Tinian Monarch (Monarcha takatsukasae)
Compiled by: Fred Amidon, USFWS, Honolulu, Hawaii, Paul Radley, CNMI DFW, Saipan, and Peter Luscomb, Honolulu Zoo, Honolulu, Hawaii
Order: Passeriformes
Family: Corvidae
Subfamily: Dicrurinae
Tribe: Monarchini
Local or Chamorro Name: Chickurikan Tinian
SPECIES OVERVIEW
Description: The Tinian Monarch is a small (~15cm in length), sexually monomorphic species of the family Monarchidae (Takatsukasa and Yamashina 1931). Underparts are light rufous, with olive brown upper parts, brown wings and tail, white wing bars, and white rump and undertail (Baker 1951).
Distribution: Found only on the island of Tinian, Commonwealth of the Northern Mariana Islands (CNMI), and considered locally common. Peters (1996) suggests that a now extirpated population may have also occurred on Saipan based on museum specimens. Monarchs were also reported on Aguiguan in the early 1950’s but some authorities discount this report as an error (Engbring et al. 1986). Gleise (1945) estimated the population on Tinian after WWII to be approximately 40-50 individuals. The total population reported on Tinian was approximately 60,898, 62,863, and 38,449 individuals in 1982, 1996, and 2008, respectively (Camp et al. 2012).
Habitat: Monarchs use native limestone forest, secondary forest, and tangantangan forest, highest densities of the species occurring in native limestone (USFWS 1996, Camp et al. 2012).
Food and Feeding Habits: Aside from a single observation of a bird eating a small lizard, the Tinian Monarch appears to be entirely insectivorous (Marshall 1949). Although monarchs generally forage singly or in pairs, flocks of 3-5 have been observed. They forage for food by gleaning, probing, hovering, and sallying at mid-level in the forest understory, in shrubs close to the ground, and occasionally on the ground. They perch on relatively slender branches to glean invertebrates from leaf and bark surfaces and tend to forage at mid-level in secondary and tangantangan forest; most foraging occurs at 2-5 meters above ground (USFWS 1996). Marshall (1949) described foraging activity of the species as moving slowly through the foliage, flying after insects, and hovering at the peripheral foliage of the tree. Based on food brought to incubating adult monarchs, prey tends to consist of moths, butterflies, ants, caterpillars, and several long legged insects.
Behavior: Monarchs display a wide range of behavioral responses in and around the nest site ranging from complete passiveness to active aggression (USFWS 1996). Aggressive birds will fly directly from the nest to intercept an intruder. Tinian Monarchs are aggressive towards Collard Kingfishers and Micronesian Starlings throughout most the year. Aerial chases and displays between monarchs and Rufous Fantails can commonly be observed, fantail presence appears to be tolerated overall. Chases and agonistic behavior have not been observed between Bridled White-eyes and monarchs; the species appears to be generally tolerant of other avian species and has been frequently documented foraging within 5-10 m of them.
This species seems generally to tolerate con-specifics and considerable overlap in their home ranges has been noted (USFWS 1996). Flocks of 3-6 have been observed moving quietly through the forest together, but it is unknown if these are family groups. Mated pairs have frequently been seen foraging and traveling within 1-3 meters of one another within their territory during both nesting and non-nesting periods.
Breeding: The Tinian Monarch breeds year round but pronounced seasonality in nesting activity, potentially related to rainfall levels, was noted in a 1994-1995 study (USFWS 1996). The three peaks identified occurred in September, January, and May.
Nesting phrenology among habitat types tends to differ (USFWS 1996). Active nests in one of three stages (building, eggs, or nestlings) were more frequent in limestone forest than secondary forest, and tangantangan forest. Nesting success may also be higher in native forest.
Nesting: Monarch nests are open and cup-shaped and tend to consist of dried Casuarina equisetifolia needles, dried leaves, grasses, vine tendrils, spider webs, and feathers. Both male and female take part in construction. Nests are almost always placed at the juncture of vertically oriented supporting branches in the forest understory. Monarchs have been observed reusing old nests (but most were new) and using material taken from a previous nest (USFWS 1996).
Typical mean Tinian Monarch nest dimensions and substrate data include: inner bowl diameter, 51.6 mm; outer nest diameter, 63.8mm; bowl depth, 29.1 mm; nest height, 67.6mm; nest height from ground, 174.6 cm; nest tree height, 246.0 cm; diameter of tree at breast height, 29.2mm; number of branches supporting the nest, 2.7; distance of nest to trunk, 35.8 cm (USFWS 1996).
