j. RaptorRes. 31(2):175-186 ¸ 1997 The Raptor ResearchFoundation, Inc.

THE LONG-EARED OWL (ASIO OTUS) AND FOREST MANAGEMENT: A REVIEW OF THE LITERATURE

DENVER W. HOLT Owl ResearchInstitute, P.O. Box 8335, Missoula, MT 59807 U.S.A.

ABSTRACT.--InNorth America, 13 of 20 breeding seasonstudies reporting on Long-earedOwl (Asio otus)reproduction were conductedin open country habitats,four in woodland or edge habitatsand three in predominantlywoodland habitat. Sixteenof 22 nonbreedingseason studies that reported com- munal roost siteswere located in forest/edge habitats,five reported locationsin open spaceand one wasfound within forest habitat.There is currentlylittle data to indicate either a negativeor positive effect of forest-managementpractices on this species.Although there appearsto be someevidence of population declinesin specificgeographic areas, these impactshave been attributed to lossof riparian vegetation,conversion of foraging areasto agriculturalfields and reforestationof open habitats.The Long-earedOwl's ecomorphologyis suggestiveof a speciesthat inhabits open country.Additionally, its primary food is small mammals (e.g., microtine and heteromyid rodents) which inhabit open country. Shouldthe Long-earedOwl be considereda forestowl? Research data would suggestno; however,studies from extensive deciduous and coniferous woodlands are needed.

KEYWORDS: Long-earedOwl; forestry; habitat;, diet;, ecomorphology; Asio otus.

El bfiho (Asiootus) y administracitn forestal:un revisode la literatura RESUMEN.-•Ennorte amtrica, 13 de 20 estudiosde tiempos de cria reportadasen el bfiho Asio otus fueron evaluadosen hfbitat del campo amplio, cuatro en bosqueso orillas de hfbitat, y tres en mayoria de hfbitat de bosque.Diecistis de 22 estudiosen tiempossin crla que reportaronsitios de percha comunalfueron 1ocalizadasen bosque/hfbitat de orilla, cinco lugaresreportados en espacioabierto, y uno fue encontradodentro de un hfbitat de bosque.Actualmente poca informacitn indica si los afectos de la administraci6nde bosquesson negativoo positivoen el especie.Aunque parece que un poco de pruebascon reduccitn de poblacionesen fireasespecificas geogrfficamente, estos impactos estrin atri- buido a la falta de vegetaci6ncerca de los rios, conversi6nde fireasde forraje a parcela agricolas,y repoblacitn forestalde hfbitat abiertos.La eco-morfologiadel buho evocauna especieque ocupa el campo abierto. Tambitn, su cornidaprincipipal es mamiferospequefios (i.e. microfine y roedor het- eronmyid) que ocupan camposabiertos. •Debe ser el bfiho consideradoun bfiho del bosque?Infor- maci6n investigadasugieren que no, sin embargo,estudios de bosqueconifero y de hoja caducaextensa es necesaria. [Traducci6n de Rafil De La Garza, Jr.]

The Long-eared Owl (Asio otus)is a widely dis- Long-eared Owl has been considered an open tributed Holarctic species,with six recognizedsub- country species, inhabiting areas such as grass- species (Cramp 1985). In the Northern Hemi- lands, shrubsteppe,marshes and woodland patches sphere, it ranges from approximately30-65 ø lati- near open areas.Most studiesseem to support this. tude, with isolated populationsoccurring in North To my knowledge,there have been no attemptsto and East Africa, the Azores and Canary Islands evaluatethe affectsof forestrypractices on this spe- (Mikkola 1983, Marks et al. 1994). Someaspects of cies. Herein, I review the literature and use some Long-eared Owl natural history have been well inferencesfrom my ongoing 10 yrs of studyto ad- studied in the U.S. and some European countries, dress some of the questions concerning the im- but most studies have been short in duration, av- pacts of forest management on Long-eared Owls. eraging about two seasons. POPULATION TRENDS In North America, two subspeciesare currently recognized (A. o. wilsonianusand A. o. tuftsi;see Few data exist for population trends of Long- Marks et al. 1994 for further discussion). The cared Owls in North America over the past 10, 25,

175 176 HOLT VOL. 31, No. 2

Table 1. Statusof the Long-eared Owl in North America.

