could be

correctly classified at various latitudes.

The results from the Gabriel’s test

indicated that there were significant

differences in means of the first

principal component at 24° north

latitude, and that for some of the size

variables there was weak evidence for a

trend in means at 28° north latitude or

27° north latitude. There was weak

evidence for difference in the means at

30.5° north latitude for the first

principal component for color variables.

The intervention analysis revealed a

significant rate of change for 4 of the 16

individual size variables (page 6) at 30°

north latitude (P< 0.10). The

discriminant function analysis revealed

that the lowest misclassification rate

was at 24° north latitude (4 percent).

The misclassification rate at 30° north

latitude was 13 percent (a 25 percent
Federal Register / Vol. 60, No. 58 / Monday, March 27, 1995 / Rules and Regulations 15697

misclassification rate is generally

acceptable for many subspecific groups).

McDonald et al. (in litt. 1994) used

principal components analysis (a

method to reduce intercorrelated data to

a single principal component score) on

size, color, and pattern variables

separately. This analysis may have been

done to group data by measurement

type (e.g., units of length, weight, etc.),

as is recommended in some statistics

books (Newton in litt. 1995). Other

statistics texts (e.g., Hair et al. 1995)

apparently do not recommend grouping

like measurements. A more exhaustive

approach to principal components

analysis would have been to do the

analysis on all variables simultaneously,

then exclude size variables, then pattern

variables, and so forth (Newton pers.

comm. 1995). In that manner, McDonald

et al. may have detected additional

intercorrelations among gnatcatcher

characteristics.

McDonald et al. (in litt. 1994)

presented a stronger case for breaks in

characters south of 30° north latitude

than they did for characters found at 30°

north latitude. Atwood (1991, in litt.

1994), and Link and Pendleton (in litt.

1994) also found breaks south of 30°

north latitude. The evidence of at least

one break south of 30° north is

supportive of Atwood’s (1991)

conclusion of an additional subspecific

break. McDonald et al. (in litt. 1994)

provided the strongest evidence against

Atwood’s (1991) conclusions.

Nonetheless, they found weak statistical

results supporting a break at 30° north

latitude (Gabriel’s SS-STP and

intervention analysis). They also

acknowledged that Gabriel’s test may

not have detected differences in the

critical region, where Atwood

concluded changes occur, because this

test is sensitive to small sample sizes

(i.e., an investigator needs a large

number of individual records before the

test will detect differences). Thus, in

this portion of the analysis of McDonald

et al., the possibility of a Type 2 error

or accepting the null hypothesis when

it should be rejected (i.e., believing that

there is no break in characters when in

fact one does occur) was higher than the

possibility of a Type 1 error or rejecting

the null hypothesis when it should be

accepted (i.e., believing that there is a

break in characters, when in fact no

break exists).

McDonald et al. (in litt. 1994) also

used ‘‘intervention analysis’’, a

procedure normally used when an

experimenter intervenes in some way

(i.e., provides medical treatment) and

wants to evaluate whether changes in

behavior or performance are statistically

significant (Edgington 1987). McDonald

et al. (in litt. 1994) apparently used this

approach to see if changes at various

latitudes resulted in a sharp step.

McDonald et al. (in litt. 1994) provided

limited details of this method, which

they modified and ‘‘tested using data

from the literature.’’ Therefore, the

Service was unable to fully evaluate this

method, which apparently is not

commonly used. Messer (in litt. 1995),

however, indicated that the technique is

a ‘‘nonparametric (and thus less

powerful) version of linear regression

analysis.’’

McDonald et al. (in litt. 1994) did find

weak statistical evidence for a break in

characters at 30° north latitude, and

were able to distinguish the birds north

and south of this line with a 13 percent

error rate. In evaluating their

techniques, the Service notes that

McDonald et al. (in litt. 1994) used

techniques that were less exhaustive, or

that were less well known, or that may

have been more likely to result in a

Type 2 than in a Type 1 error than

techniques used by the other authors.

