Abstract. DOI: Arctic, Antarctic, and Alpine Research, Vol. 46, No. 4, 2014, pp.

Transcription

1 Arctic, Antarctic, and Alpine Reearch, Vol. 46, No. 4, 2014, pp Evaluating the long-term management of introduced ungulate to protect the palila, an endangered bird, and it critical habitat in ubalpine foret of Mauna Kea, Hawai i Paul C. Banko*+ Steven C. He* Paul G. Scowcroft Chri Farmer Jame D. Jacobi* Robert M. Stephen# Richard J. Camp David L. Leonard Jr.@%^ Kevin W. Brinck J. O. Juvik& and S. P. Juvik& *Pacific Iland Ecoytem Reearch Center, U.S. Geological Survey, P.O. Box 44, Hawai i National Park, Hawai i 96718, U.S.A. Intitute of Pacific Iland Foretry, Pacific Southwet Reearch Station, U.S. Department of Agriculture, Foret Service, 60 Nowelo Street, Hilo, Hawai i 96720, U.S.A. American Bird Conervancy, P.O. Box 44, Hawai i National Park, Hawai i 96718, U.S.A. Hawai i Cooperative Studie Unit, Univerity of Hawai i at Hilo, P.O. Box 44, Hawai i National Park, Hawai i 96718, U.S.A. #Pacific Cooperative Studie Unit, Univerity of Hawai i at Mānoa, 19 Eat Kawili Street, Hilo, Hawai i 96720, of Foretry and Wildlife, Hawai i Department of Land and Natural Reource, 1151 Punchbowl Street, Honolulu, Hawai i 96813, U.S.A. %Pacific Cooperative Studie Unit, Univerity of Hawai i at Mānoa, 1151 Punchbowl Street, Honolulu, Hawai i 96813, U.S.A. ^U.S. Fih and Wildlife Service, 911 NE 11th Avenue, Portland, Oregon 97232, U.S.A. &Department of Geography, Univerity of Hawai i at Hilo, Hawai i 96720, U.S.A. +Correponding author: pbanko@ug.gov Abtract Under the multiple-ue paradigm, conflict may arie when protection of an endangered pecie mut compete with other management objective. To reolve uch a conflict in the Critical Habitat of the endangered Hawaiian honeycreeper, palila (Loxioide bailleui), federal court ordered the eradication of introduced ungulate reponible for damaging the māmane (Sophora chryophylla) foret on which palila depend. During , a total of 18,130 heep (Ovi arie and O. gmelini muimon) and 310 goat (Capra hircu) were removed from Palila Critical Habitat (PCH) primarily by public hunter (54%) and econdarily by aerial hooting. Neverthele, our analyi indicate that ungulate have increaed over time. Palila number have declined harply ince 2003 due to long-term habitat degradation by ungulate and drought. Although culling ungulate population ha allowed ome habitat improvement, their complete removal i neceary for palila to recover, epecially given the potential for continued drought. Introduced predator are being controlled to reduce palila mortality, māmane and other native tree are being planted to retore ome area, and fencing i being contructed to prevent ungulate immigration. Fund are recently available for more effective eradication effort, which are urgently needed to eliminate browing damage in PCH and protect the palila from extinction. DOI: /22 $7.00 PAUL C. BANKO ET AL. / 871

2 Introduction Multiple-ue management of natural area in the Hawaiian Iland often include utained-yield public hunting of introduced large game mammal, which preent a fundamental conflict with the conervation of foret, waterhed, and wildlife. The native biota of oceanic iland are notably vulnerable to the effect of introduced pecie with which they have not co-evolved (Coblentz, 1978; Bowen and Van Vuren, 1997). Herbivorou mammal, which are among the mot conequential of invaive pecie, were not preent in the Hawaiian Iland until their introduction by Wetern explorer beginning in 1778 (Tomich, 1986). The maintenance of game population ha reulted in the wounding and mortality of mature tree by browing and bark-tripping, uppreed foret regeneration, and reduced availability of plant hot to dependent native animal (Scowcroft and Giffin, 1983; Scowcroft and Sakai, 1983; Courchamp et al., 2003). Wetern explorer introduced dometic livetock uch a cattle (Bo tauru), goat (Capra hircu), and heep (Ovi arie) throughout the remote Hawaiian Iland to reupply hip on worldwide voyage (Tomich, 1986). Livetock protected by royal order became feral and proliferated with little predation or competition. Sheep were reported at the ummit of Mauna Kea, the highet peak in the Pacific Ocean, only 32 year after their introduction in 1793, and by 1822, immene herd of wild cattle occupied the area around Mauna Kea (Elli, 1917). Concern for range condition prompted rancher to round up feral cattle by Territorial foreter alo recognized the deforetation caued by feral herbivore in the early 20th century, began fencing a 212-km 2 area of Mauna Kea in 1934, and removed ten of thouand of heep and other ungulate over the next decade (Bryan, 1937a, 1937b, 1947). Management prioritie to enhance game hunting during the mid-20th century, however, allowed heep population to rebound and goat to become abundant, although goat had not been preent on Mauna Kea before 1925 (Bryan, 1927). To further enhance port hunting, European mouflon heep (O. gmelini muimon) were releaed on Mauna Kea during a pure-bred tock and mouflon x feral heep hybrid (Tomich, 1986). The condition of Mauna Kea deteriorated until it wa conidered unutainable for heep, native plant, and a once common bird in the endemic honeycreeper ubfamily (Drepanidinae), the palila (Loxioide bailleui) (Warner, 1960). Palila inhabited about 1300 km 2 of Hawai i Iland when Weterner arrived, but they were once alo ditributed in lowland habitat on Kaua i and O ahu prior to human occupation (Olon and Jame, 1982; Burney et al., 2001; Jame and Olon, 2006). Their range ha ince been reduced to a core area of about 65 km 2 on Mauna Kea due mainly to browing damage to the endemic māmane tree (Sophora chyophylla), whoe eed are the main food of palila (Fig. 1; Banko et al., 2002a; Banko et al., 2013). While cattle converted low-elevation māmane foret to pature, goat and heep degraded high-elevation habitat (Scowcroft, 1983; Scowcroft and Giffin, 1983), retricting the elevation range of māmane foret available to palila (Scott et al., 1984). The palila wa formally lited a an endangered pecie in 1967 by U.S. Fih and Wildlife Service (USFWS, 1967) and i conidered critically endangered internationally (International Union for Conervation of Nature, 