PROVINCE/REGION OR STATE STATUS POPULATION TREND a

CANADA (Fyfe 1976) British Columbia Low Unknown Maritime Low/Medium Fluctuating NorthwestTerritory/Yukon Unknown Unknown Ontario/Quebec Low/Medium Fluctuating Prairie Low/Medium Fluctuating NORTHEASTERN UNITED STATES (Melvin et al. 1989) Connecticut Special Concern Delaware Unknown Massachusetts Special Concern Maryland Decreased Maine Unknown New Hampshire Special Concern New Jersey Unknown New York Unknown Pennsylvania Decreased Rhode Island Special Concern Vermont Special Concern MIDWEST (Petersen 1991) Illinois Endangered Unknown Indiana Uncommon Declining Iowa Threatened Unknown Kansas Uncommon Stable Michigan Special Concern Unknown Minnesota Regular Unknown Missouri Special Concern Unknown Nebraska Unknown Unknown North Dakota SpecialConcern Unknown Ohio Unknown Unknown South Dakota Rare Declining Wisconsin Special Concern Unknown WEST (Marti and Marks 1989) California SpecialConcern Declining Colorado Common Stable Idaho Common Unknown Montana Special Concern Unknown Nevada Common Stable Oregon Common Stable Utah Common Unknown Washington Unknown Unknown Wyoming Common Unknown Trend data not known tbr northeastern U.S.

50 or 100 yrs, but there are some regional data. ada; or 50 detections in the U.S. and Canada The Breeding Bird Survey (BBS) does not include (Droege pers. comm.). the Long-eared Owl in its data set from 1966-89. In Canada, Fyfe (1976) reported population For inclusion, a speciesmust have been detected trends and relative abundanceof raptorsfor prov- on >10 BBS routes in a physiographicregion; 25 incesor specificgeographic areas (Table 1). There or more detections in the three biomes (Eastern, were no data to support these designations.Also Central, Western); 35 or more detections in Can- in Canada, Christmas Bird Count (CBC) results Ju•E 1997 LO•O-EAR•DOW• CO•$ERV^q:•O• 177

50

45

40

35

30

25

20

15,

10.

5 62 64 66 68 70 72 74 76 78 80 82 84 86 88

YEARS

Figure 1. Summary of winter counts of Long-eared Owls from Christmas Bird Counts in the northeastern U.S., 1963-87 (after Melvin et al. 1989). showed a significant decline in Long-eared Owl ern states, Melvin et al. (1989) concluded that no numbers,but thesedata shouldbe interpreted cau- clear population trend could be detectedfor Long- tiously (Kirk et al. 1994). eared Owls, although numbers seemedto fluctuate In the northeastern U.S., Melvin et al. (1989) about every three to six yr (Fig. 1). In New Jersey, reported that the Long-earedOwl was listed as a Bosakowskiet al. (1989, 1989a) analyzed 31 yr speciesof special concern in all the New England (1956-86) of Long-eared Owl Christmas Count states except Maine and decreasingin Maryland Data reporting one or more Long-eared Owls and and Pennsylvania(Table 1). Within the northeast- concludedthat the specieswas declining (Fig. 2).

30-

10- -- = Owls/I,000 party hrs

0 ø Total Owls 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 8'8

Year

Figure 2. Long-earedOwls reported on New JerseyChristmas Bird Counts (dotted line) and per 1000 party hours (solid line). Regressionline (dashed), Y = -0.70x + 25.5, P < 0.0001, r -- 0.67 for party hours is significant. Regressionline, Y = -0.629x + 31.9, P = 0.005, for total owls had a lower correlation (r = 0.50) (after Bosakowski et al. 1989a). 178 HOLT VOL. 31, NO. 2