The techniques of McDonald et al. (in

litt. 1994) appeared more likely to

accept the null hypothesis (e.g., there is

no subspecific break in gnatcatchers at

about 30° north latitude). Given the

selection of statistical techniques by

McDonald et al. (in litt. 1994), and that

Atwood (in litt. 1994), Link and

Pendleton (in litt 1994), and Messer (in

litt. 1994) found evidence for a break at

30° north latitude, the Service

concludes that the weak statistical

evidence of a break at 30° north latitude

presented by McDonald et al. should be

given greater credence.

In summary, the MANOVA conducted

by Link and Pendleton (in litt. 1994) and

cluster analysis conducted by Atwood

(in litt. 1994) are supportive of

groupings of birds rather than a cline.

Use of cluster analysis by Link and

Pendleton (in litt. 1994) on individual

specimens provides stronger evidence

that groups or ‘‘steps’’ exist in

characters. In addition, efforts by

McDonald et al. (in litt. 1994) and

Messer (in litt. 1994) to determine

correct classification rates provide

further evidence that gnatcatcher

variance along a geographic gradient is

more indicative of groupings than of a

gradual cline. The misclassification

rates at 30° north latitude were well

within the range acceptable for

subspecies.

Each author utilized different

statistical methods to analyze the data

and draw conclusions. As a first step,

the authors investigated whether they

could separate the means among various

groupings of the data. Atwood (in litt.

1994b) used a Tukey-Kramer multiple

comparison procedure to determine if

the means of individual variables among

previously selected groups could be

separated. Link and Pendleton (in litt.

1994) used Hotelling’s t2 on the

groupings identified in their MANOVA

analysis to determine if the means could

be separated. McDonald et al. (in litt.

1994) used Gabriel’s method to

determine differences in means at

selected latitudes. Each of these

approaches was successful in separating

means among groups of gnatcatchers.

The investigators next examined

whether there might be steps in these

changes, or whether one could correctly

classify (or place) the birds within these

groups. Messer (in litt. 1994) conducted

a multivariate discriminant analysis and

found that the birds could be classified

into a groups north and south of 30°

north latitude with an error rate of about

10 percent. Link and Pendleton (in litt.

1994) conducted a clustering analysis to

group individual specimens into

clusters and examined the overlap

between the clusters and the groupings

identified in the MANOVA. McDonald

et al. (in litt. 1994) conducted a

discriminant function analysis to

identify latitudes that separate the range

of the bird into 2 groups with minimal

misclassification rates. Each of these

approaches showed a break in the

characters at 30° north latitude, and was

supportive of Atwood’s (1991)

conclusions.

In a statistically pure sense, these

methods are exploratory in nature and

were useful in identifying hypotheses

that could be tested with respect to the

gnatcatcher. To formally test these

hypotheses, an investigator would need

to make similar measurements on newly

gathered gnatcatcher specimens. Issue 5

below discusses the Service’s response

to this point. However, it is important

to understand that statistics are a tool

used to assist an investigator in drawing

conclusions in that they can help

quantify uncertainties with respect to

those conclusions (Newton pers. comm.

1995). The investigator still needs to

evaluate the practical significance of

results, and should not focus

exclusively on statistical significance

(Abbott et al. 1985, Hair et al. 1995,

Mayr et al. 1953). Statistics do not

remove or supplant the need to make

informed decisions with respect to any

data set. Messer (in litt 1994), Link and

Pendleton (in litt. 1994), and McDonald

et al. (in litt. 1994) all explicitly

recognized that taxonomic decisions

should be made by taxonomists.

The misclassification rates identified

by Messer (in litt. 1994) and McDonald

et al. (in litt. 1994), and the overlap in

many of the characters show that these
15698 Federal Register / Vol. 60, No. 58 / Monday, March 27, 1995 / Rules and Regulations

groupings of gnatcatchers are not

entirely discrete. Abbott et al. (1985)

noted that taxonomists expect

‘‘variation within species to involve

either a continuum or at least some

continuity or overlapping between

forms.’’ If the groupings of California

gnatcatcher were entirely discrete, avian

taxonomists likely would have assigned

these groupings to separate species.

Mayr (1970) defined subspecies as ‘‘an

aggregate of phenotypically similar

populations of a species inhabiting a

geographic subdivision of the range of a

species and differing taxonomically

from other populations of the species.’’

