... 1800 170'W 160I 30'rT-30 N N Kure Midway Pearl and Hermes Reef L siawnskl LI sy a n... more ... 1800 170'W 160I 30'rT-30 N N Kure Midway Pearl and Hermes Reef L siawnskl LI sy a na k n * Loyson Gardner Pinnacl es French Frigate Shoals *Ned er N h KAUAI Niihau,, OAHU Kaula * A MOLOKAI Lanai %* MAUI 20c Ka hoolawe _20 HAWAI I 1 80 170 W 160 FIG. ...
Population size reductions are usually expected to result in decreases of within-population genet... more Population size reductions are usually expected to result in decreases of within-population genetic variation. We here report on allozyme variation in (1) the endemic population of the Laysan finch (Telespiza cantans) that was reduced by a major population crash during the early 1900s and (2) translocated populations on three islets of a distant atoll (Pearl & Hermes Reef). These populations resulted from the introduction of 108 birds to one islet in 1967 and subsequent dispersal to the other islets. Variation in 33 allozyme loci on Laysan was found to be lower than the average in avian populations, matching theoretical expectation. Unexpectedly, the average heterozygosity of Pearl & Hermes populations is higher than at Laysan, and significantly so for two of five polymorphic loci. Variation in allele frequencies is relatively high for avian populations (FST= 0.049), both among the islets of P& H, and between P& H and Laysan. This suggests that isolation within the tiny, translocated populations has resulted in a significant level of genetic differentiation during a relatively short time period (less than 20 years).
From 1986 to 1988 the breeding biology of an endangered Hawaiian honeycreeper, the Laysan Finch (... more From 1986 to 1988 the breeding biology of an endangered Hawaiian honeycreeper, the Laysan Finch (Telespiza cantans), was studied on the coral island of Laysan in the Hawaiian Archipelago. Laysan Finches are apparently monogamous. Pairs defend mates and nest sites, but not feeding territories. Only the female constructs the nest and incubates. The breeding season is prolonged, but there is yearly variation in onset. Pairs can have more than one clutch per year. The average clutch size was 3.19 eggs. The modal incubation period was 16 days. Onethird of all eggs laid disappeared, probably due primarily to intraspecific predation. Eggs hatched asynchronously in the order laid. Chicks fledged at 22-26 days of age, and were dependent for at least three additional weeks. Weather affected reproductive success. A severe storm in 1986 caused almost total mortality of eggs and chicks, regardless of clutch size. Later in that same year, fledglings per nest increased as clutch size increased. During the dry 1987 field season, the onset ofbreeding was delayed, mean egg weight decreased, the number of malformed eggs increased, and clutches tended to be smaller. Although in good years four-egg clutches produced more fledglings per nest than smaller clutches, in poorer years three-egg clutches produced at least as many or more fledglings per nest than larger clutches. In this fluctuating environment, a modal clutch size of three apparently has been selected for, possibly because it yields the highest average number of offspring per nest during both good and poor years.
The typical Iaysan Finch (Telespiza cantans) nest on Iaysan Island is composed primarily of the b... more The typical Iaysan Finch (Telespiza cantans) nest on Iaysan Island is composed primarily of the bunchgrass Eragrostis variabilis, and is hidden from view within a bunchgrass clump. About one-third of the nests have two or more plants species in the nest substrate and canopy. Nests are usually in the lower two-thirds of the bunchgrass clump, and in the lee of the prevailing winds. The dimensions of nests and nest substrates were compared between the predominant vegetation associations: bunchgrass and viney. Almost all nests occurred in these two associations. Nests in the bunchgrass association had more of their canopies composed of a single plant species, had substrates with greater maximum heights, had more cover over the nest cups, and had wider outer nest diameters. Nine other nest and nest substrate variables showed no difference between the two vegetation types, nor did clutch size and fledging success differ significantly, although evidence suggested that fledging success may differ for early (or late) season nesters. Nearest-neighbor distances of simultaneously active nests were larger in the bunchgrass association than in the viney, and nest densities were approximately half. Nests were relatively more aggregated in the viney association. The viney association occupies half as much total area as the bunchgrass association, but it appears to be the most productive per unit area for nesting. The rapid invasion over the past 29 years by a non-native bush (Pluchea indica) into this important vegetation association warrants further study into the possibility of vegetation control.
