Archived 2011-2012 topics: Tufted Jay (Cyanocorax dickeyi): request for information

This discussion was first published on Dec 2 2010 as part of the 2010-2011 Red List update.

Initial deadline for comments: 31 January 2012.

Link to BirdLife species factsheet for Tufted Jay

Tufted Jay Cyanocorax dickeyi is listed as Near Threatened under criterion B1a+b(i,ii,iii,v) on the basis that it has a moderately small range, in which it faces the limited threats of habitat clearance and degradation owing to agricultural encroachment and logging.

The species’s Extent of Occurrence iss estimated at 38,600 km2, which does not approach the threshold for Vulnerable under the B1 criterion; however, the species has been maintained as Near Threatened as a precautionary approach. Partners in Flight estimated the population to number fewer than 50,000 birds (A. Panjabi in litt. 2008), thus the population is placed in the band 20,000-49,999 individuals. Although the terrain in its range probably prevents serious damage to its habitat, the population is suspected to be in decline owing to its susceptibility to forest destruction (Madge and Burn 1993). The species also experiences some hunting pressure (J. M. Lammertink in litt. 1998), the impact of which is not known but is probably low.

Up-to-date information is requested on this species’s likely population size, current trend over 18 years (estimate of three generations) and the severity of threats, to help in the assessment of its status.

Madge, S. and Burn, H. (1993) Crows and jays: a guide to the crows, jays and magpies of the world. Robertsbridge, U.K.: Helm Information.

The following document was sent by Pronatura on 16 February 2012: Cyanocorax dickeyi Pronatura Feb12

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2 Responses to Archived 2011-2012 topics: Tufted Jay (Cyanocorax dickeyi): request for information

  1. In the above summary and the BirdLife species factsheet for Tufted Jay, extent of occurrence is estimated at 38,600 km2. This estimate is much too high. Lammertink et at (1996) on page 51 (PDF page 62) reported finding a significant range extension for Tufted Jay and provided a map of the updated known range of the species. When I measure the new global range from that map I arrive at 10,867 km2 which is only 28% of the estimate BirdLife is working with. I am unaware of any new range extensions discovered since 1996 that could account for the discrepancy.

    Not all of the mapped range in Lammertink et al (1996) would be occupied by Tufted Jay because they tend to occur in humid canyons between 1,350-2,150 m elevation whereas the mapped range includes slopes above and below that elevation range. Furthermore, Google Earth shows that the south of the range includes areas with arid non-forested land unsuitable for the Tufted Jay. Someone should do a GIS analysis to map the potentially occupied area within the range of the bird. For now, if we assume that between 65% and 90% of the mapped range is occupied, between 7,064 km2 and 9,780 km2 could be occupied by home ranges. Figure 1 in Crossin (1967) is a map of 5 adjacent home ranges of Tufted Jay. Drawing a polygon around the 5 territories I arrive at an area of 15.2 km2 , or 3.0 km2 per territory. Dividing occupied range by 3.0 equals 2,324 to 3,217 groups globally. Each group reportedly has two breeding adults and 9.3 ± 4.2 individuals total group size (n=7) (Crossin 1967). So I arrive at a global population of ca. 4,647 to 6,434 breeding adults and a total population of ca. 21,575 to 29,874 individuals.

    BirdLife presents its global population estimate in the Tufted Jay species factsheet as 20,000 to 50,000 mature individuals. I am unsure how mature individuals is defined, or how their proportion in the population is derived from Crossin’s data, but if I take 28% of BirdLife’s estimate (equaling the % difference in our global range estimates) it works out at 5,600 to 14,000 “mature” individuals. Which is in the same ballpark as my result for breeding adults.

    Bottomline: there are probably fewer than 10,000 breeding individuals of Tufted Jay globally.

    As far as population trends, I do not expect steep declines caused by habitat loss through logging because the canyons where this species occur do not see the large scale logging that is prevalent on the higher mesas and ridges. However the Tufted Jay range is in the heart land of the drug producing region of NW Mexico and I expect plots of Cannabis and Papaver scattered through the canyons where this species lives. These plots are created by slash and burn. Still the species may be able to cope which such small scale forest disturbance; it does not seem to be a primary forest specialist. It is probable that the species suffers from some wanton curiosity shooting and catapulting by the people that attend the crops. Such shooting mortality may or may not be compensated by reproduction. In all I expect either stable populations or a slow rate of decline in this species.

    References

    Crossin, R. S. 1967. The breeding biology of the Tufted Jay. Proceedings of the Western Foundation of Vertebrate Zoology.

    Lammertink, M., J.A. Rojas-Tomé, F. M. Casillas-Orona, and R. L. Otto. 1996. Status and conservation of old-growth forests and endemic birds in the pine-oak zone of the Sierra Madre Occidental, Mexico. Verslagen en Technische Gegevens 69:1–89. [Online.] Available at http://dare.uva.nl/record/16867/.

  2. Joe Taylor says:

    Pronatura have sent a document with information on this species, and this can be found just below the forum topic.

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