Mayr (1970) concluded that the

magnitude of taxonomic difference

necessary to appropriately decide when

subspecies should be delimited ‘‘can be

determined only by agreement among

working taxonomists.’’

Grinnell (1926), Phillips (1991), and

Atwood (1991) identified 30° north

latitude as a boundary between

Polioptila californica (=melanura)

subspecies. Recent work suggests that

the southern boundary of P. c.

californica may be further north, near

the international boundary between the

United States and Mexico (Mellink and

Rea 1994). Mellink and Rea (1994)

placed the birds between the

international border and 30° north

latitude in a new subspecies. Atwood

identified another subspecific break

south of 30° north. McDonald et al. (in

litt. 1994) and Link and Pendleton (in

litt. 1994) also noted a break south of

30° north latitude, consistent with

Atwood’s (1991) conclusion of an

additional subspecific break. The

consensus among working taxonomists

supports recognition of P. c. californica,

albeit its range may be more restricted

than that proposed by Atwood (1991).

Therefore, the Service concludes that a

finding that 30° north latitude as the

southern specific boundary of P. c.

californica is supported by the available

scientific evidence. Until additional

taxonomic work is published and

accepted by the ornithological

community, the Service will recognize

30° north latitude as the southern

subspecific boundary of P. c.

californica.

Issue 5: Several commenters stated

that analyses of a newly collected

independent data sets should be done to

clarify gnatcatcher taxonomy or resolve

differences of opinion among the

various commenters. One commenter

urged the Service to ‘‘dismiss the

subspecies issue for gnatcatchers

(pending further study) and focus on the

management of U.S. populations.’’

Another commenter concluded that ‘‘a

rigorous analysis of both morphometric,

reflectance, genetic, and other chemical

data are required to address the problem

in the clearest possible manner.’’ Other

commenters added that the gnatcatcher

should not be listed until the perceived

taxonomic controversy is resolved.

Service Response: The Service fully

endorses and encourages efforts to

assess and refine the taxonomic status of

all species, including the coastal

California gnatcatcher, provided that

any collection of specimens associated

with such efforts does not result in

unacceptable mortality or other impacts.

However, in making listing

determinations, section 4(b) of the Act

requires the Service to make its listing

decisions within set timeframes and

requires the Service to base its listing

decisions on the best scientific and

commercial data available at the time of

the decision. The Service is not

authorized to delay listing decisions

until all studies of arguable utility are

completed, until scientific debate is

exhausted, or until complete consensus

occurs. The Service cannot await the

‘‘next study,’’ which may or may not

occur and which may or may not be

affirmed by the scientific community

through the appropriate peer review

process.

Efforts to conduct further analysis on

the taxonomy and subspecific limits of

the California gnatcatcher would be

costly and time consuming. One could

seek additional museum records not

analyzed by Atwood, or could collect

new specimens. Collecting new

specimens could result in unacceptably

high mortality. Moreover, collecting

new field specimens prior to making a

final decision on this issue is not

practical. Alternatively, investigators

could capture birds in mist nets and

obtain these measurements from live

individuals, which would then be

released. However, additional

researchers would be unable to verify

the results by visiting a museum and

repeating the measurements. As stated

above under issue 4, the Service was

charged with evaluating whether

Atwood’s data supported his

conclusions, and not with carrying out

additional studies to remove any and all

controversy surrounding the taxonomy

of the Polioptila californica subspecies.

Conclusion

The Service has been charged with

scrutinizing data and conclusions

rendered by Atwood, and determining if

his data support his conclusions. The

Act provides that the Service must

render its determination on the basis of

the best scientific and commercial data

available. The Service has made a

concerted effort to obtain and accurately

assess the best scientific and best

commercial information available

regarding the taxonomy and range of the

coastal California gnatcatcher. As an

integral part of this process, the

Service’s statutory mandates and

standard scientific protocol require that

we recognize and act in accordance with

the concepts, conventions, and practices

of the scientific method. To this end, the

Service must seek and seriously

consider (1) data and analysis published

in peer reviewed, scientific journals, (2)

the opinions of recognized experts in

given scientific disciplines, and (3) the

input of the interested public.