Over 60% of the Tinian Monarch nests found (n = 62) occurred in native tree species (USFWS 1996). The tree species that monarchs most commonly nested in were Guamia mariannae, Leucaena leucocephala, Ochrosia mariannensis, Aglaia mariannensis, Ficus tinctoria, Spathodea campanulata (USFWS 1996). However, nests were also found in Cynometra ramiflora, Hibiscus tiliaceus, Lantana camara, Melanolepis multiglandulosa, Premna obtusifolia, Acacia confusa, Pithecellobium dulce, Bauhinia monandra, and unidentified vines (USFWS 1996).
Eggs: Mean clutch size is two with 1-3 eggs being documented. Tinian Monarch eggs are white with pale reddish-brown spots distributed around the surface but generally concentrated at the larger end. Egg length and width were approximately 19.2 mm and 14.4 mm, respectively (USFWS 1996).
Incubation: The incubation period is approximately 15 days and does not begin until after the clutch is complete. Both male and female Tinian Monarchs incubate (USFWS 1996).
Brood Behavior: Once eggs hatch one adult monarch predominately broods while the other brings food to the nest, which is given to both brooding bird and nestlings (USFWS 1996). The sex of the brooding adult is unknown. Brooding decreases as the chicks get older; when they reach five days of age, adults tend to brood less than 50% of the time. Fecal sacs are removed from the nest throughout the nestling period.
Growth and development: Nestlings exhibit light colored skin, blackish bill with a yellow base, and a bright yellow gape. By day nine the young are very active, preening and climbing the rim of the nest with their flight feathers still in sheath. By day 11 nestlings appear fully feathered, with down feathers still around edges of the crown. Fledging occurs at approximately 13 days after which adults feed young for up to eight weeks (USFWS 1996).
Molt: Molting appears to occur after the nesting period in June and July, following the onset of the rainy season (USFWS 1996).
Threats: The primary direct threats to Tinian Monarchs are the loss of native limestone and secondary forest habitats, predation by introduced rats, and disease (e.g., avian pox).
Research Needed: Yet to be determined
Conservation Recommendation: Native forest re-vegetation, predator control, and in-depth
analysis of disease impacts, and reinstating of federal and local protective designations.
Order: Passeriformes
Family: Corvidae
Subfamily: Dicrurinae
Tribe: Monarchini
Local or Chamorro Name: Chickurikan Tinian
SPECIES OVERVIEW
Description: The Tinian Monarch is a small (~15cm in length), sexually monomorphic species of the family Monarchidae (Takatsukasa and Yamashina 1931). Underparts are light rufous, with olive brown upper parts, brown wings and tail, white wing bars, and white rump and undertail (Baker 1951).
Distribution: Found only on the island of Tinian, Commonwealth of the Northern Mariana Islands (CNMI), and considered locally common. Peters (1996) suggests that a now extirpated population may have also occurred on Saipan based on museum specimens. Monarchs were also reported on Aguiguan in the early 1950’s but some authorities discount this report as an error (Engbring et al. 1986). Gleise (1945) estimated the population on Tinian after WWII to be approximately 40-50 individuals. The total population reported on Tinian was approximately 60,898, 62,863, and 38,449 individuals in 1982, 1996, and 2008, respectively (Camp et al. 2012).
Habitat: Monarchs use native limestone forest, secondary forest, and tangantangan forest, highest densities of the species occurring in native limestone (USFWS 1996, Camp et al. 2012).
Food and Feeding Habits: Aside from a single observation of a bird eating a small lizard, the Tinian Monarch appears to be entirely insectivorous (Marshall 1949). Although monarchs generally forage singly or in pairs, flocks of 3-5 have been observed. They forage for food by gleaning, probing, hovering, and sallying at mid-level in the forest understory, in shrubs close to the ground, and occasionally on the ground. They perch on relatively slender branches to glean invertebrates from leaf and bark surfaces and tend to forage at mid-level in secondary and tangantangan forest; most foraging occurs at 2-5 meters above ground (USFWS 1996). Marshall (1949) described foraging activity of the species as moving slowly through the foliage, flying after insects, and hovering at the peripheral foliage of the tree. Based on food brought to incubating adult monarchs, prey tends to consist of moths, butterflies, ants, caterpillars, and several long legged insects.