2013). Critical Habitat (24,357 ha) wa deignated in 1977 (USFWS, 1977), and additional habitat wa deignated in the pecie recovery plan (USFWS, 2006; Fig. 1.). Palila Critical Habitat (PCH) include land on Mauna Kea between about m elevation, over 98% of which i managed by the Diviion of Foretry and Wildlife (DOFAW), of the Hawai i Department of Land and Natural Reource (HDLNR), a the Mauna Kea Foret Reerve and Ka ohe Game Management Area (USFWS, 1977). Indicating the everity of the pecie conervation tatu, in 2012 the palila occupied jut 27% of PCH (Banko et al., 2013), and the population etimate wa 2176 (95% CI = ), which wa 57% le than the etimate for 1998 (Camp and Banko, 2012). Juvik and Juvik (1984) ummarized the hitory of human activity on Mauna Kea and analyzed planning and management deciion related to palila, concluding that multiple-ue trategie would fail to protect the pecie and that eradication of heep and goat wa the only viable trategy to enure long-term urvival of the palila. They alo reviewed circumtance leading to a federal lawuit and ubequent court order to permanently remove introduced feral heep and goat valued by game hunter from PCH (Appendix). Following the removal by 1982 of virtually all feral heep and feral goat (USFWS, 1986), Juvik et al. (1992) noted improved habitat condition and other (Scowcroft and Conrad, 1988; Scott et al., 1984) alo reported vegetation recovery. Although only mall number of feral heep remained in PCH, mouflon and feral heep hybrid continued to occupy the area (US FWS, 1986) becaue they had been excluded from the original ruling, but in 1987 the court ordered the removal of all Ovi pp. (Pratt et al., 1997; Houck, 2004; Appendix). Decade of tudy have implicated continued unutainable browing by heep within PCH in degradation of the māmane habitat on which the palila depend (Scowcroft, 1983; Scowcroft and Giffin, 1983; Scowcroft and Conrad, 1988; Reddy et al., 2012). The effect of long-term browing have recently been compounded by a evere, prolonged drought, which ha caued the further deterioration of habitat carrying capacity and a harp decline of palila abundance (Banko et al., 2013). Although fence contruction, habitat retoration, and predator control have recently accelerated, palila may repond lowly to improvement due to their retricted diet, low rate of reproduction, and preference for larger, older māmane tree (van Riper et al., 1978; Scott et al., 1984; Pratt et al., 1997; Banko et al., 2009). Thirty year after the analyi of Juvik and Juvik (1984), we recontruct the hitory of ungulate management from unpublihed report and ummarize publihed and unpublihed reearch to evaluate progre in recovering the palila and retoring it habitat. In the ection that follow, we examine whether utained game hunting ha been an effective tool for improving the carrying capacity of PCH or whether it continue to jeopardize palila recovery by delaying, diluting, and perhap thwarting conervation effort. We pecifically analyze the hitory and effectivene of management to remove ungulate from PCH before 1980 and during , a well a the repone of vegetation to ungulate management. We alo conider additional threat to palila and the ubalpine foret ecoytem from other invaive pecie and changing environmental condition. In particular, we evaluate the impact of prolonged drought on population trend of palila and other ympatric foret bird pecie during a recent 14-year period. Additionally, we report on effort to mitigate, manage, and recover habitat for palila and to manage pet and predator. In a ynthei of thee topic, we ae the overall compatibility of long-term multiple-ue management with the recovery propect of palila. Hitory and Evaluation of Ungulate Management MANAGEMENT BEFORE 1980 The detructivene of introduced ungulate to native ecoytem led the territorial government to etablih the foret reerve ytem in Action to protect water, oil, and foret reourc 872 / ARCTIC, ANTARCTIC, AND ALPINE RESEARCH

3 Figure 1. Upper figure how the hitoric range of palila on Mauna Kea, Hualālai, and Mauna Loa volcanoe, Hawai i Iland, with the current ditribution in Critical Habitat; inet how the major Hawaiian Iland. Lower figure how the management juridiction on Mauna Kea. e in the Mauna Kea Foret Reerve were initiated in the 1930 with federal upport through the Civilian Conervation Corp and the aitance of cowboy from ranche that would benefit from a reduction in competition for forage with feral livetock (Bryan, 1937a; Warner, 1960). In 20 month, crew contructed 89 km of tock-proof fence around Mauna Kea in 1937 (Bryan, 1937b). From 1921 to 1946, 13 hore (Equu caballu), 1447 pig (Su crofa), 23 cattle, 797 goat, and 46,765 heep were removed, mot PAUL C. BANKO ET AL. / 873

4 between 1936 and 1946 (Bryan, 1937a, 1947), leading to noticeable habitat recovery (Kramer, 1971). Road and trail built to upport contruction of the foret reerve fence increaed acce for port hunting, and during the 1950 management hifted from waterhed protection to game management (Kramer, 1971). A a reult, the heep population wa allowed to grow through hunting eaon cloure, thereby revering the initial gain in habitat recovery (Warner, 1960). Attempt to maintain a table heep population through the manipulation of hunting eaon and bag limit failed due to oppoition from hunter (Kramer, 1971). Habitat damage caued by the increaing population prompted manager to build tock excloure in 1963 to demontrate to the public the detructive effect of browing. Within a few year of contruction, recovery of vegetation wa marked inide but abent outide the excloure. Even o, attitude and management changed little depite viually dramatic difference in vegetation (Kramer, 1971). The introduction of European mouflon heep further propelled port hunting a the management goal during the 1960 (Kramer, 1971; Tomich, 1986). Eventually, competition for a limited amount of forage among the growing population of feral heep, mouflon, and goat on Mauna Kea became a concern for tate game manager. The relatively mall population of feral pig wa not thought to compete ignificantly with the other game animal. To increae habitat carrying capacity for both mouflon and feral heep, tate