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COSEWIC Assessment and Status Report on the Yellow Rail in Canada
- Assessment Summary
- Executive Summary: from the 1999 Status Report
- COSEWIC Mandate, Membership and Definitions
- Lists of Figures and Tables
- Species Information
- Population Size and Trend
- Summary of Population Size, Number of Breeding Localities and Trends
- General Biology
- Limiting Factors
- Special Significance of the Species
- Evaluation and Proposed Status
- Technical Summary
- Acknowledgements, Biographical Summary of the Authors, and Literature Cited
The Yellow Rail’s biology was recently summarized by Bookhout (1995). Most of what is known about the nesting behaviour comes from Stalheim (1974, 1975), who studied birds in semi-captivity, and Stenzel (1982), who radio-tracked breeding birds in northern Michigan. Several publications have appeared since Bookhout (1995) (e.g. Robert et Laporte 1997, Robert et al., 1997) and others based on work from Québec (M. Robert and P. Laporte), New-Brunswick (G. Forbes and P. Kehoe), Oregon (M. Stern and K. Popper) and Texas (K. Mizell and D. Slack) should appear soon.
Yellow Rails probably start breeding when they are a year old. Pair formation likely occurs on the breeding grounds (Bookhout 1995). Females have only one brood per season, although females that do not hatch their first clutch may renest (Stenzel 1982). Both males and females share the first stage of nest building, making crude scrapes in the vegetation. The hen finishes off the selected nest by herself, and continues to add to it throughout incubation and brooding (Stalheim 1974). The nest usually rests on the ground or just a few centimeters above it, and is typically covered with a concealing canopy of dead vegetation. Its walls are about 6-16 cm thick, made of fine vegetation woven into a cup 7-10 cm in diameter and 3-8 cm deep (Bookhout 1995, Robert and Laporte 1996). Yellow Rails may build more than one nest, using extra ones for brooding (Stenzel 1982).
The 7-10 eggs are laid a day apart. Incubation, carried out by the female alone, usually begins when laying is complete and continues for 17-18 days. Hatching is synchronous, and within a few hours the semiprecocial young can stand. Two days after hatching, the entire brood follows the hen away from the nest. The chicks have a small claw, or wing-claw, on each wing that they use to grip the vegetation as they roam around and when they climb back into the nest. They begin to feed themselves at about five days, are no longer brooded at three weeks, and fledge by 35 days (Stalheim 1974). Age at independence is unknown (Bookhout 1995).
Males may breed successively with two or more females, at least in captivity (Stalheim 1974). Unlike most other rallids, captive male Yellow Rails do not tend the young and stop associating with the female once incubation begins. However, Stenzel (1982), who worked in a natural setting, observed young in the company of both parents, as well as a male with chicks. He also observed a male with his mate at hatching time. The male Yellow Rail therefore could quite probably help taking care of the young--even if he is polygynous. Detailed studies of the mating system are lacking, and since non-monogamous mating is known to occur in the wild in only five of the world’s more than 130 rail species (del Hoyo et al., 1996), the Yellow Rail is sometimes presumed to form only monogamous pairs (Stenzel 1982, Bookhout 1995). Yet, other studies suggest that monogamy may not be the only mating system typical of this species: for example, both Stenzel (1982) and Robert and Laporte (1996) located nests of two females in the territory of one male.
Hatching success is likely very high; in Québec for example, all the eggs (9/9) in the nest found by Terrill (1943) hatched, and of the six nests found at l' Île aux Grues three had all the eggs hatch (9/9, 9/9, 9/9), two had 8 of 9 and 7 of 8 hatch and one had 7 of 9 hatch (Robert and Laporte 1996). Survival rates and nesting success should be similar to those found in other rails. Using birds of both sexes and all ages, Conway et al. (1994) found survival rates (from August to April) of 0.31 ± 0.26 for Soras and 0.55 ± 0.19 for Virginia Rails (Rallus limicola). They also found a nesting success rate of 0.53 for both species (which is a bit lower than for other rails).
When several pairs breed in the same marsh, activity areas of nesting birds overlap somewhat (Bookhout and Stenzel 1987). The males nonetheless patrol and seem to defend territories (Stalheim 1974, Bookhout 1995). Activity areas of mated males are often large compared to those of females. In Michigan, mated males occupied a mean area of about 8 ha (range: 5.8-10.5 ha), while females remained in a 1-2 ha area before incubation and a 0.5 ha area during incubation (Bookhout and Stenzel 1987). Densities of breeding males were one per 25 ha and one per 86 ha for Klamath Marsh National Wildlife Refuge and Seney National Wildlife Refuge, respectively (Bookhout 1995).