Historical and demographic data were used in a computer model tosimulate neutral genetic change i... more Historical and demographic data were used in a computer model tosimulate neutral genetic change in populations of the Laysanfinch (Telespiza cantans), an insular passerine bird that hasundergone documented founder events at Pearl and Hermes reef(PHR). Measures of genetic variation in the natural PHRpopulations generally matched those in the simulated populations,except that heterozygosity on Southeast Island was lower than themodel predicted,
The population of an endangered, endemic Hawaiian honeycreeper, the Laysan Finch Telespiza cantan... more The population of an endangered, endemic Hawaiian honeycreeper, the Laysan Finch Telespiza cantans, has been censused over 23 years using strip transects. During 1986-1988, multiple censuses were made. Vegetation type, breeding cycle stage, and variability among individual counters influenced the transect counts during those three years. During the breeding peak, the population appeared to be undercounted (presumably because females were not seen) and was most evenly distributed throughout the major vegetation types. Variability among individual counters was significant, but was not explained by previous census experience. The breeding season population estimate declined by one-half in the year following a drought. There was no overall population trend over the 23 years. Major refinement of census techniques would be difficult to justify due to logistic constraints and the need to minimize ecosystem damage. We conclude that strip transects are adequate for monitoring gross changes in this population, especially if breeding stage is known.
Sixteen bird species were detected during four surveys made during 1992 and 1993. Two of the spec... more Sixteen bird species were detected during four surveys made during 1992 and 1993. Two of the species (12%) were indigenous migratory shorebirds and the other fourteen (88%) were introduced non-native species. The paucity of indigenous avifauna and the complete absence of endemic species can be attributed directly or indirectly to human influences.
... Page 2. Page 3. Order Num.ber 9129695 The breeding ecology of the Laysan finch (Drepanidinae:... more ... Page 2. Page 3. Order Num.ber 9129695 The breeding ecology of the Laysan finch (Drepanidinae: Telespiza cantans) on Laysan Island Morin, Marie Patricia, Ph.D. University of Hawaii, 1991 V·M·I 300N. Zeeb Rd. Ann Arbor, MI48106 Page 4. Page 5. ...
Twenty-five bird species were detected at fifty-one count stations located along seven transects ... more Twenty-five bird species were detected at fifty-one count stations located along seven transects in Kaloko-Honok6hau National Historical Park. Each station was counted once during fall-winter (October and November 1992) and once again during springsummer (April and May 1993). Significantly more species per station were detected during the spring counts, but there was no difference in the mean numbers of birds detected per station when the two count periods were compared. Nine of the bird species (36%) were indigenous waterbirds or shorebirds and the other 16 species (64%) were introduced, non-native species. Two of the three indigenous waterbirds are also endemic and endangered. As expected, the bird checklist for Kaloko-Honok6hau contains many more species than those detected during the two short-term censuses. The relatively high species diversity can be attributed to the large amount of wetland (primarily brackish water fishponds with associated marshy areas and anchialine pools) and sandy shoreline available within the park. Like other lowland sites, the high percent of non-native bird species is attributable to centuries of direct or indirect human impact.