wildlife biologit recommended eliminating feral goat, the leat-favored game pecie, and cloely regulating feral heep number (Giffin, 1976). To protect the palila, however, it would be neceary to ubtantially reduce or totally remove all feral heep, becaue even relatively mall number of aggregated heep heavily damaged the habitat (Giffin, 1976). The original palila recovery plan alo recommended the removal of heep (USFWS, 1978). MANAGEMENT AFTER 1980 Depite the management recommendation to reduce population of brower, litigation wa the actual impetu for action to protect PCH (Juvik and Juvik, 1984). Neverthele, the matter wa not imply or quickly reolved and legal battle continue (Appendix). Becaue the condition of the original and ubequent court order till have not been met, the U.S. Ditrict Court and plaintiff continue to evaluate compliance through periodic (uually emiannual) report prepared by HDLNR and ubmitted by the Hawai i attorney general office (HDLNR : tatu report 1 64). Uing information in the HDLNR report, we analyzed the eradication program during three period according to the repone of manager to changing legal mandate. During the firt eight year (Period I: ), only feral heep and goat were targeted for eradication and mouflon heep and hybrid continued to be managed a game pecie. During thi period, feral heep and goat were hot from the air only in 1981, but hunting retriction were eaed to encourage greater public participation. During Period II ( ), which began when the court ordered the eradication of mouflon heep a well a feral heep, public hunting regulation were further liberalized and taff hot from helicopter in 8 of the 11 year, upending aerial hooting during In Period III ( ), helicopter hooting wa conducted at leat emiannually, a tipulated by court order in 1998 (Appendix). Period I ( ) The tate trategy for eradication wa to firt reduce animal number with public hunting before implementing taff hunting to finih the job (HDLNR, 1981: 4th tatu report). Jut eight month before the firt court-ordered deadline (31 July 1981) for eradicating feral heep and goat, the tate expreed confidence in thi approach and expected no eriou problem in complying with the order (HDLNR, 1980: 3rd tatu report): Although public hunting ha been ucceful a a mechanim of feral heep and goat removal on Mauna Kea, it i expected that hunter participation and harvet ucce will decreae a the animal population lower and the remaining heep and goat draw back to more remote area. Therefore, the econd phae of the eradication program; i.e., direct action by the taff of the Department in hooting and removing feral heep and goat, will commence in late January. With the ending of the game bird hunting eaon on weekend a of January 18, 1981, public hunting for heep and goat will be hifted back to Saturday and Sunday. In addition, taff hooting will commence on weekday beginning January 19, 1980 [ic, 1981]. The public hunting eaon will remain open until the eradication i completed or until there i no hunter participation. Staff effort will continue throughout the period and helicopter will be employed if neceary a the time deadline approache. The goal will be to eliminate the lat heep and goat by June 30, 1981, a month prior to the deadline et by the court in order to accommodate any lat minute difficultie or deal with re-invaion of heep or goat from outide the foret reerve. No eriou problem in complying with the court order are anticipated. The State port hunting trategy encompaed a variety of hunting technique, irrepective of their efficacy. To accommodate devotee of archery, handgun, and muzzleloader, a large area of palila core habitat, Ka ohe Game Management Area, continued to be reerved for their excluive ue during mot but not all of the eradication program (HDLNR, 1981: 4th tatu report). Highpowered rifle, the mot effective port hunting tool, were allowed everywhere ele. Neverthele, it wa recognized early that if the hunter-firt trategy wa to ucceed, hunting regulation would need to be liberalized. During Period I, rifle hunting wa allowed over a range of two to even day per week during open eaon, but eaon were typically open for only three to four month each year until 1987, when they were extended to ix month (HDLNR, 1988: 18th tatu report). Before 1980, hunting wa allowed only by lottery (feral heep) or permit (mouflon) on weekend during Augut and September, and bag limit were et (Giffin, 1976, 1981). In September 1979, a pecial four-day eaon wa opened and 279 hunter participated with a 34% ucce rate (animal taken per hunter-trip), which wa conidered lightly above average (HDLNR, 1980: 1t tatu report). In May 1980, hunting wa opened on weekend without a pecial permit or eaonal bag limit but with a daily bag limit of three goat and one heep per hunter (HDLNR, 1980: 2nd tatu report). In 1981, hunting wa extended to four and then even day per week with no daily or eaonal bag limit (HDLNR, 1981: 4th 6th tatu report), but the eaon oon reverted to weekend only due to the ignificant lack of public hunting activity (particularly on weekend) and the neceity to enlit taff hooting in order to continue effective eradication (HDLNR, 1981: 7th tatu report). With increaed hunting opportunitie during June 1980 through October 1982, it wa etimated that 1490 heep were removed during about 4000 hunter-trip, reulting in an overall ucce rate of 37% (HDLNR, 1983: 9th tatu report). Our interpretation of the removal information in the tatu report (Table 1) indicate that 1347 heep were eliminated during , 874 / ARCTIC, ANTARCTIC, AND ALPINE RESEARCH

5 TABLE 1 Number of feral goat and heep (including mouflon and hybrid after 1995) removed from Palila Critical Habitat by public hunter and taff (primarily aerial hooting) during the court-ordered eradication program ( ). Data were derived from unpublihed tatu report ubmitted to U.S. Ditrict Court, Ditrict of Hawai i, by Hawai i Department of Land and Natural Reource (HDLNR : 1t 64th tatu report). Information wa extracted from report narrative when poible due to occaional dicrepancie or inconitencie with information in report table. Sheep Goat Carcae Year Public hunting Aerial/ taff Total removed alvaged Public hunting Aerial/ taff Total removed a a a a a Total , a No aerial hooting; taff hunting wa conducted only on the ground. yielding a lightly lower ucce rate of 34%. Neverthele, thee reult give an indication, which may be overly optimitic given the long eaon cloure, of the efficacy of public hunting a the primary method for eradicating heep. At the time of the July 1981 eradication deadline, aerial urvey detected few remaining feral heep and goat, but movement in and out of PCH through gap in the 44-year-old fence and the warine of the animal made both population etimation and erad- PAUL C. BANKO ET AL. / 875