In the midwestern U.S., Petersen (1991) report- pairs intensively monitored for 9 consecutiveyr, ed that Long-eared Owls have declined in Indiana only 11 males and two females have returned to and South Dakota, are stable in Kansas and are of the same breeding site more than once. Addition- unknown status elsewhere (Table 1). This was ally, no mate fidelity has been recorded. These based on state and regional birding publications data buttressthe argument for highly migratory and raptor surveyforms. In Minnesota, however, and nomadic tendencies in Long-eared Owls. Evans (in Marks et al. 1994) noted a decline in mi- grant Long-earedOwls in his studyarea from 1976- PRIMARY FACTORS RESPONSIBLE FOR LONG-EARED OWL POPULATION TRENDS 93 (Fig. 3). In the western U.S., White (1994) reported the In most cases, there were insufficient data to Long-eared Owl as stable, but with some local convincingly conclude which /hctors influence lossesin the far west. He did not report how these population trends. Population declines have been speciesdesignations were assigned.Marfi and Marks attributed to habitat alteration, forest succession, (1989) reported a Long-earedOwl population de- urbanization, competition with Great Horned Owls cline in California and a stable or unknown popu- (Bubovirginianus), loss of habitat for prey species, lation status in the rest of the west (Table 1). In rodenticides (Bosakowskiet al. 1989a), shooting coastal southern California, Bloom (1994) has and habitat loss (Marks et al. 1994) and loss of shown the Long-eared Owl to have been extirpated riparian habitats and grasslands(Bloom 1994). in some areas,with small remnant populations still Some forestry practicesare also thought to have occurring inland. The number of historic nesting affected Long-eared Owls. In New Jersey, Bosa- areas have declined by 55% (Bloom 1994). In kowskiet al. (1989a) suggestedthat forest removal Montana, Long-eared Owls were listed as a species and thinning affected wintering Long-eared Owls of specialconcern (Marti and Marks 1989). I have and caused them to abandon the area. shown yearly fluctuationsin numbers during CBC On the contrary, many of the nonbreeding and counts and breeding seasons(Figs. 4 and 5) with breeding seasonstudies from the easternU.S. were a consistent research effort in the same areas. In located at roost sitesin plantations of exotic coni- Mexico, the statusof the Long-eared Owl has not fers or other man-made habitats such as cemeteries been reported (Enriquez-Rochaet al. 1993). (Tables 1 and 2). In the western U.S., shelter-belts In summary, realistic population trends for planted for wind and snowbreaks, aswell as cover North American Long-eared Owls are difficult to and food for wildlife have allowed Long-eared determine. The use of CBC data to determine avi- Owls new winter and breeding sites.In other in- an population trends has been controversial,but stances,Long-eared Owls have been radiotracked Root (1988) has presented some of the strengths (Ulmschneider 1990) and found to be using forest and weaknessesto this approach. clear-cutsas foraging areas. Population demographics for Long-eared Owls AFFECTS OF PAST AND PRESENT FOREST MANAGEMENT are uncertain because of the paucity of data on PRACTICES ON LONG-EARED OWLS mortality, emigration, immigration, migration and other factors. BecauseLong-eared Owls are highly There is insufficient information to conclude migratory in some areas,nocturnal, difficult to lo- that forest management has affected Long-eared cate and appear to showfood-based nomadism, it Owl populations.There is some data from NewJer- is very difficult to determine their status. For ex- sey,Minnesota and California that show declines. ample, five notable recoveriesof banded owls in In New Jersey and California, habitat loss or Mexico >800 km f•om banding sitesillustrate the change appearsto have affected Long-earedOwls. Long-eared Owls' high degree of mobility. These Bosakowskiet al. (1989a) theorized that Long- long distancerecoveries include: one owl banded eared Owls in New Jersey were probably rare in Saskatchewan, Canada and recovered 4000 km breeders prior to European settlement. After the awayin Oaxaca, Mexico; one owl banded in Mon- clearing of fbrestsin the 18th and 19th centuries, tana and recovered 3200 km away in Guanajuato, Long-eared Owl populations increased and ex- Mexico; and one owl banded in Minnesota and re- panded in range. When forestswere reestablished covered 3100 km away in Puebla, Mexico. Long- in the 20th century, Long-eared Owl numbers de- term breeding seasonstudies in Montana show lit- clined (Bosakowskiet al. 1989b). In Minnesota, no fie site fidelity by Long-earedOwls. Of 77 breeding explanationfor the apparentdecline has been given. JUNE1997 LONG-EAREDOWL CONSERVATION 179

30-

• 25-

1980 o 1981 •- 20- 1978 • 1982 1986ø CL • 1984 (.- I•) • 10- 1979 o 1977 o o ----•--...•991

0 5- ø ø 1992

0 2O

Years Figure3. Long-caredOwls caught per 1000 net hours in thefall •tt Duluth, Minnesota (D. L. Evans,in Marks et al. 1994). Regressionline indicatesa downwardtrend (Y = 16.25 - 0.59x).