Yellow Rails usually arrive in the northern U.S. during the last week of April or the first week of May (Bookhout 1995). In southern Canada the first individuals are usually detected as early as 15 May (Robert and Laporte 1996, McGillivray and Semenchuk 1998). Water depth and temperature at breeding sites seem to affect establishment in spring (Stenzel 1982, Kaufman 1994). Very cold temperatures are avoided, and birds become lethargic and easy to capture (Stalheim 1974, Ripley 1977). Fall migration usually does not start until the second half of September or early October (Devitt 1939, Walkinshaw 1939, Manning 1952), continuing through October and early November. The latest date of fall occurrence in southern Québec is 26 October (Robert et al., 1995) and the earliest fall arrival in Louisiana is 6 October (Bookhout 1995).
Yellow Rails migrate at night, and some may migrate in groups: Pulich (1961) once recovered 13 individuals under a 500-m TV tower in Texas, and at least 28 flushed from a burning field in coastal North Carolina (Chapman 1969). They migrate in a broad front across the continent, as indicated by the distribution of published migration records (Cooke 1914, Bookhout 1995, AOU 1998). Even though they look like poor fliers, they cover impressive distances (Ripley 1977, Remsen and Parker 1990). Stalheim (1974) estimates that 2-3 weeks are required for the Yellow Rail to travel from the Gulf of Mexico to its breeding range.
In 15 years of banding Yellow Rails at Seney National Wildlife Refuge, Michigan, R. Urbanek observed that males lacked strong fidelity to breeding territories; each year the same territories were occupied by different males, and of 134 breeding males banded there, only two were recaptured, both the year after being banded (Bookhout 1995). Similar results were obtained on Ile aux Grues (Québec), which had nesting areas and non-nesting areas. Of 21 birds banded in the nesting areas from 1993-1995, only 2 (9.5%) were recaptured on the island during the nesting period the year after they were banded. This was despite the fact that all males calling on the island each year were banded (75 were banded over the years).
In a recent study, a few Yellow Rails moved along the St. Lawrence River corridor from their nesting area to Ile aux Grues in order to molt, seemingly because the island harbours the largest high-marshes (ca. 530 ha) along the St. Lawrence corridor and is apparently free of terrestrial predators (Robert and Laporte 1999). Although these movements may not have been indicative of a genuine molt migration, they suggest a molt migration similar in some ways to that of many waterfowl. Among rallids, Eurasian Coots (Fulica atra) and American Coots (F. americana) are the only species known to have developed true molt migrations (del Hoyo et al., 1996).
The most important food of Yellow Rails has traditionally been considered to be snails (Walkinshaw 1939, Stalheim 1974, Ripley 1977), but this has been based largely on anecdotal information. Yellow Rails definitely eat snails, but they also eat a variety of other invertebrates as well as seeds (Robert et al., 1997). For example, in Québec during summer, invertebrates and seeds had relative frequencies of 68% and 32%, respectively, with beetles (Coleoptera) representing almost two-thirds of the invertebrates taken. Spiders (Araneae) were second while other taxa (e.g. snails (Gastropoda) and flies (Diptera)) ranked much lower. Of the seeds identified, Cyperaceae and Juncaceae, particularly genera such as Carex, Juncus, and Eleocharis, were the most important food items. Winter, fall and spring food habits are probably similar to the summer diet, but the proportion of seeds could be higher (see Robert et al., 1997). In summary, the Yellow Rail is mostly an arthropod-feeder that complements its diet with seeds.
The Yellow Rail is probably a daytime feeder, like most other rails, foraging in areas of shallow water concealed by dense vegetation. It picks its food from ground, from the surface of, and sometimes from below (3-4 cm) the water surface. It drinks by dipping its bill in water while opening and closing it, then lifting it out horizontally (Stalheim 1974, Bookhout 1995).
The Yellow Rail’s “mouse-habits” are well-known by contemporary bird watchers and ornithologists. During daylight hours, it usually walks or runs, but almost never flies unless disturbed (for example if pursued by a dog)(Bookhout 1995, Robert 1997). It is particularly difficult to see upon approach, because, like other rails of its genus it usually remains stationary in the vegetation rather than fleeing as do other rails (Ripley 1977). It expertly slips through and hides in the dense marsh vegetation, aided by its buffy-and-black camouflage.
Its call is of particular interest, not only because it is often the only link between the bird and man, but also because it is quite peculiar. It is a rapid series of usually five monotonous and metallic ticks (or clicks) sounding like two pebbles tapped together: tick-tick, tick-tick-tick. In good atmospheric conditions, the clicking can be heard a kilometer away (Robert and Laporte 1996). Males click their “nuptial castanets” (Peabody 1922) much more often and regularly at night than during daytime.
