Data Zone
Justification of Red List category
This species qualifies for Near Threatened under Criterion B due to it having a small Extent of Occurrence (EOO) and Area of Occupancy (AOO) as well as a small number of Locations. Additionally it qualifies under Criterion D2 because of the continuing threat of Brown Tree Snakes being introduced in its range. However, robust biosecurity protocols and its existence on four islands greatly reduce the risk of this species becoming Critically Endangered or Extinct in a short period of time.
Population justification
Based on surveys undertaken between 2007-2012, the population is estimated at 16,230 birds (c.10,000 mature individuals), consisting of 9,723 on Saipan (data from 2007 [Camp et al. 2009]), 2,269 on Tinian (data from 2008, [Camp et al. 2012]), 3,383 on Rota (data from 2012 [Camp et al. 2015]) and 855 on Aguijan (data from 2008 [Amidon et al. 2014]). The population on Sarigan remains unquantified but is here considered unlikely to comprise more than 100 mature individuals given the recent establishment of the population there. There is some uncertainty about these populations given the lack of more recent data, and so the population is estimated to number 7,500-12,500 mature individuals, with a best estimate of c.10,000.
Trend justification
The species is precautionarily suspected to be declining. Population estimates in 1982 (see Engbring et al. 1982) compared with more recent estimates suggest that populations on Aguijan and Saipan are stable, but those on Rota and Tinian are declining (or at least declined formerly). More recent data are needed to confirm these trends however, and the self-introduction of birds to Sarigan may indicate that the population may now be stable or increasing. Declines were previously assumed based on the inevitable introduction of Brown Tree Snakes Boiga irregularis, which has not materialised, and forest loss which no longer appears to be ongoing (Global Forest Watch [2021] using data from Hansen et al. [2013] and methods disclosed therein)—consequently, if the species is declining, it remains unclear what the acting threats are.
Restricted to the Northern Mariana Islands (USA) where it occurs on the islands of Saipan, Tinian, Aguijan and Rota. It has been extirpated from Guam. Birds self-established on the island of Sarigan (first detected in 2006) and the population was bolstered by the introduction of ten individuals from Saipan in 2012 with confirmed sightings since (Radley 2012).
This species eats a variety of fruit from the forest canopy (Engbring et al. 1982) particularly from native Ficus spp. and Premna obtusifolia trees. It may also descend to feed in bushes or on the ground, where it takes the fruits of the introduced prostrate vine Momordica charantia (del Hoyo et al. 1997). It is found in a variety of forest types but appears more common in limestone forest (Craig 1996) and do prefer mature native forest (del Hoyo et al. 1997). On Aguijan, it is found in heavily grazed forest and on Tinian in the scrubland of introduced Leucaena trees. It seems to breed all year round with a peak in breeding activity and consequently population size during April-July (Craig 1996). It lays one egg in a nest approximately 2.8 m from the ground (del Hoyo et al. 1997).
The principal threat to this species is the accidental introduction of Brown Tree Snake Boiga irregularis which eradicated the species from Guam. There are now robust biosecurity measures on each of the occupied islands and there is no evidence to suggest that the snakes have already been introduced (Yackel Adams et al. 2021); however, this must be kept constantly monitored and kept under review. Other threats include the spread of introduced plant species, especially Leucaena, habitat destruction and localised hunting (del Hoyo et al. 1997). Climate change may pose a future threat.
Conservation Actions Underway
Efforts continue to prevent the accidental introduction of the Brown Tree Snake Boiga irregularis into the Commonwealth of Northern Mariana Islands (CNMI). Inspections of planes, vessels and cargo are conducted at the airports and seaports on the islands of Saipan, Tinian and Rota as a first line of defence. Snake traps are maintained on fence lines surrounding ports of entry on all three of these islands. Rapid response action to reports of Brown Tree Snakes is coordinated between the CNMI Division of Fish & Wildlife (DFW), the USGS Rapid Response Coordinator and local volunteers. A population of self-colonising birds on Sarigan was supplemented by the introduction of more individuals (Radley 2012). Public education efforts on Saipan, led by Pacific Bird Conservation and AZA zoos, include partnerships with the CNMI Public School System, Northern Mariana College, and the local conservation organization Mariana Islands Nature Alliance (MINA). Programs include: assistance with development of local ecology lesson plans to be formally incorporated into primary school curriculum; hosting Northern Mariana College students as field interns (with stipend); and supporting MINA’s the Bring the Trees Back Campaign. Additionally, educational outreach continues via public presentations at several community event venues and in primary school classrooms (K. Reininger in litt. 2021).
Conservation Actions Proposed
Continuously monitor the population on all islands. Control the spread of of introduced plant species, especially Leucaena. Continue to avoid the introduction of Brown Tree Snake on all islands using robust biosecurity protocols. Establish further protected areas and control development to protect remaining habitat, particularly forest, on Saipan (Liske-Clark 2015). Continue public awareness programmes on Saipan to raise awareness of conservation issues (Radley 2012).
24 cm. Small, mostly green fruit-dove. Rose-red forehead, with the remainder of the head, neck, back and breast being silvery-grey, remaining upperparts green. Underparts mostly green with purple patch in lower breast, and yellow belly patch and undertail coverts. Voice Undescribed.
Text account compilers
Berryman, A., Vine, J.
Contributors
Amidon, F.A., Camp, R., Dahal, P.R., Hawley, N., Holmes, T., Lepson, J., Reininger, K., Roberts, H., Saunders, A. & Wiles, G.
Recommended citation
BirdLife International (2024) Species factsheet: Mariana Fruit-dove Ptilinopus roseicapilla. Downloaded from
https://datazone.birdlife.org/species/factsheet/mariana-fruit-dove-ptilinopus-roseicapilla on 22/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 22/12/2024.