Many studies,however, indicate that exotic and do- that two pairs of radio-taggedLong-cared Owls in mestic conifer plantations,wind-rows and shelter- Idaho avoided scattered areasof juniper (Juniperus beltsplanted near or within open areasprovide ad- spp.) trees within open sagebrush shrubsteppe ditional nestingand winter roostinghabitats that are habitats. The owls generally foraged 1-3 km from beneficial to Long-caredOwls. their nests,with males using about 240-325 ha and femalesusing about 235-425 ha during nightly for- How WOULD LONG-EAREDOWLS BE AFFECTEDBY SIZE, ays. Also in southwestern Idaho, Hilliard et al. SHAPE,AND RESIDUALSOF FORESTCUTS? (1982) reported that one radio-taggedLong-cared This is unknown, but a few studies have data Owl (sex unknown) foraged over 70 ha during which may be relevant.Craig et al. (1988) reported three consecutivenights in winter, and a second

50'

> 30. .--

._

• 20 E

z

ß . :.

86 87 88 89 90

Year

Figure 4. Long-caredOwls recordedon ChristmasBird Countsin westernMontana, 1986-95 (D. Holt unpubl. data). 180 HOLT VOL. 31, No. 2

18

12.

87 88 89 90 91 92 93 94 9•

Year

Figure 5. Breedingpairs of Long-earedOwls observed in westernMontana, 1987-95 (D. Holt unpubl. data). There were no nests found in 1995.

Long-eared Owl (male) foraged over 190-220 ha gy), I found only two studiespertaining to Long- each night for five nights in spring. Ulmschneider eared Owls (Poole 1938, Mueller 1986), but then (1990) reported that seven of 13 radio-tagged incorporated that into literature directly related to Long-earedOwls traveled 73-97 km, and one owl ecomorphologyof birds in general and owlsin par- moved 125 km from a shrubsteppe sagebrush ticular. breeding area to forested mountains. All the owls Habitat Associations.Of 20 studies providing were at first in open country and heavily logged breeding habitat information, only three (Craig- areas, four later moved into forest habitat with head and Craighead 1956, Bull et al. 1989, Bloom small openingswhere three stayedwithin 1 km of 1994) reported that the Long-eared Owl was asso- an active logging site and the fourth stayednear a ciated with forest habitat and only Bull et al. 1-yr-old clear-cut. The three owls near the active (1989) defined the breeding habitat as extensive logging site stayed for several weeks. She felt the forest. Four other studies (Wilson 1938, Armstrong owls had chosen the active logging sites and re- 1958, Reynolds1970, Enriquez-Rochaet al. 1993) cently logged sitesover older ones. described Long-eared Owls as associatedwith for- In Montana, Long-eared Owls nesting in steep est or edge, while the remaining 13 studiesreport- mountain hillsides of second growth Douglas-fir ed Long-eared Owls to be associatedwith open (Pseudotsugamenziesii) forests and mixed pondero- habitats (Table 2). Seventeen breeding season sa pine (Pinus ponderosa)forests adjacent to open studies were conducted in the western Great lands foraged at dusk in nearby clear-cuts and Plains, Great Basin,Rocky Mountains, West Coast grasslands,respectively (Holt and Hillis 1987). and Mexico; six of these were from Idaho. In gen- These observationssuggest that certain logging eral, these studies suggest that Long-eared Owls practicesmay benefit Long-eared Owls. primarily breed in open spaces(but see Peck and Is THE LONG-EARED OWL A FOREST SPECIES? James 1983, in Johnsgard 1988). Other good an- I reviewed studies from across North America ecdotal information refers to Long-eared Owls and tried to address information on habitat asso- heard calling from extensive forest stands (Hay- ciations, diets and ecomorphologyof Long-eared ward and Garton 1988). Owls. I separateddiet into breeding and nonbreed- Of 22 studies providing nonbreeding seasonin- ing seasons.Habitat was separated into grassland, formation, 15 reported that edge habitatswere oc- edge and forest. For ecomorphology(the relation- cupied and five reported open habitats occupied ship between an animal's ecology and morpholo- (Birkenholz 1958, Bosakowski 1984, Marti et al. JUNE1997 LONG-FAREDOWL CONSERVATION 181

Table 2. Breeding and non-breeding seasonhabitat associationsfor Long-eared Owls in North America.

