The habitat and status of Spix's Macaw <i>Cyanopsitta spixii</i>

The Rendezvous search problem asks how two noncomunnicating players, who move at unit‐speed after a random placement in the search region (in this article, the line), can minimize their expected meeting time. Baston and Gal () solved a version where each player leaves a marker at his starting point, for example parachutes left after jumping into the search region. Here we consider that one or both players have markers which they can drop at chosen times. When the players are placed facing random directions at a distance D on the line the optimal expected meeting times R are known to be as follows: With no markers, R = 13D/8; with one each dropped at the start, R = 3D/2. Here we show that when only one player has a marker, but it can be dropped at any time, we still have R = 3D/2, obtained by dropping the marker at time D/4. Having both players drop markers at chosen times does not further reduce R. We adopt a new algorithmic approach which first fixes the dropping times and then reduces the resulting problem to a finite one. We also consider evanescent markers, which are detectable for a specified time T after being dropped, modeling pheromone scent markers used by some species in mate search or stain dropped by sailors. From a less theoretical and more practical point of view, we can see our problem as that faced by two hikers who get separated when they are walking not too far from a coast. A reasonable Rendezvous strategy is for each of them to head in the general direction of the coastline. On reaching the sea, they can calculate (based on their speed and time taken to reach to coast) the maximum distance along the coastline where the other one arrives. Then they can use our solution, taking that distance as our parameter D. Of course if it turns out that they reached the sea at points closer than D, their Rendezvous time will only be shorter. So our solution can be interpreted as a worst case expected meeting time. The marker might be a note scribbled on the sand, or a pile of rocks. Perhaps before getting separated they would have decided which roles (I or II) each would take up, being careful and cautious hikers. So in particular the hiker taking the role of the marker placer would put down a marker of some sort when he had walked along the coast one quarter the maximum distance to his partner. If the other finds it, he would know for sure the direction of the hiker who dropped it. Another thing to take away from this article is our result that says “two markers are not better than one.” This observation has some significance in the mate search context, where males and females use pheromone deposits to help find each other. In most species, it is only the females who can make such deposits, and the males can detect it. Giving both species the depositing facility would be more costly in terms of energy and, given our negative result, might not significantly reduce Rendezvous times. So in a speculative sense, our result has some explanatory value in this context.

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“…They were later seen flying together, having successfully Rendezvoused. See Griffiths and Tlwarl (1995) and Juniper and Yamashita (1991).…”

Section: Discussionmentioning

confidence: 99%

Rendezvous search with markers that can be dropped at chosen times

Leone

Alpern

2018

Naval Research Logistics

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“…The most dramatic example of this process is Spix's Macaw ( Cyanopsitta spixii ), a species that is virtually extinct in the wild and precarious in captivity ( Juniper & Yamashita 1991). This species probably always occurred at low density and was limited to highly vulnerable riparian forests (Forshaw 1989; Juniper & Yamashita 1991). Once Spix's Macaw became rare in the wild, the demand from wealthy collectors for captive birds intensified to the extent that prices reached at least $20,000 per individual ( Fitzgerald 1989; Clubb 1992).…”

Section: Discussionmentioning

confidence: 99%

Nest Poaching in Neotropical Parrots

Wright¹,

Toft

Enkerlin‐Hoeflich

et al. 2001

Conservation Biology

195

129

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Although the poaching of nestlings for the pet trade is thought to contribute to the decline of many species of parrots, its effects have been poorly demonstrated. We calculated rates of mortality due to nest poaching in 23 studies of Neotropical parrots, representing 4024 nesting attempts in 21 species and 14 countries. We also examined how poaching rates vary with geographic region, presence of active protection programs, conservation status and economic value of a species, and passage of the U.S. Wild Bird Conservation Act. The average poaching rate across all studies was 30% of all nests observed. Thirteen studies reported poaching rates of ≥20%, and four reported rates openface> 70%. Only six studies documented no nest poaching. Of these, four were conducted on islands in the Caribbean region, which had significantly lower poaching rates than the mainland Neotropics. The other two studies that showed no poaching were conducted on the two species with the lowest economic value in our sample ( U.S. retail price). In four studies that allowed direct comparison between poaching at sites with active nest protection versus that at unprotected sites, poaching rates were significantly lower at protected sites, suggesting that active protection efforts can be effective in reducing nest poaching. In those studies conducted both before and after the passage of the U.S. Wild Bird Conservation Act, poaching rates were found to be significantly lower following its enactment than in the period before. This result supports the hypothesis that the legal and illegal parrot trades are positively related, rather than inversely related as has been suggested by avicultural interests. Overall, our study indicates that poaching of parrot nestlings for economic gain is a widespread and biologically significant source of nest mortality in Neotropical parrots.

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“…Only one wild bird exists, known to be a J by DNA sexing of its moulted feathers (Griffiths & Tiwari, 1995). Its caraiba Tahehuia caraiha woodland habitat has suffered longterm destruction and has always been a small and scarce habitat within the more widespread caatinga woodland and scrub of the dry to semi-arid region of northeast Brazil (Juniper & Yamashita, 1991). However, the trapping of adult birds was the most significant factor in the final population decline of the species (Collar et al, 1992).…”

Section: Spix's Macuw Brazilmentioning

confidence: 99%

Parrot conservation and Loro Parque Fundacion, Puerto de la Cruz

Waugh

2000

International Zoo Yearbook

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Loro Parque Fundación (LPF), a non‐governmental organization created in 1994, maintains the largest parrot collection in the world and is a major supporter of international efforts to conserve threatened parrots and their habitats. The collection, comprising approximately 2750 specimens from 310 taxa, is an educational resource which also provides opportunities for research aimed at improving husbandry techniques. LPF supports field research projects designed to integrate the needs of both people and parrots through local community participation and education programmes and a number of these are described here. Data compiled from field research and captive populations are also used to facilitate production of global management plans. In addition, LPF supports research at other institutions into diseases which are a major threat to wild and captive birds: a diagnostic test for psittacine beak and feather disease and a vaccine against polyoma‐virus have already been developed by the Psittacine Disease Research Group, Georgia. The support provided for projects involving the zoo community, avi‐culturists, field researchers and local communities, as well as basic research is described here hiehliahtine the key role LPF plays in encouraging effective collaboration for conservation of parrots in their natural habitat.

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The habitat and status of Spix's Macaw Cyanopsitta spixii

Cited by 11 publications

References 2 publications

Rendezvous search with markers that can be dropped at chosen times

Rendezvous search with markers that can be dropped at chosen times

Nest Poaching in Neotropical Parrots

Parrot conservation and Loro Parque Fundacion, Puerto de la Cruz

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