Archived 2010-2011 topics: Black Catbird (Melanoptila glabrirostris): uplist to Vulnerable?

Black Catbird Melanoptila glabrirostris is currently classified as Near Threatened (nearly meeting criteria B1a+bi,ii,iii,v) owing to its moderately small range within which the species is threatened by habitat loss and fragmentation through continuing tourism development, conversion to coconut plantations and periodic hurricanes.

In recent years these threats appear to have led to rapid habitat loss within parts of the range (R. Clay in litt. 2006). If this is thought to have led to population declines of >30% over the past 10 years, the species would warrant uplisting to VU (under criterion A2c). Furthermore, a recent collation of all known localities has found the species’s range to be smaller than previously thought, being restricted to coastal areas of Belize and the Yucatan Peninsula in Mexico, and offshore islands. (B. Miller and C. Miller in litt. 2006). This range is being remapped, and if the resulting Extent of Occurrence covers less than 20,000 km2 and its habitat is severely fragmented and declining the species could qualify as VU (under B1a+biii).

Comments and information on the species likely rate of recent population decline, the extent of its range, and the degree to which its habitat is fragmented would be welcome.

Melanoptila glabrirostris subir a Vulnerable? Melanoptila glabrirostris se clasifica actualmente como Casi Amenazada (casi cumple con los criterios B1a+bi,ii,iii,v), debido a su área de distribución pequeña, dentro de la cual, la especie está amenazada por la pérdida de hábitat y la fragmentación por culpa del desarrollo turístico, la conversión a cocotales y los huracanes periódicos.

En años recientes, parece que estas amenazas han causado una rápida pérdida de hábitat dentro de algunas partes del área de distribución (R Clay in litt 2006). Si se cree que esto ha causado declives en población de >30% durante los últimos 10 años, la especie podría subir a Vulnerable (bajo el criterio A2c). Además, una compilación reciente de todos los registros conocidos de la especie demostró que el área de distribución de la especie es menor que originalmente pensado, siendo restringida a áreas costeras de Belize y la península de Yucatán en México, y otras islas (B Miller y C Miller in litt 2006). Este área de distribución esta siendo mapeado en el momento, y si el EOO resultante es <20,000 km2, y su hábitat severamente fragmentado y en declive, la especies podría calificar bajo VU (B1a+biii).

Comentarios sobre las tendencias poblacionales, el área de distribución y el grado de fragmentación de hábitat bienvenidos.

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2 Responses to Archived 2010-2011 topics: Black Catbird (Melanoptila glabrirostris): uplist to Vulnerable?

  1. Andy Symes says:

    Comments posted as part of 2009 and 2010 updates:

    Ellen McRae (December 2008):
    Hello, list-
    One area historically having a high population of Black Catbirds is Caye Caulker, Belize. I have a 20 yr dataset ancillary to guided birding tours along a route through southern and central areas of the Caye. I have not had the opportunity to evaluate the data however I have noticed recent decline in numbers of Black Catbirds observed during walks through sparsely (yet increasingly) developed littoral forest and thicket at Caye Caulker.

    This habitat is in high demand for not only tourism and cocal but housing development. Such development style, with miniscule lot size, often results in complete habitat removal. Belize Caye Development policy–if actually in effect–grants protection to littoral forest however no law to my knowledge has come of it.
    Best wishes-

    Ellen McRae
    The Siwa-ban Foundation
    PO Box 47
    Caye Caulker
    siwaban@yahoo.com

    Bruce Miller (December 2008):
    There are BCB records that are scattered around in the Yucatan but these I consider these “Accidentals” and are not part of the breeding populations. For example the record form Tikal in the Petén of Guatemala and also Chan Chich Lodge would be such records.

    Only those records considered in the breeding range of the species were used for the mapping evaluation of it’s range.

    Barbara MacKinnon de Montes (December 2008):
    Since Annick Morgenthaler and her professor interviewed me in 2002 for her master thesis on the ecology of the Black Catbird, completed in 2003, I have found small nesting colonies (20 pairs) of the species in the interior of the state of Yucatan, including Hunucmá area, Izamal, Dzonot Carretero etc. This information and many other sightings of the species in the interior of Yucatan and Q.Roo have been published in my seasonal reports for North American Birds. The interior habitat is quite different than that of the east coast, but the species seems quite adaptable. It is unknown where the birds roam during the non-nesting season as most colonies disperse by September. Although I quite agree with the prognosis of the future of the species – being very much related to the deforestation along the region’s east coast, I think it would be worthwhile to research the ecology of the species in the interior of the state of Yucatan, and even perhaps in Q.Roo. However, I think in Q.Roo the use of the interior forest takes place for the most part only during the nesting period. I noted this local “migration” in the late 1970′s, in the formest behind Cancún on the mainland.

    Barbara MacKinnon de Montes
    barbaramackinnonde@gmail.com

    Bruce Miller (December 2008):
    The numbers of individuals had declined precipitously over the past 5 years on Caye Caulker in Belize one of the main strongholds in Belize. As development and habitat loss continues the numbers continue to drop.

    More details will be included in the paper we are working on for Bird Conservation.
    Elevating the status to only VU may not be adequate and the next higher category may be more appropriate.