HABITAT LOCATION SOURCE

BREEDING SEASON Forest Michigan Wilson (1938) Michigan Craighead and Craighead (1956) Michigan Armstrong (1958) Oregon Reynolds(1970) Oregon Bull et at. (1989) Mexico Enriquez-Rocha et at. (1993) California Bloom (1994) Edge Michigan Wilson (1938) Michigan Armstrong (1958) Oregon Reynolds(1970) Mexico Enriquez-Rocha et at. (1993) Open Nevada Johnson (1954) Arizona Stophlet (1959) Colorado Marti (1969) Washington Knight and Erickson(1977) Idaho Craig and Trost (1979) Idaho Marks and Yensen (1980) South Dakota Paulson and Sieõ (1984) Idaho Thurow and White (1984) Idaho Marks (1986) Idaho Craig et at. (1988) Idaho Utmschneider (1990) Manitoba, Canada Sullivan (1992) Montana Holt (unpubt. data) NON-BREEDING SEASON Forest Michigan Armstrong (1958) Mexico Enriquez-Rocha et al. (1993) Edge Illinois Cahn and Kemp (1930) Wisconsin Errington (1932) Michigan Spiker (1933) Ohio Randie and Austing (1952) Kansas Rainey and Robinson (1954) Michigan Craighead and Craighead (1956) Michigan Stapp (1956) Michigan Getz (1961) Iowa Wetter and Fredrickson (1963) New York Lindberg (1978) Iowa Voight and Gtenn-Lewin(1978) Pennsylvania Smith (1981 ) Massachusetts Andrews (1982) Massachusetts Holt and Childs (1991) Connecticut Smith and Devine (1993) Mexico Enriquez-Rocha et at. (1993) Open Illinois Birkenhotz (1958) New Jersey Bosakowski(1984) New Mexico Marti et at. (1986) Washington Denny (1991) Montana Holt (unpubt. data) 182 HOLT VOL. 31, No. 2

Figure 6. Geographicdistribution of breeding (©) and non-breeding ( • ) seasonstudies in North America.

1986, Denny 1991). One each reported forest Long-eared Owls. He included data from North (Armstrong 1958) or forest and edge (Enriquez- America, several European countries and Iraq. He Rocha et al. 1993) (Table 2). In contrast to the concluded that I.ong-eared Owls feed on small ro- western breeding studies,18 nonbreeding studies dents found in open country with Microtusvoles were conducted in the midwest and northeast, ex- eaten most frequently, followed by Peromyscusmice cept for four: one in New Mexico (Marti et al. and Heteromyid rodents. 1986), Washington (Denny 1991), Montana (D. Ecomorphology.I reviewed the literature to de- Holt unpubl. data) and Mexico (Enriquez-Rocha termine if the Long-eared Owl's morphology was et al. 1993). The geographic distribution of these consistent with adaptive radiation for particular studies (Fig. 6) is almost nonoverlapping. habitats.Bird groups in general have similar flight Diet. Of 21 nonbreeding season studies repre- morphology, as do birds living in similar habitats. senting45 671 prey, 17 studiesreported a Microtus For example, open country bird species like the vole to dominate the long-ear diet. These volesare Long-eared Owl and Snowy Owl (Nycteascandiaca) open country inhabitants (Table 3). The remain- have more pointed wings for better agility than for- ing prey speciesalso inhabit open country. Results ests owls. Forest owls such as the Great Gray Owl were similar for the breeding seasonbut with slight (Strix nebulosa)and Boreal Owl (Aegoliusfunereus) differencesin prey composition.Of 14 studiesrep- which live in dense vegetation, have short broad resenting 13 858 prey, all except Bull et al. (1989) wings and a large wing area which aid in maneu- reported an open country prey species(Table 4). verability (see Rayner 1988). Bull et al. (1989) reported that Long-eared Owls Owls generally exhibit low wing loading and low nestedin extensivestands of GrandFir (Abiesgran- aspect ratio and are among birds with the lowest d/s) and that the prey speciescomprising the ma- wing loading (Norberg 1987). Relativewing load- jority of the diet was the northern pocket gopher ing is defined as the owls' body mass divided by (Thomomystalpoides). This species is primarily an the wing area or; Mg/S (massM multiplied by the open country inhabitant, but also occurs within acceleration of gravity g, divided by wing area S), openings in closed canopy forests and may move and aspect ratio is defined as wingspan divided by into recent clear-cuts(Ingles 1967). mean chord length, or lfl/S (wingspanb squared, These data are further supported by Marti's divided by wing area S, or wingspan divided by (1976) extensivereview of the feeding ecologyof mean wing chord) (Norberg and Norberg 1986). JUNE1997 LONC,-EAREDOWL CONSERVATION 183