Waterbird and shorebird species and relative abundance from complete counts made at 'Aimakapa Fis... more Waterbird and shorebird species and relative abundance from complete counts made at 'Aimakapa Fishpond (AP: n = 168), Kaloko Fishpond (KP: n = log), and the shoreline south of 'Aimakapa Beach to the southern edge of the rocky shore adjacent to 'Ai'opio Fishtrap (SA: n =
The Tahiti Petrel, Pterodroma rostrata (Chesser et al. 2011) or Pseudobulweria rostrata (Bretagno... more The Tahiti Petrel, Pterodroma rostrata (Chesser et al. 2011) or Pseudobulweria rostrata (Bretagnolle et al. 1998, Birdlife International 2012, Howell 2012, Dickinson and Remsen 2013), breeds in the Society and Marquesas islands, New Caledonia, and other islands in the South Pacific Ocean (Villard et al. 2006). It ranges widely in the tropical central Pacific and is considered a nonbreeding vagrant in Hawaiian waters (Pyle and Pyle 2017). Three of this species’ close relatives of the genus Pseudobulweria are “critically endangered,” and the Tahiti Petrel itself is listed as “near threatened” on the Red List of the International Union for Conservation of Nature (Birdlife International 2012). The Tahiti Petrel is very similar in appearance to the endangered Phoenix Petrel (Pterodroma alba), which has made it difficult to establish the Tahiti Petrel’s distribution in the north-central Pacific (King 1970, Spear et al. 1992, 1999, Spear and Ainley 1998, BirdLife International 2016). Early...
Sixteen bird species were detected during four surveys made during 1992 and 1993. Two of the spec... more Sixteen bird species were detected during four surveys made during 1992 and 1993. Two of the species (12%) were indigenous migratory shorebirds and the other fourteen (88%) were introduced non-native species. The paucity of indigenous avifauna and the complete absence of endemic species can be attributed directly or indirectly to human influences.
... Page 2. Page 3. Order Num.ber 9129695 The breeding ecology of the Laysan finch (Drepanidinae:... more ... Page 2. Page 3. Order Num.ber 9129695 The breeding ecology of the Laysan finch (Drepanidinae: Telespiza cantans) on Laysan Island Morin, Marie Patricia, Ph.D. University of Hawaii, 1991 V·M·I 300N. Zeeb Rd. Ann Arbor, MI48106 Page 4. Page 5. ...
... 1800 170'W 160I 30'rT-30 N N Kure Midway Pearl and Hermes Reef L siawnskl LI sy a n... more ... 1800 170'W 160I 30'rT-30 N N Kure Midway Pearl and Hermes Reef L siawnskl LI sy a na k n * Loyson Gardner Pinnacl es French Frigate Shoals *Ned er N h KAUAI Niihau,, OAHU Kaula * A MOLOKAI Lanai %* MAUI 20c Ka hoolawe _20 HAWAI I 1 80 170 W 160 FIG. ...
Population size reductions are usually expected to result in decreases of within-population genet... more Population size reductions are usually expected to result in decreases of within-population genetic variation. We here report on allozyme variation in (1) the endemic population of the Laysan finch (Telespiza cantans) that was reduced by a major population crash during the early 1900s and (2) translocated populations on three islets of a distant atoll (Pearl & Hermes Reef). These populations resulted from the introduction of 108 birds to one islet in 1967 and subsequent dispersal to the other islets. Variation in 33 allozyme loci on Laysan was found to be lower than the average in avian populations, matching theoretical expectation. Unexpectedly, the average heterozygosity of Pearl & Hermes populations is higher than at Laysan, and significantly so for two of five polymorphic loci. Variation in allele frequencies is relatively high for avian populations (FST= 0.049), both among the islets of P& H, and between P& H and Laysan. This suggests that isolation within the tiny, translocated populations has resulted in a significant level of genetic differentiation during a relatively short time period (less than 20 years).