6 ication problematic (HDLNR, 1981: 7th tatu report). Even o, the State concluded that eradication could be achieved with additional hunting by the public and taff and by repairing or contructing fence to top ingre. In the five year following 1981, no goat and relatively few feral heep were apparently removed from PCH, depite ongoing public hunting and ome fence maintenance (Table 1). The low removal rate during could be interpreted in variou way, but report indicate that few animal were being encountered during ground hunt by the public and taff and that few animal were een during aerial urvey. Alternatively, the low annual harvet could reflect low removal effort, given that public rifle hunting wa cloed for about 30 month from November 1981 into Augut 1985 due to a lack of feral heep and goat to hunt, and hunting wa uually retricted to weekend even during the open eaon (HDLNR, : 9th 13th tatu report). During the ame time, hunting by taff wa conducted epiodically and only on the ground, with only two hunting trip reported during one eight-month period (HDLNR, 1983: 9th tatu report) and periodic hunting at other time, including when other work wa being conducted. Archer, on the other hand, were permitted to hunt on a daily bai within Ka ohe Game Management Area during ome of thi period (HDLNR, 1983: 10th tatu report). Regardle of the factor accounting for the reduced harvet previouly, urpriingly large number of feral heep, mouflon heep, and hybrid heep were eliminated by hunter in 1987 and by helicopter hooting in 1988 a the econd court-impoed eradication deadline, 27 January 1988, approached (Table 1; HDLNR, 1988: 18th tatu report and upplemental report). Jut ahead of the eradication deadline, the eaon for rifle hunting wa increaed from three to ix month and from weekend only to four day a week (HDLNR, 1988: 18th tatu report). Limited effort to control hybrid began in 1986 (HDLNR, 1986: 15th tatu report), but 1987 wa the official tart of the program to eradicate both mouflon and hybrid (HDLNR, 1988: 18th tatu report). Until then, mouflon had been managed a a game pecie. During Period I, only 448 (15%) of the total 2945 feral heep eliminated in PCH (Table 1) were removed by taff in helicopter (about 367) or on the ground (about 72 by hooting, 9 by herding). The nine animal that were herded out of PCH were mouflon/ hybrid heep and apparently fled through one or more gap in the then 49-year-old fence (HDLNR, 1986: 15th tatu report). Staff removed the majority of heep by helicopter hooting in 1981, the year of the firt court-ordered eradication deadline, but they removed none or few in other year. During Period I, taff hunting alo accounted for 21% of the 173 feral goat removed. Period II ( ) Following the harvet of 915 heep, including mouflon and hybrid, by public hunter in 1987 and the elimination of 1154 heep by aerial hooting in 1988, relatively few animal were removed during the remaining 10 year of Period II (Table 1). Staff hot heep from helicopter in 8 of the 11 year, upending aerial control during More than 200 heep were removed by aerial hooting in only one other year (1991) beide Even though the hunting eaon wa lengthened coniderably and bag limit were abolihed, hunter harveted more than 200 heep only in the two final year of the period. In 1988, rifle hunting wa allowed from three to five day per week, and the eaon wa extended from ix to nine month (HDLNR, 1989: 20th tatu report). In the following year, the open eaon wa expanded to five day a week and hunting wa allowed in all month (HDLNR, 1990: 21t [ic] tatu report). To increae the harvet of animal by the public, taff-aited hunt were implemented in 1998 whereby participant hunted a they hiked back to their vehicle after being tranported by taff to location near concentration of heep. Thi program wa quickly abandoned due to low hunter participation and becaue only 15 heep were taken (HDLNR : 37th 40th tatu report). Additionally, information about the ditribution of animal wa made available to hunter by HDLNR taff to increae the efficacy of removal by hunting. In keeping with their effort to expand hunting opportunitie, the State continued to reerve large area of PCH for low-yield hunting method, uch a archery and pitol. Although till not a effective a high-powered rifle, when muzzleloader were allowed into the pecial hunting area in 1997, the harvet rate increaed from 9.7% for archer to 78.3% for muzzleloader (HDLNR, 1998, 1999: 36th and 38th tatu report). Period III ( ) A tipulated by court order in 1998 (Appendix), the State increaed it effort to remove heep from PCH by further liberalizing hunting regulation and more frequent aerial effort. Beginning in 1999, all heep could be hunted even day a week, except during a pecial feral pig hunt in January, March, and April (HDLNR, 1999: 39th tatu report) and during the game bird hunting eaon in November December (HDLNR, 2000: 40th tatu report). Although a large area continued to be reerved for archer and other not uing high-powered rifle, there were no retriction a to the number, age, or ex of the animal taken. Moreover, helicopter miion were conducted at leat emiannually. More than 200 heep were killed by hunter in 8 of the 13 year, wherea aerial hooting removed at leat 200 animal every year (Table 1). AERIAL SHOOTING PROGRAM Helicopter hooting and limited ground removal by taff or contractor accounted for 46% of the 18,130 heep and 55% of the 310 goat removed from PCH (Table 1). The frequency and intenity of helicopter ue varied greatly over the 32-year eradication program. Aerial hooting wa firt ued during 30 