Table 3. Non-breeding seasondiet of Long-eared Owls in North America.

HABITAT DOMINANT GROUP N LOCATION SOURCE

Edge Peromyscus 1198 Illinois Cahn and Kemp (1930) Microtus 210 Iowa Errington (1933) Microtus 1261 Ohio Randie and Austing (1952) Peromyscus 249 Indiana George (1954) Microtus/Sigrnodon 1087 Kansas Rainey and Robinson (1954) Microtus 952 Wisconsin Craighead and Craighead (1956) Microtus 1000 Michigan Stapp (1956) Microtus 2995 Michigan Armstrong (1958) Microtus 2328 Illinois Birkenholz (1958) Microtus 126 Iowa Weller and Fredrickson (1963) Microtus 301 New York Lindberg (1978) Microtus 2112 Iowa Voight and Glenn-Lewin (1978) Microtus 915 Massachusetts Holt and Childs (1991) Open Microtus 3272 Wisconsin Errington (1932) Microtus 199 Michigan Spiker (1933) Perognathus 2821 New Mexico Marti et al. (1986) Microtus 18 956 Montana Holt (unpubl. data) Unknown Microtus 108 Iowa Scott (1948) Microtus 1494 Pennsylvania in Latham (1950) Microtus 2495 Nebraska in Latham (1950) Microtus 1622 Pennsylvania Smith (1984)

Among owls,forest speciestend to have much low- long wings for sustained flight, yet have relatively er aspect ratios than open country species(Nor- low wing loading (Norberg 1990). berg 1987), becauseforaging within vegetation is CONCLUSION favored by those specieswith short wings, large wing area and low wing loading. This enablesthese Is the Long-eared Owl a forest species?These speciesto have slow,maneuverable flight (Norberg data suggestthat the Long-eared Owl may not be 1987). Contrastingthis are open countrymigratory a forest species;however, more forest studies are speciessuch as the Long-eared Owl, Snowy Owl needed. Long-eared Owls obviously depend on and Short-eared Owl (Asioflammeus) which have trees and shrubs for nesting and roosting. In large

Table 4. Breeding seasondiet of Long-earedOwls in North America.