From 1986 to 1988 the breeding biology of an endangered Hawaiian honeycreeper, the Laysan Finch (... more From 1986 to 1988 the breeding biology of an endangered Hawaiian honeycreeper, the Laysan Finch (Telespiza cantans), was studied on the coral island of Laysan in the Hawaiian Archipelago. Laysan Finches are apparently monogamous. Pairs defend mates and nest sites, but not feeding territories. Only the female constructs the nest and incubates. The breeding season is prolonged, but there is yearly variation in onset. Pairs can have more than one clutch per year. The average clutch size was 3.19 eggs. The modal incubation period was 16 days. Onethird of all eggs laid disappeared, probably due primarily to intraspecific predation. Eggs hatched asynchronously in the order laid. Chicks fledged at 22-26 days of age, and were dependent for at least three additional weeks. Weather affected reproductive success. A severe storm in 1986 caused almost total mortality of eggs and chicks, regardless of clutch size. Later in that same year, fledglings per nest increased as clutch size increased. During the dry 1987 field season, the onset ofbreeding was delayed, mean egg weight decreased, the number of malformed eggs increased, and clutches tended to be smaller. Although in good years four-egg clutches produced more fledglings per nest than smaller clutches, in poorer years three-egg clutches produced at least as many or more fledglings per nest than larger clutches. In this fluctuating environment, a modal clutch size of three apparently has been selected for, possibly because it yields the highest average number of offspring per nest during both good and poor years.
The typical Iaysan Finch (Telespiza cantans) nest on Iaysan Island is composed primarily of the b... more The typical Iaysan Finch (Telespiza cantans) nest on Iaysan Island is composed primarily of the bunchgrass Eragrostis variabilis, and is hidden from view within a bunchgrass clump. About one-third of the nests have two or more plants species in the nest substrate and canopy. Nests are usually in the lower two-thirds of the bunchgrass clump, and in the lee of the prevailing winds. The dimensions of nests and nest substrates were compared between the predominant vegetation associations: bunchgrass and viney. Almost all nests occurred in these two associations. Nests in the bunchgrass association had more of their canopies composed of a single plant species, had substrates with greater maximum heights, had more cover over the nest cups, and had wider outer nest diameters. Nine other nest and nest substrate variables showed no difference between the two vegetation types, nor did clutch size and fledging success differ significantly, although evidence suggested that fledging success may differ for early (or late) season nesters. Nearest-neighbor distances of simultaneously active nests were larger in the bunchgrass association than in the viney, and nest densities were approximately half. Nests were relatively more aggregated in the viney association. The viney association occupies half as much total area as the bunchgrass association, but it appears to be the most productive per unit area for nesting. The rapid invasion over the past 29 years by a non-native bush (Pluchea indica) into this important vegetation association warrants further study into the possibility of vegetation control.
Historical and demographic data were used in a computer model tosimulate neutral genetic change i... more Historical and demographic data were used in a computer model tosimulate neutral genetic change in populations of the Laysanfinch (Telespiza cantans), an insular passerine bird that hasundergone documented founder events at Pearl and Hermes reef(PHR). Measures of genetic variation in the natural PHRpopulations generally matched those in the simulated populations,except that heterozygosity on Southeast Island was lower than themodel predicted,
The population of an endangered, endemic Hawaiian honeycreeper, the Laysan Finch Telespiza cantan... more The population of an endangered, endemic Hawaiian honeycreeper, the Laysan Finch Telespiza cantans, has been censused over 23 years using strip transects. During 1986-1988, multiple censuses were made. Vegetation type, breeding cycle stage, and variability among individual counters influenced the transect counts during those three years. During the breeding peak, the population appeared to be undercounted (presumably because females were not seen) and was most evenly distributed throughout the major vegetation types. Variability among individual counters was significant, but was not explained by previous census experience. The breeding season population estimate declined by one-half in the year following a drought. There was no overall population trend over the 23 years. Major refinement of census techniques would be difficult to justify due to logistic constraints and the need to minimize ecosystem damage. We conclude that strip transects are adequate for monitoring gross changes in this population, especially if breeding stage is known.
Sixteen bird species were detected during four surveys made during 1992 and 1993. Two of the spec... more Sixteen bird species were detected during four surveys made during 1992 and 1993. Two of the species (12%) were indigenous migratory shorebirds and the other fourteen (88%) were introduced non-native species. The paucity of indigenous avifauna and the complete absence of endemic species can be attributed directly or indirectly to human influences.