day in June and July 1981, a the firt court-ordered eradication deadline approached. Around the time of the econd eradication deadline, 27 January 1988, and in the month that followed, one or two helicopter were deployed daily for 28 helicopter-day (HDLNR, 1988: upplement to 18th tatu report). Helicopter miion in 1981 and 1988 accounted for 45% of all aerial hooting during the entire eradication program. From 1989 to 1994, helicopter ue totaled only 15 day. Helicopter hooting wa upended in 1995 due to funding contraint, and more importantly, the lack of a tate contract for helicopter rental (HDLNR, 1996: 32nd tatu report). Although aerial urvey were reumed in 1996, hooting from helicopter remained upended until late 1998 (HDLNR, : 33rd 38th tatu report). From 1987, when mouflon and hybrid heep were targeted for eradication, to 1998, when helicopter ue reumed after the three-year hiatu, aerial operation accounted for 48% of the 4862 heep removed. Of the 2485 heep removed by taff during thi period, 2343 were hot from the air, 101 were driven out of PCH, 26 were hot by taff on the ground, and 15 were taken by public hunter in taff-aited hunt. Aerial operation during involved a ingle helicopter flown from 2 10 day each year and accounted for 48% of 876 / ARCTIC, ANTARCTIC, AND ALPINE RESEARCH

7 the 11,254 heep removed (Table 1). Of the 136 feral goat eliminated during thi 13-year period, 60% were hot from the air and the remainder wa removed by taff on the ground. Aerial hooting wa conducted for a total of 134 helicopterday in 22 of the 32 year of the eradication program ( ). Since 1988, when annual helicopter operation began, and excluding the hiatu of , the aerial hooting effort averaged 5.2 helicopter-day per year, with the length of a helicopter-day varying due to weather condition and other factor. Although aerial miion have been conducted in all month of the year, mot (64%) occurred during Augut April, when relatively few palila net (Banko et al., 2002a). The wide variation in the number of animal removed annually (Table 1) ugget inconitency in the aerial removal effort. Several factor may have affected the reult of aerial operation, but becaue the level of effort wa not quantified (e.g., animal removed per hour of flight) in State report, inference about removal rate hould be viewed with caution. For example, radio-tagged heep were tracked to locate and remove herd more efficiently during , but no mention of radio-tracking appear in later report. The practice of alvaging carcae and ditributing them to the public began in 1999 and more than 25% of carcae were alvaged annually ince 2000, reducing the efficacy of aerial hooting. Of the 5111 heep hot from the air during , 2627 carcae, or an average of 219 annually (mean = 52%; range = 27% 71%), were hauled by helicopter to acce point for the public to claim (Table 1). HDLNR etimated that alvaging carcae conumed about half of the helicopter flight time (Tummon, 2012), the cot of which wa etimated at approximately $800 per hour. UNGULATE REMOVAL RATES AND STANDING POPULATION Sheep and goat were counted at leat once a year during (except 1995) to evaluate the efficacy of the eradication program, but population total were often le than or imilar to the number of animal removed during the ame time period (HDLNR, 1991: 23rd tatu report). Although population monitoring wa dicontinued after 1999, reult from the earlier count ugget that population were being groly underetimated (ee below for upporting detail). Notwithtanding unreliable urvey reult and ubtantial variation in the removal effort by public and taff hunter, it i noteworthy that the number of animal removed from PCH increaed over time, uggeting that management effort were being overwhelmed by reproduction and perhap alo to ome degree by immigration. Rate of removal increaed over time a the eradication program evolved. During Period I ( ), an average of 56 feral heep wa removed annually by HDLNR taff, motly by hooting from helicopter. After mouflon and hybrid were targeted (Period II, , excluding ), taff removed an average of 309 heep annually. During Period III ( ), when aerial hooting wa conducted at leat emiannually, taff removed an average of 412 heep each year, 33% more than during Period II. Information in the State report i inufficient for identifying the reponible factor, but increaed helicopter hooting may have accounted for at leat ome of the increae in removal from Period II to Period III. It i alo likely that population growth due to reproduction and immigration contributed to the increae. Neverthele, immigration of mouflon and hybrid into PCH wa poible only becaue a population had become etablihed on neighboring land after animal had been driven out through gap in the fence or had dipered there unaided. One gap, for example, extended 8 km along the outhern boundary of PCH (HDLNR, 1983: 10th tatu report). Today, in the aftermath of thi range expanion, herd of animal are commonly een inide and outide of PCH along Saddle Road. The problem of immigration wa demontrated in 2009, when feral goat moved into PCH after having been driven out of the adjacent Pōhakuloa Training Area by U.S. Army manager to protect endangered plant (HDLNR, 2010: 61t tatu report). At leat one goat wa oberved (K. Brinck) a far north a the Pu u Mali area in 2010, uggeting that the animal dipered widely. In repone to thi incurion, ground and aerial hooting by HDLNR taff removed 136 goat from PCH during , more than 20 year after goat were thought to have been eliminated from PCH (HDLNR, : 61t 64th tatu report). The rate of heep removal by public hunter alo increaed ubtantially during Period III of the eradication program. Although hunter claimed an average of 183 heep annually during Period II ( , excluding ), they removed an average of 454 each year during Period III ( ). State report do not allow an analyi of trend in hunting effort during thee two period, but longer open eaon in Period III may have contributed to an increae in the annual harvet. Even o, eradication ha not been achieved depite the annual removal of hundred of heep by the public and hundred more by aerial hooting, indicating that more effective method are needed to