Behavior: Monarchs display a wide range of behavioral responses in and around the nest site ranging from complete passiveness to active aggression (USFWS 1996). Aggressive birds will fly directly from the nest to intercept an intruder. Tinian Monarchs are aggressive towards Collard Kingfishers and Micronesian Starlings throughout most the year. Aerial chases and displays between monarchs and Rufous Fantails can commonly be observed, fantail presence appears to be tolerated overall. Chases and agonistic behavior have not been observed between Bridled White-eyes and monarchs; the species appears to be generally tolerant of other avian species and has been frequently documented foraging within 5-10 m of them.
This species seems generally to tolerate con-specifics and considerable overlap in their home ranges has been noted (USFWS 1996). Flocks of 3-6 have been observed moving quietly through the forest together, but it is unknown if these are family groups. Mated pairs have frequently been seen foraging and traveling within 1-3 meters of one another within their territory during both nesting and non-nesting periods.
Breeding: The Tinian Monarch breeds year round but pronounced seasonality in nesting activity, potentially related to rainfall levels, was noted in a 1994-1995 study (USFWS 1996). The three peaks identified occurred in September, January, and May.
Nesting phrenology among habitat types tends to differ (USFWS 1996). Active nests in one of three stages (building, eggs, or nestlings) were more frequent in limestone forest than secondary forest, and tangantangan forest. Nesting success may also be higher in native forest.
Nesting: Monarch nests are open and cup-shaped and tend to consist of dried Casuarina equisetifolia needles, dried leaves, grasses, vine tendrils, spider webs, and feathers. Both male and female take part in construction. Nests are almost always placed at the juncture of vertically oriented supporting branches in the forest understory. Monarchs have been observed reusing old nests (but most were new) and using material taken from a previous nest (USFWS 1996).
Typical mean Tinian Monarch nest dimensions and substrate data include: inner bowl diameter, 51.6 mm; outer nest diameter, 63.8mm; bowl depth, 29.1 mm; nest height, 67.6mm; nest height from ground, 174.6 cm; nest tree height, 246.0 cm; diameter of tree at breast height, 29.2mm; number of branches supporting the nest, 2.7; distance of nest to trunk, 35.8 cm (USFWS 1996).
Over 60% of the Tinian Monarch nests found (n = 62) occurred in native tree species (USFWS 1996). The tree species that monarchs most commonly nested in were Guamia mariannae, Leucaena leucocephala, Ochrosia mariannensis, Aglaia mariannensis, Ficus tinctoria, Spathodea campanulata (USFWS 1996). However, nests were also found in Cynometra ramiflora, Hibiscus tiliaceus, Lantana camara, Melanolepis multiglandulosa, Premna obtusifolia, Acacia confusa, Pithecellobium dulce, Bauhinia monandra, and unidentified vines (USFWS 1996).
Eggs: Mean clutch size is two with 1-3 eggs being documented. Tinian Monarch eggs are white with pale reddish-brown spots distributed around the surface but generally concentrated at the larger end. Egg length and width were approximately 19.2 mm and 14.4 mm, respectively (USFWS 1996).
Incubation: The incubation period is approximately 15 days and does not begin until after the clutch is complete. Both male and female Tinian Monarchs incubate (USFWS 1996).
Brood Behavior: Once eggs hatch one adult monarch predominately broods while the other brings food to the nest, which is given to both brooding bird and nestlings (USFWS 1996). The sex of the brooding adult is unknown. Brooding decreases as the chicks get older; when they reach five days of age, adults tend to brood less than 50% of the time. Fecal sacs are removed from the nest throughout the nestling period.
Growth and development: Nestlings exhibit light colored skin, blackish bill with a yellow base, and a bright yellow gape. By day nine the young are very active, preening and climbing the rim of the nest with their flight feathers still in sheath. By day 11 nestlings appear fully feathered, with down feathers still around edges of the crown. Fledging occurs at approximately 13 days after which adults feed young for up to eight weeks (USFWS 1996).
Molt: Molting appears to occur after the nesting period in June and July, following the onset of the rainy season (USFWS 1996).
Threats: The primary direct threats to Tinian Monarchs are the loss of native limestone and secondary forest habitats, predation by introduced rats, and disease (e.g., avian pox).
Research Needed: Yet to be determined
Conservation Recommendation: Native forest re-vegetation, predator control, and in-depth
analysis of disease impacts, and reinstating of federal and local protective designations.