    Paul A Wood (December 2008):
    Your information suggests that the Black Catbird is confined to coastal habitats in the Caribbean and, were this the case, it might warrant some concern. However, the Black Catbird also breeds in seasonally flooded forest and even deciduous forest at least as far west as north-western Yucatan. I also have records from the Laguna de Terminos in Campeche, and the species is very likely circum-Peninsular in distribution, and probably at least irregular throughout the Yucatan. The species has marked seasonal movements, and more needs to be understood about its migratory patterns before uplisting it. Indeed, since it’s range is clearly much larger than you suggest, it probably should be downlisted. Though Cozumel is frequently hit by hurricanes,the Black Catbird is still one of the most common birds on that island, where it breeds throughout the forested habitats and second growth. Hurricanes do not appear to have had much impact on this species in the past. This situation could change, however, if the frequency and intensity of hurricanes continue to increase, and if this leads to a general degradation of its habitat there. Based on current information, there is no way population declines can even be guessed at.

    Blanca Roldán, a student at the University of Quintana Roo
    has been conducting a study on breeding success in the
    dune habitat of Quintana Roo. She found breeding success
    to be very low, though this is not unusual in tropical
    birds and we have no real way of knowing if the nest checks
    themselves had any effect (also a possibility).

    It seems that breeding was clumped, suggesting that birds
    are not randomly distributed through the habitat. At inland areas
    I have also noted this clumped breeding from year to year
    suggesting a loose colonial set up, and also that breeding areas may be
    traditional. This would be another argument as to their vulnerability.

    Sincerely,

    Paul A. Wood
    Merida, Yucatan, Mexico.

    Robert Curry (December 2008):
    The species remains abundant (even after Hurricane Wilma) in nearly all habitats on Isla Cozumel. Given the island’s size (about 460 km^2), the present population there must number in the tens or hundreds of thousands … but this is a rather restricted piece of the overall limited range. If this species were to be uplisted, it would be logical to uplist also (based on range restriction) the other endemic-but-still-common species on Cozumel: _Chlorostilbon forficatus_ and _Vireo bairdi_.

    Blanca Roldán Clarà (December 2008):
    I have been working this summer 2008 (March-August) in the north coast of Sian Ka´an Biosphere Reserve for my master thesis and we have found interesting data. In our two sites we found very high density of Black Catbirds, 2.18 bird/ha and 10.5 birds/ha. Also, in these sites the most abundant species is the Black Catbird: 45% and 41% of our net captures were black catbirds (with effort of 922 net-hours).
    We were looking for nest, and we found a total of 61 active nests, that were monitored. Using Mayfield (1961, 1975) I calculate daily nest success (survival rate) that has end being extremely low: 0.878, 0.891 and 0.90. Using logistic-exposure (Shaffer 2004) the result has been even lower: 0.801. I don’t think we contributed to the effects of the success of the nest, since we used the standard protocols of nest search and nest monitoring (Ralph et al 1993, Martin & Geupel 1993), but this can be discussed.

    My study area, though it is a Biosphere Reserve, is not absent of deforestation and habitat destruction. All Sian Ka´an coast is private property and in most of the land it is allowed to build some houses, etc. (see Programa de Ordenamiento Ecológico de la Zona Costera de la Reserva de la Biosfera de Sian Ka´an, POET, for more information about it).
    You will be able to find more information about all that when I will finish my thesis, probably next April 2009, or you can contact me. My school is El Colegio de la Frontera Sur, ECOSUR, Chetumal, Quintana Roo.

    Joshua B LaPergola – Department of Biology, Villanova University (March 2009):
    Greetings all!
    From May through July 2008, I worked with Black Catbirds on Isla Cozumel and in the Sian Ka’an Biosphere Reserve (Blanca and I collaborated in Sian Ka’an). At present, I do not have extensive recordings, but one observation I made this past summer was that catbird songs seemed to differ in composition between Cozumel and Sian Ka’an. This observation may suggest cultural drift resulting from decreased or non-existent migration between Cozumel and the mainland. Gene flow between Cozumel and the mainland may therefore also be decreased or non-existent. As part of my research, I collected blood samples from catbirds at both Cozumel and Sian Ka’an, and I will quantify the extent of gene flow between both sites. I will use these results to assess Cozumel’s Black Catbird taxonomic status, as it is currently recognized as an endemic subspecies. I cannot help but wonder what the extent of gene flow is between the mainland and not only Cozumel but the other insular populations of catbirds as well.

    In May 2009, I will return to the Yucatán to resume my study of the catbird’s behavior. I plan to record catbird songs at both sites and fully characterize these differences. Blanca and I also noticed differences between the songs of the catbird population around the Visitors’ Center of Sian Ka’an and the population 30 km south in San Juan. Perhaps the catbirds lend themselves to such cases of differentiation, and we could thus have a number of isolated, unique catbird populations worthy of greater conservation attention.

    Blanca Roldán Clarà (June 2009):
    Hola a todos:
    Another important thing to mention is that we found that black catbird nest distribution seems to be clustered, apparently a common aspect of the bird’s behavior (MacKinnon and Wood, pers. comm.). We (LaPergola and I) are going to verify this phenomenon this summer 2009. If finally the species breeds in a colonial or semi colonial way, it will increase its vulnerability.

  2. I recently made a list of all the interior locations where I and others have located Black Catbirds in the Yucatan Peninsula and came up with 39 different locations (31 in Yucatan from all over the state, 2 Campeche and 6 QR). As I mentioned in a previous comment, I think researchers should concentrate on the ecology of this species in the interior of Yucatan and Campeche, particularly as the species is being forced out of the coastal region along the east coast of the peninsula and Belize.

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