achieve thi goal. Moreover, given an average annual increae of 125 animal removed by public hunting and aerial hooting combined (linear regreion: R 2 = 0.66, P < 0.001, ; data not hown), it i likely that the heep population ha been increaing rather than declining ince Some factor that might affect the rate of heep removal are change in the genetic compoition and behavioral characteritic of the population. Over the decade, the population ha hifted from purely feral animal to hybrid dominated by mouflon characteritic (He and Banko, 2011). In 1980, feral heep were etimated to be ix time more abundant than mouflon in PCH (HDLNR, 1980: 2nd tatu report), but by 2006, feral and mouflon heep were no longer being differentiated in State report (HDLNR, 2007: 53rd tatu report). During , when an average of 4251 feral heep wa removed annually for waterhed protection, large herd were rounded up by men afoot or on horeback and killed in holding pen (Bryan, 1947; Kramer, 1971). Depite population fluctuation in the following decade (Tomich, 1986), public hunter alo could expect to encounter large herd of heep whoe predictable behavior made them relatively eay target. In contrat, mouflon heep were found more often in mall band of 2 10 individual with herd ize rarely exceeding 100 (Giffin, 1981). Thu, a feral heep number were initially reduced and the proportion of mouflon and hybrid increaed, the public hunting and aerial hooting trategy that wa developed to take advantage of feral heep aggregation behavior may have become le efficient when applied to mouflon. The apparent increae in the population ince 1999 may have reulted partly becaue method were not adapted to a population that wa becoming progreively dominated by hybrid mouflon. There alo might have been effect from animal learning to avoid helicopter activity and from incorporating carca alvaging into the eradication program. Although heep harvet rate have fluctuated annually over the pat 60 year, data averaged over approximately 10-year period indicate that the minimum population ha conitently numbered in the thouand, a would eem to be the cae even today, a PAUL C. BANKO ET AL. / 877

8 dicued below. The average annual yield of 866 heep from both public hunting and aerial hooting during i imilar to yield jut from public hunting before the eradication program: 735 during , 1201 during , and 852 during (HDLNR, 1980: 1t tatu report). The number of heep removed annually from PCH i indicative of a larger tanding population from which thee removal have been drawn. The tanding population ha not been demographically cloed to emigration or immigration and it range acro the boundary of PCH. Although we do not have ueful ungulate abundance urvey data, we can calculate the minimum ize of the tanding population from etimate of annual population growth rate of mouflon on Mauna Kea and Mauna Loa. Giffin (1981) reported the annual population growth rate for mouflon on Mauna Kea to be 14.7% 16.9%. He et al. (2006) etimated a minimum annual growth rate of 22.1% for unhybridized mouflon at the Kahuku Unit of Hawai i Volcanoe National Park on Mauna Loa. Uing thee etimate, we can determine upper and lower limit for the minimum population of heep capable of withtanding the level of removal that have occurred. It i important to undertand that to utain the ame level of removal, a tanding population with a lower annual growth rate would need to be larger than a population with a higher annual growth rate (Fig. 2). Uing a recent peak in removal a an example, a population of 8507 heep would have been neceary to utain the 1795 removal in 2009, given an annual population growth rate of 22.1%. A population of 12,210 would have been neceary to utain the ame number of removal if the annual population growth rate had been 14.7%. Therefore, during , when the number of removal increaed each year, the population utaining thee removal likely increaed a well (Fig. 2). Population level utaining the oberved number of removal could be lower than the level we project (Fig. 2) if annual growth rate of the Mauna Kea heep population have increaed harply ince the 1980, a might be expected if, for example, hooting wa diproportionately directed at ram, a indicated by Giffin (1981). An additional complication i that increaing immigration rate into PCH from adjacent land might alo be upporting thee harvet rate, although there i no data with which to evaluate thi uppoition. Without regular population urvey, uch increae would go undetected, and without a change in the control effort, the population could continue to grow. Evidence from vegetation tudie, a dicued below, ugget that heep population may have rebounded a the carrying capacity of the habitat increaed, which would have occurred a māmane and other forage pecie regenerated following ungulate removal. In fact, manager recommended increaing hunting preure to reduce the heep population, which they believed would enhance the habitat carrying capacity for game on Mauna Kea (Kramer, 1971; Giffin, 1976, 1981). Maintaining animal number within the utainable limit of the reource available in the habitat ha been a longtanding goal of game manager (Leopold, 1933), but in Hawai i, utaining ungulate population for game hunting, a generally practiced in North America, i incompatible with native ecoytem protection (Lepczyk et al., 2011). SUMMARY OF UNGULATE MANAGEMENT The State original trategy of uing public hunting upplemented with aerial taff hooting to comply with the court order to eradicate heep and goat wa in effect at leat through Decade after the 1988 eradication deadline, public hunting continue to be the primary method ued in PCH to remove all form of heep, which are now commonly thought to be mainly hybrid dominated by mouflon characteritic. Not only ha the public been the primary agent in the eradication effort, accommodation have been made for a variety of hunting method, regardle of their effectivene in culling the heep population. More heep were harveted by public hunting than were removed by aerial hooting in mot year during The number of heep eliminated annually by both public hunting and aerial hooting increaed over time but epecially ince Although population urvey were