... Page 2. Page 3. Order Num.ber 9129695 The breeding ecology of the Laysan finch (Drepanidinae:... more ... Page 2. Page 3. Order Num.ber 9129695 The breeding ecology of the Laysan finch (Drepanidinae: Telespiza cantans) on Laysan Island Morin, Marie Patricia, Ph.D. University of Hawaii, 1991 V·M·I 300N. Zeeb Rd. Ann Arbor, MI48106 Page 4. Page 5. ...
Twenty-five bird species were detected at fifty-one count stations located along seven transects ... more Twenty-five bird species were detected at fifty-one count stations located along seven transects in Kaloko-Honok6hau National Historical Park. Each station was counted once during fall-winter (October and November 1992) and once again during springsummer (April and May 1993). Significantly more species per station were detected during the spring counts, but there was no difference in the mean numbers of birds detected per station when the two count periods were compared. Nine of the bird species (36%) were indigenous waterbirds or shorebirds and the other 16 species (64%) were introduced, non-native species. Two of the three indigenous waterbirds are also endemic and endangered. As expected, the bird checklist for Kaloko-Honok6hau contains many more species than those detected during the two short-term censuses. The relatively high species diversity can be attributed to the large amount of wetland (primarily brackish water fishponds with associated marshy areas and anchialine pools) and sandy shoreline available within the park. Like other lowland sites, the high percent of non-native bird species is attributable to centuries of direct or indirect human impact.
Waterbird and shorebird species and relative abundance from complete counts made at 'Aimakapa Fis... more Waterbird and shorebird species and relative abundance from complete counts made at 'Aimakapa Fishpond (AP: n = 168), Kaloko Fishpond (KP: n = log), and the shoreline south of 'Aimakapa Beach to the southern edge of the rocky shore adjacent to 'Ai'opio Fishtrap (SA: n =
The Tahiti Petrel, Pterodroma rostrata (Chesser et al. 2011) or Pseudobulweria rostrata (Bretagno... more The Tahiti Petrel, Pterodroma rostrata (Chesser et al. 2011) or Pseudobulweria rostrata (Bretagnolle et al. 1998, Birdlife International 2012, Howell 2012, Dickinson and Remsen 2013), breeds in the Society and Marquesas islands, New Caledonia, and other islands in the South Pacific Ocean (Villard et al. 2006). It ranges widely in the tropical central Pacific and is considered a nonbreeding vagrant in Hawaiian waters (Pyle and Pyle 2017). Three of this species’ close relatives of the genus Pseudobulweria are “critically endangered,” and the Tahiti Petrel itself is listed as “near threatened” on the Red List of the International Union for Conservation of Nature (Birdlife International 2012). The Tahiti Petrel is very similar in appearance to the endangered Phoenix Petrel (Pterodroma alba), which has made it difficult to establish the Tahiti Petrel’s distribution in the north-central Pacific (King 1970, Spear et al. 1992, 1999, Spear and Ainley 1998, BirdLife International 2016). Early...
Sixteen bird species were detected during four surveys made during 1992 and 1993. Two of the spec... more Sixteen bird species were detected during four surveys made during 1992 and 1993. Two of the species (12%) were indigenous migratory shorebirds and the other fourteen (88%) were introduced non-native species. The paucity of indigenous avifauna and the complete absence of endemic species can be attributed directly or indirectly to human influences.
... Page 2. Page 3. Order Num.ber 9129695 The breeding ecology of the Laysan finch (Drepanidinae:... more ... Page 2. Page 3. Order Num.ber 9129695 The breeding ecology of the Laysan finch (Drepanidinae: Telespiza cantans) on Laysan Island Morin, Marie Patricia, Ph.D. University of Hawaii, 1991 V·M·I 300N. Zeeb Rd. Ann Arbor, MI48106 Page 4. Page 5. ...
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