Yellow Rail behaviour changes at night. Birds can be heard for hours, almost incessantly, often continuing until first light. They are much easier to flush or approach at night (Robert and Laporte 1996, Robert 1997). Many bird species living in dense vegetation are heard more regularly at night than by day, probably because their communication system is not dependent on vision, acoustic conditions are better, and the chances of attracting predators are reduced (Stalheim 1974). For example, three species that often nest in the same habitat as Yellow Rails-- Sedge Wren, Le Conte’s Sparrow, and Nelson’s Sharp-tailed Sparrow--also sing persistently at night, sometimes more than by day. This does not mean, as some have concluded, that the Yellow Rail is nocturnal. In many respects, it is much more active during the day than at night. For example, it does not feed at night, and its sexual and agonistic behaviours are much more frequent by day (Stalheim 1974). Moreover, it usually does not move about at night (unless disturbed), but calls from a stationary point (Stenzel 1982, Robert and Laporte 1996).
In Michigan (and probably in many other nesting localities across Canada and the U.S.), males usually cease calling in July (Stenzel 1982). The situation is similar in most localities where the species was recently found in Québec (Robert and Laporte 1996), except at Île aux Grues, where they usually stopped calling gradually from the first days of August until the last week of August. This difference is probably due to some individuals moving to Île aux Grues after nesting, apparently to molt. Although calling there ceases in late August, birds remain on the island for a few weeks afterwards and undergo a complete prebasic molt (Robert and Laporte 1996, Robert and Laporte 1999); as in other rallids, adult Yellow Rails lose all of their remiges and rectrices at once, as well as many body feathers, at the end of each summer before migrating south. They remain flightless for about two weeks (Stalheim 1974, Robert and Laporte 1996).
B. Eddleman (pers. comm.) suggests that Yellow Rails likely call very little or not at all on their wintering grounds. Very little is known about the species’ distribution and ecology in winter, and the fact that there has been no substantive survey and/or study of the Yellow Rail on the wintering grounds is probably due to this species remaining largely silent in winter. As part of the first such study, K. Mizell (pers. comm.) has found after two years of field work in Texas that the birds do not call, nor do they respond to playbacks.
The Yellow Rail is one of the most seldom seen nesting birds in the U.S. and Canada. However, during the nesting season, a calling male can be captured by slowly approaching it within about 15 m, then imitating the call by tapping two small stones persistently until it approaches, after which it can be captured with a hand net (Bookhout 1995, Robert and Laporte 1997). Males are usually easily manipulated and seem fairly resistant to handling. In one study, all 71 males that regurgitated after having tartar emetic injected down the esophagus showed no sign of illness when released and no significant differences were found in the weights of pre-treatment and post-treatment birds that were recaptured (Robert et al., 1997). However, females seem quite sensitive to handling during the nesting season (Stenzel 1982, M. Robert pers. obs.).
Stalheim (1974) maintained Yellow Rails in captivity, and some even reproduced. A major problem was inducing them to take prepared food; this had to be done gradually and the recipe had to be prepared with care. Probably the best way to ensure reproduction is to keep the birds in a natural setting that can provide natural live food and concealing vegetation (Stalheim 1974).
The dispersal capabilities of rallids in general are considered very good and this is probably also the case for Yellow Rails (Remsen and Parker 1990). Recent banding recoveries indicate that many individuals apparently move (sometimes many hundreds kilometers) along the St. Lawrence River corridor (Québec) from one site to another during their calling period (Robert and Laporte 1999). The ephemeral nature of marshes and wet grasslands habitats dictates that most rallids must be good dispersers. Most freshwater marshes proceed through various droughts, floods, and/or successional stages (Remsen and Parker 1990), which explains why Yellow Rails, like other rallids, may occur at unpredictable times and places. For example, in 1994, Yellow Rails were found in unusual numbers in the northern prairies, as in Saskatchewan and around North Dakota, while they were apparently absent from Churchill that year (Kaufman 1994). The population at the Seney National Wildlife Refuge also varied from 1 to 85 singing males from 1995 to 1998 (R. Urbanek, pers. comm.). In the Rainy River region of Ontario in 1995, which was a late, wet spring, an area 6 km southeast of the Big Marsh had numerous small meadows in which Yellow Rails could be heard; that same area in 1994, a dry year, had none singing (D. Elder, pers. comm.).
Yellow Rails are sometimes found in croplands, especially during migration. Maturerice fields seem to provide an appropriate “artificial” habitat for migrating (and probably wintering), and seem to be used extensively by Yellow Rails(Lowery 1974, Cardiff and Smalley 1989). This is not surprising because habitat selection may be influenced primarily by plant physiognomy and maximum water levels (Robert and Laporte, in prep.), and rice fields are very similar to sedge marshes in that they have dense, fairly low herbaceous vegetation where there is very little or almost no standing water but where the substrate usually remains saturated.
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