HABITAT DOMINANT GROUP N LOCATION SOURCE

Forest Thomomys 1123 Oregon Bull et al. (1989) Edge Microtus 1935 Michigan Wilson (1938) Microtus 274 Michigan Armstrong (1958) Microtus 153 Oregon Reynolds(1970) Open Microtus 114 Nevada Johnson (1954) Microtus 129 Wyoming Craighead and Craighead (1956) Perognathus 315 Arizona Stophlet (1959) Peromyscus 993 Colorado Marti (1969) Perognathus 171 Washington Knight and Erickson(1977) Peromyscus 346 Idaho Marks and Yensen (1980) Peromyscus/Dipodomys 4208 Idaho Marks (1984) Peromyscus 1000 Idaho Thurow and White (1984) Perognathus/Peromyscus 3977 Idaho Craig et al. (1985) Microtus 3020 Montana Holt (unpubl. data) 184 HOLT VOL. 31, NO. 2 open grasslands or shrubsteppe habitat, Long- To adequately address the questionsconcerning eared Owls nest and roost in predominately shrub- impacts of forestry, research needs to cover longer like vegetation. In smaller openings in forestsand periods of time and must also researchthe species along forest edges adjacent to open areas, Long- year-round.Although many short-term studiespro- eared Owls use trees (often conifers) to nest and vide useful information, they simply cannot pro- roost. Data frmn this review emphasize that per- vide enough data to answerquestions such as those haps too much forest may cause Long-eared Owls addressedherein. Given that Long-eared Owls are to leave an area (Bosakowski et al. 1989b), while migratory and nomadic, and often dependent on patches of open areas within or near forest edges small mammal cycles three to four yr long (e.g., may benefit them. Unfortunately, forest age and voles), studies should at the least cover this dura- stand structure requirements are not known for tion, and preferably several cycles. this species.Thus, the impacts of forest manage- ment cannot be ascertained at this time. Addition- ACKNOWLEDGMENTS ally, tbrest managers may need to define what a I thank Gerald Niemi for the invitation to this sympo- forest owl speciesis. Perhaps the Long-eared Owl sium. This manuscriptbenefited from commentsby Stacy Drasen, Tom Bosakowski, Dan Varland and Gerald Nie- can best be defined as an edge species,when found mi. in or near forest habitats.It may be presumptuous at this point in time to suggestforest-management LITERATURE CITED guidelines regarding the Long-eared Owl, particu- ANDREWS,J.W. 1982. A winter roost of Long-earedOwls. larly since no conclusive data exist pertaining to Bird Observ. East. Mass. 10:13-22. effects of present or past forestry practices. ARMSTRONG,W.H. 1958. Nesting and food habits of the Given the recent interest of metapopulation Long-eared Owl in Michigan. Mich. State Univ. Mus. analysis(Levins 1969), which includes the core-sat- Biol. So:. 1:63-96. ellite (Boorman and Levitt 1973) and sink and BIRKENHOLZ,D. 1958. Notes on a wintering flock of source (Pulliam 1988) models, forest-management Long-eared Owls. Ill. Acad. Sci. Trans.51:83-86. considerations must include results of long-term BLOOM,P.H. 1994. The biology and current statusof the studiesfrom severalgeographic areas. Within these Long-eared Owl in coastalsouthern California. Bull. studies, comparative data of the Long-eared Owl South.Calif. Acad. Sci. 93:1-12. natural history is essentialfor these models to be BOORMAN,S.A. ANDP.R. LEVITT. 1973. Group selection useful. Specifically,the following data are needed: on the boundary of a stablepopulation. Theor.Popul. Biol. 4:85-128. Long-eared Owl residency, mating system,repro- BOSAKOWSKI,T. 1984. Roost selection and behavior of ductive successand home ranges; Long-eared OM the Long-earedOwl (Asiootus) wintering in New Jer- prey speciespopulations, how these effect owl res- sey.Raptor Res. 18:137-142. idency, density and home range and how prey spe- --, R. KANE AND D.G. SMITH. 1989a. Decline of the cies are affected by forest practices; quantitative Long-eared Owl in New Jersey. WilsonBull. 101:481- measures of nest sites; vegetative cover for adult 485. and nestling owl roosting areas; and seasonal use --, R. K•u'•EAND D.G. SMITH. 1989b. Status and man- of habitats because different habitats may be im- agement of Long-eared Owls in New Jersey.Rec. New portant at particular times of the year and avoided JerseyBirds 15:42-46. at other times. BULL, E.L., A.L. WPdGHT AND M.G. I-I•NJUM. 1989. Nest- Therefore, forestry practicesmay have to be stag- ing and diet of Long-eared Owls in conifer forests, gered over spaceand time and perhaps from a few Oregon. Condor91:908-912. to hundreds of kilometers of habitats must be man- CAHN,A.R. ANDJ.T. I•MP. 1930. On the food of certain owls in east-central Illinois. Auk 47:323-328. aged simultaneously or alternately to cover the CmadG,T.H. ANDC.H. TROST.1979. 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