not conducted to evaluate the effectivene of the eradication effort, the increaing rate of removal ugget an increae in the population from which they were taken. Increaed population growth late in the program would be expected if earlier culling enhanced habitat carrying capacity and effort to remove animal were not increaed. Relaxed hunting regulation and more frequent helicopter hooting ince 1999 may alo explain ome of the increae in the harvet. The heep population ha become dominated by mouflon hybrid, alo uggeting that method adapted for controlling feral heep are le effective at controlling mouflon. Mouflon and hybrid heep dipered and were driven out of PCH, enabling both the pread of thee population to new area and the immigration of animal back into PCH through gap in the fence, which wa only poradically maintained ince it completion in For thee reaon, the longtanding program to remove ungulate by public hunting with upplementary aerial hooting ha fallen far hort of achieving eradication. Figure 2. The number of heep removed annually from Palila Critical Habitat on Mauna Kea and the minimum abundance of heep neceary to utain removal at annual population growth rate of 14.7% and 21.1%. Repone of Vegetation to Ungulate Management Detruction of the vegetation by feral heep wa widepread and extreme by 1936, when a major program wa begun to remove introduced ungulate from the Mauna Kea Foret Reerve (Bryan, 1937a; Hartt and Neal, 1940). The cale of the damage wa uch that by 1960 the condition of the vegetation and oil wa till deperately poor (Warner, 1960), depite the removal of over 61,000 feral heep in the preceding 25 year. Neverthele, māmane can regenerate rapidly following the culling of heep, a wa oberved early during the HDLNR eradication effort (HDLNR, 1980: 1t tatu report) and later, a dicued in the following ection. Evidence preented below ugget that māmane regenerated robutly following the large-cale ungulate removal effort of the 1930 and 878 / ARCTIC, ANTARCTIC, AND ALPINE RESEARCH

9 1940, giving rie to many of the medium and large tree oberved today (Banko and Farmer, 2014). The effect of the widepread regeneration of māmane oberved on Mauna Kea ince 1980 may have enhanced habitat-carrying capacity for ungulate, thereby accelerating population rebound. EXCLOSURE STUDIES NEAR TREE LINE In an attempt to demontrate to hunter that heep were dratically reducing the carrying capacity of the habitat for game population, HDLNR fenced mall plot of habitat to illutrate how native plant would recover if protected from browing (Kramer, 1971). Three heep excloure were built in 1963, three more were added in 1972, and a eventh wa added in The excloure encircled the mountain near tree line where heep browing wa mot intene and were located near main road. The initial repone of vegetation inide and outide the excloure led reearcher to conclude that heep were uppreing native foret regeneration and to predict that reducing or eliminating browing preure would allow native plant to reproduce and etablih depite the inevitable proliferation of introduced plant pecie (Scowcroft and Giffin, 1983). Subequent tudie confirmed the prediction: a the heep population wa culled, māmane and other native vegetation outide the excloure began recovering imilarly to what had been oberved earlier inide the excloure, although at varying rate due to difference among the tudy ite (Scowcroft and Conrad, 1988; Scowcroft and Conrad, 1992; Perry and Giffin, 1998). An evaluation of the long-term repone of the vegetation to the heep control program found that the māmane foret exhibited ubtantial regrowth inide excloure at ome ite, epecially thoe that had been protected for the longet time (Reddy, 2011; Reddy et al., 2012). The cover of māmane tree and native hrub increaed between the 1970 and 1998, but then the rate of increae lowed or declined between 1998 and 2009, apparently due to drought. Māmane height cla ditribution inide excloure indicated that recruitment wa initially high before declining a height hifted toward larger, preumably older ize clae. Recurrent heep browing outide excloure negatively affected māmane canopy denity and poibly tree denity at all ite, a well a māmane condition at ome ite. Evidence of a negative effect of non-native pecie on vegetation recovery wa limited and inconitent over time or among ite, although native pecie eemed relatively uncontrained by pace, given that total plant cover did not exceed 67% and non-native cover did not exceed 40%. Although, the excloure repreented a mall portion of the entire māmane foret, Reddy et al. (2012) concluded that browing wa continuing to affect vegetation recovery outide the excloure. LANDSCAPE-LEVEL VEGETATION RESPONSE Reult of other tudie on the wetern lope of Mauna Kea in the core habitat of the palila (Fig. 1) alo indicated improvement in the regeneration of māmane and other native plant following heep removal in the 1980 and 1990 (He et al., 1999), although recovery wa impeded by alien gra cover. In māmane dominated foret, where gra cover wa mot dene, native plant regeneration wa not a prolific a it wa in mixed māmane-naio (Myoporum andwicene) foret, where gra cover wa le dene. Regeneration of naio, which i the only other abundant native tree in PCH, wa comparatively low, uggeting that māmane would eventually dominate in the abence of continued browing. Preumably naio ha become dominant in a major portion of the outhwetern lope ince the introduction of heep, which prefer māmane over naio for browing (Giffin, 1976, 1981). The ditribution of māmane apling (<2 m height) and tree ( 2 m) varied among tudy ite, indicating uneven recovery due to the intenity of prior browing and degree of gra cover (He et al., 1999). To invetigate foret tructure and compoition within PCH, intenive vegetation urvey were conducted on 504 plot (40 x 40 m) on the wetern lope and around Mauna Kea during (Banko et al., 2009). Palila Report plot Tree ( 2 m height) were widepread, being found in 86% of the plot, but tree cover wa pare, averaging only 19% throughout palila habitat with māmane compriing 7%. Mean māmane denity per plot wa 13.5 tree. Māmane tree height averaged 3.7 m, and 61% of māmane tree were