In this effort the Service has reviewed

the analyses of the data used by Atwood

in his 1988 and 1991 papers. The

Service finds that the conclusions

reached by Atwood (1991) are

reasonable, and are generally supported

by the additional analyses received.

Under any circumstances that pertain

to the taxonomy of North American bird

species, the Service actively seeks the

publications, input and expert opinion

of the American Ornithologists’ Union

(AOU) and its constituent Committee on

Classification and Nomenclature

(Committee). The Committee and its

publication (Check-list of North

American Birds) are recognized by the

Service, scientists, and scientific

organizations throughout the world as

authorities on avian taxonomy in North

America. Although the AOU has

formally published its positions on the

taxonomy of the California gnatcatcher

and coastal California gnatcatcher

(American Ornithologists’ Union 1957,

American Ornithologists’ Union 1989),

the Service, nonetheless, made a

concerted effort to solicit and receive

the recent, unequivocal, expert opinion

of the Committee and its members.

During a past, prescribed public

comment period, the Service received

responses from four members of the

Committee (including the Committee

chair). The Committee members were

unanimous in acknowledging that

Polioptila californica californica is

currently accepted as a distinct

subspecies and that its southern

distributional limit occurs at 30° north

latitude.

In addition to independently seeking

and reviewing the best scientific

information available from expert

sources pertaining to the taxonomic

status of coastal California gnatcatcher,

the Service also repeatedly solicited

comments or suggestions from the

public, other concerned governmental

agencies, the scientific community,

industry, and any other party interested

in gnatcatcher taxonomy and all other

aspects of the listing decision. In
Federal Register / Vol. 60, No. 58 / Monday, March 27, 1995 / Rules and Regulations 15699

response to these requests for

comments, the Service received a wide

variety of public comments and

opinions, which are discussed earlier in

this notice.

The Service has carefully considered

all public comments received, separate

and independent analyses of Atwood’s

data, the National Biological Service’s

(Link and Pendleton in litt. 1994)

analysis of the data, subsequent review

of all technical submittals from the

National Biological Service (Newton in

litt. 1995) and other interested parties,

the existing scientific literature, and the

information presented in the final

listing rule designating the gnatcatcher

as threatened (58 FR 16742). As a result,

the Service concludes that the taxonomy

and geographic limits of the coastal

California gnatcatcher are as provided

by Grinnell (1926, 1928) van Rossem

(1931), American Ornithologists’ Union

(1931), Grinnell and Miller (1944),

Friedmann (1957), American

Ornithologists’ Union (1957), Paynter

(1964), Garrett and Dunn (1981),

Atwood (1991), and Phillips (1991). All

of these scientific, peer reviewed,

publications present conclusions or

affirmations that the gnatcatcher

(Polioptila californica californica) is

restricted to coastal southern California

and northwestern Baja California,

Mexico, from Los Angeles County (and

formerly Ventura County) south to the

vicinity of El Rosario at about 30° north

latitude.

The Service determines that the

coastal California gnatcatcher is a

distinct taxon and that its geographic

range is that described and considered

in the final listing rule for the coastal

California gnatcatcher (58 FR 16742).

Therefore, the coastal California

gnatcatcher shall remain classified as a

threatened species for reasons that are

stated in the final rule to list the species

(58 FR 16742).

References Cited

A complete list of all references cited

herein is available upon request from

the U.S. Fish and Wildlife Service,

Carlsbad Field Office (see ADDRESSES

above).

List of Subjects in 50 CFR Part 17

Endangered and threatened species,

Exports, Imports, Reporting and

recordkeeping requirements, and

Transportation.

Authority: The authority for this action is

the Endangered Species Act of 1973, as

amended (16 U.S.C. 1531 et seq.).

Authors

The primary authors of this notice are

Loren R. Hays of the Carlsbad Field

Office (see ADDRESSES section), and

Karla J. Kramer of the U.S. Fish and

Wildlife Service, Portland Regional

Office, 911 Northeast 11th Ave.,

Portland, Oregon 97232–4181

(telephone 503/231–6131).

Dated: March 22, 1995.

Mollie H. Beattie,

Director, U.S. Fish and Wildlife Service.

[FR Doc. 95–7549 Filed 3–23–95; 10:39 am]

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