le than 4 m tall. Growth model (Scowcroft and Conrad, 1988) indicated that māmane tree le than 4 m tall were alo le than 25 year old; therefore, nearly two-third of all tree had apparently etablihed within the preceding 25 year. Māmane apling (<2 m height) were found in 91% of plot, but only 38% of plot contained denitie equivalent to at leat 1 apling per 100 m 2. Evidence of browing or bark tripping by heep wa recorded in 219 (43%) plot. Māmane apling denity wa relatively high and browe damage wa relatively low near road and where rifle hunting wa allowed (Fig. 3). Converely, apling denity wa lower and browe damage wa higher away from road and in Ka ohe Game Management Area, where archery hunting wa allowed but rifle hunting wa prohibited. The reduction in browe damage wa mot evident within about 700 m of road in Ka ohe Game Management Area, but the effect extended about 2.5 time farther in the adjacent Mauna Kea Foret Reerve, where rifle hunting wa permitted (Fig. 4). Augmenting the reult of vegetation urvey in the field, the effect of ungulate on tree cover wa tracked over 21 year from aerial photograph taken in 1954, 1965, and 1975 on the wetern lope of Mauna Kea (Scowcroft, 1983). The greatet lo of tree cover wa oberved in the area grazed by cattle, indicating their greater detructivene, but a reduction in cover near tree line wa attributed to browing by heep. Extending that analyi to the preent, atellite image from 1977 and 2011 near tree line on the wetern lope where hunting preure along road ha been relatively high how an increae in māmane tree from natural regeneration and demontration planting project (Fig. 5). The dramatic increae in māmane regeneration in area oon after being protected from browing i a hallmark of vegetation tudie in ubalpine Mauna Kea. For example, eedling denity wa 45 time greater inide than outide the Pu u o Kauha heep excloure only two month after it had been contructed (Scowcroft and Giffin, 1983). Although rate of regeneration have been variable, due motly to ite difference, māmane can reproduce prolifically even under advere environmental condition. During the preceding decade of evere drought, for intance, māmane eedling denitie in 2012 were even time greater in pature from which cattle and heep were excluded for ix year compared to denitie immediately adjacent where heep were preent (Banko et al., 2013). Additionally, eedling urvival wa higher (Krukall-Walli tet, P < 0.07) over a even-month period (December 2011 to July 2012) in thee ame pature (HDLNR, unpublihed data). Other Threat to Palila Habitat A variety of factor in addition to ungulate threaten māmane and other native tree and hrub. Alien grae and other weed are pervaive throughout PCH and reduce the availability of reource PAUL C. BANKO ET AL. / 879

10 Figure 3. Ditribution of māmane apling and browe damage on vegetation urvey plot in a portion of the core palila habitat. Sapling denity wa high and browe damage wa low near road and where rifle hunting wa allowed, reflecting the difficulty of talking game over rough, teep terrain. Sapling denity wa low and browe damage wa high away from road and in Ka ohe Game Management Area, where rifle hunting wa not permitted. The heavy black line delineate the core habitat of palila. Figure 4. Percentage of tree with ungulate damage on a 40-m 40-m plot in relation to the ditance of the plot to the nearet road in the Ka ohe Game Management Area (KGMA), where rifle hunting i prohibited, and in an adjacent portion of Mauna Kea Foret Reerve (MKFR), where rifle hunting i permitted. Generally, habitat condition improved with hunter acce (near road) and where the method of harveting game wa more effective (rifle area). Dot ize i proportional to the number of tree taller than 2 m on the plot (minimum = 1, maximum = 61, mean = 14.04). The line i a locally weighted catterplot moothing (loe mooth) with a pan of 0.75 and degree of 2. through competition and increaed fire rik through the accumula- including 15 highly invaive pecie (Banko and Farmer, 2014). tion of fine fuel. About 69% of the 180 pecie of vacular plant Alien grae poe the mot eriou threat to the ecoytem both found during the vegetation urvey were non-native, in term of competition (William, 1994; He et al., 1999) and 880 / ARCTIC, ANTARCTIC, AND ALPINE RESEARCH

11 Figure 5. Change in māmane tree denity near tree line on the wetern lope of Mauna Kea from 1977 (upper image) to 2011 (lower image). Small, unfenced unit of planted māmane tree (P) are ditributed along the road. A fenced unit of planted māmane tree (E) i hown in the central portion of the lower image. fire rik (Thaxton and Jacobi, 2009). Effort have recently been directed toward eliminating cattered patche of the highly flammable fountain gra (Cenchru etaceu), which uppree native plant and promote fire in region of Hawai i Iland below PCH (Cabin et al., 2000). An alien vine, cape ivy (Delariea odorata), can cover māmane and other native tree and hrub. Although it ha pread lowly over the wetern lope ince 1980 (Jacobi and Warhauer, 1992; Banko et al., 2002b), drought may be curtailing it expanion. Cape ivy wa ignificantly (P < 0.001) aociated with higher tree denity, baed on the vegetation urvey, and it ha not expanded to non-foreted area. The level of threat poed by an herbaceou pecie, fireweed (Senecio madagacarieni), i unknown, but it exploive pread throughout PCH (ee below) demontrate the vulnerability of thi ecoytem to invaion by weed after long-term diturbance by ungulate. Although it ha not yet invaded PCH, gore (Ulex europaeu) occur in dene tand below PCH on the eatern lope of Mauna Kea and would poe a eriou threat to the ubalpine habitat if it moved higher. Fire ha occurred in PCH but perhap le frequently than might be expected, given the abundance of gra and other weedy fuel, the dry climate, and the frequency of human activity. Mot fire during the pat 30 year were man-caued and tarted outide of PCH (Thaxton and Jacobi, 2009). Although rapid uppreion ha kept mot fire mall, the potential for larger one i great. In 1977, before the tart of the heep eradication program, a fire that wa attributed to accidental human ignition wept acro the PAUL C. BANKO ET AL. / 881