Use of saltwater and freshwater habitats by wintering redheads in southern Texas

Woodin, Marc C.

doi:10.1007/978-94-011-1128-7_26

Cited by 7 publications

(9 citation statements)

References 22 publications

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“…It is possible that the reduced levels of feeding by redheads in the upper Laguna Madre region are related to the availability of nearby freshwater ponds (Michot et al, 2005). To assist their salt glands with flushing of excess salt, redheads in the upper Laguna Madre obtained drinking water at coastal ponds (Adair, 1990;Moore, 1991;Woodin, 1994), while redheads in the lower Laguna Madre apparently obtained most of their drinking water from agricultural drains (used heavily by redheads) entering the lagoon from the mainland; little drinking by redheads on coastal ponds along the lower Laguna Madre was observed . Because fresh water was available to birds wintering in both the upper and lower basins of the Laguna Madre, however, the large overall difference in feeding levels between redheads wintering in the upper (26%) and lower (46%) Laguna Madre probably cannot be attributed to salt loading and the metabolic costs of osmoregulation.…”

Section: Discussionmentioning

confidence: 93%

“…Heavy use by redheads of coastal ponds along the entire length of the Laguna Madre is a widely reported phenomenon (Adair, 1990;Moore, 1991;Mitchell et al, 1992;Woodin, 1994;Adair et al, 1996;Skoruppa & Woodin, 2000;Michot et al, 2005), including the use of these ponds as sources of drinking water. Redheads begin arriving at coastal ponds at dawn, and exchange of birds between the Laguna Madre and coastal ponds occurs continuously until dusk, when the ponds largely are abandoned.…”

Section: Discussionmentioning

confidence: 96%

“…Redheads wintering in Texas use both freshwater and saltwater habitats, although redhead foraging essentially is limited to salt water (Adair, 1990;Mitchell et al, 1992;Woodin, 1994). Redheads in Louisiana also limit their feeding to saltwater habitats (Michot & Nault, 1993;Michot et al, 1994).…”

Section: Introductionmentioning

confidence: 98%

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Foraging behavior of redheads (Aythya americana) wintering in Texas and Louisiana

Woodin

Michot

2006

Hydrobiologia

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Redheads, Aythya americana, concentrate in large numbers annually in traditional wintering areas along the western and northern rim of the Gulf of Mexico. Two of these areas are the Laguna Madre of Texas and Chandeleur Sound of Louisiana. We collected data on 54,340 activities from 103 redhead flocks in Texas and 51,650 activities from 57 redhead flocks in Louisiana. Males and females fed similarly, differing neither in levels of feeding (percent of all birds in flock that were feeding) (p>0.90) nor in percentages of birds feeding by diving, tipping, dipping, or gleaning from the surface (p>0.10). The foraging level of redheads in the upper Laguna Madre region was relatively constant throughout two winters. Foraging of redheads in early winter in Louisiana was significantly greater than redhead foraging in the upper Laguna Madre, but by late winter, foraging by redheads in Louisiana had declined to the same level as that shown by redheads foraging in the upper Laguna Madre. The overall foraging level of redheads from Chandeleur Sound was greater (41%) than that of redheads in the upper Laguna Madre (26%), yet it was quite similar to the 46% foraging level reported for redheads from the lower Laguna Madre. Redheads in the upper Laguna Madre region of Texas fed more by diving than did those in the Chandeleur Sound and the lower Laguna Madre. Diving increased in frequency in late winter. Greater reliance by redheads on diving in January and February indicates that the birds altered their foraging to feed in deeper water, suggesting that the large concentrations of redheads staging at this time for spring migration may have displaced some birds to alternative foraging sites. Our results imply that the most likely period for food resources to become limiting for wintering redheads is when they are staging in late winter.

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Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 96%

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Foraging behavior of redheads (Aythya americana) wintering in Texas and Louisiana

Woodin

Michot

2006

Hydrobiologia

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“…Increased occurrence of preening and other comfort activities for redheads on freshwater ponds have been noted by Woodin (1994) and Mitchell et al (1992). The high degree of comfort movements and swimming behavior on the ponds could be displacement behavior in response to crowding caused by the high densities of birds and decreased spacing on the ponds (Adair, 1990).…”

Section: Discussionmentioning

confidence: 96%

“…Because of the frequently hyperhaline (>35 ppt) conditions in the Laguna Madre and adjacent Redfish Bay, redheads in southern Texas typically fly to adjacent fresh or slightly brackish (0-12 ppt) wetlands to drink (Moore, 1991;Woodin, 1994;Adair et al, 1996;Michot, 2000;Skoruppa & Woodin, 2000). Supplementary fresh water is not used by redheads wintering at Chandeleur Sound, where waters are hypohaline (20-30 ppt) because of the outflow of fresh water from the Mississippi River and other rivers into coastal waters (Michot, 2000).…”

Section: Introductionmentioning

confidence: 98%

Diurnal time-activity budgets of redheads (Aythya americana) wintering in seagrass beds and coastal ponds in Louisiana and Texas

et al. 2006

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Diurnal time-activity budgets were determined for wintering redheads (Aythya americana) from estuarine seagrass beds in Louisiana (Chandeleur Sound) and Texas (Laguna Madre) and from ponds adjacent to the Laguna Madre. Activities differed (p<0.0001) by location, month, and diurnal time period. Resting and feeding were the most frequent activities of redheads at the two estuarine sites, whereas drinking was almost nonexistent. Birds on ponds in Texas engaged most frequently in resting and drinking, but feeding was very infrequent. Redheads from the Louisiana estuarine site rested less than birds in Texas at either the Laguna Madre or freshwater ponds. Redheads in Louisiana fed more than birds in Texas; this was partially because of weather differences (colder temperatures in Louisiana), but the location effect was still significant even when we adjusted the model for weather effects. Redheads in Louisiana showed increased resting and decreased feeding as winter progressed, but redheads in Texas did not exhibit a seasonal pattern in either resting or feeding. In Louisiana, birds maintained a high level of feeding activity during the early morning throughout the winter, whereas afternoon feeding tapered off in mid-to late-winter. Texas birds showed a shift from morning feeding in early winter to afternoon feeding in late winter. Males and females at both Chandeleur Sound and Laguna Madre showed differences in their activities, but because the absolute difference seldom exceeded 2%, biological significance is questionable. Diurnal time-activity budgets of redheads on the wintering grounds are influenced by water salinities and the use of dietary fresh water, as well as by weather conditions, tides, and perhaps vegetation differences between sites. The opportunity to osmoregulate via dietary freshwater, vs. via nasal salt glands, may have a significant effect on behavioral allocations.

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Impacts of wind turbines on redheads in the Laguna Madre

2018

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Freshwater ponds adjacent to the Laguna Madre along the lower Texas coast provide an important and heavily used source of fresh water for the redhead (Aythya americana) throughout winter. A 267‐turbine wind farm was constructed within the core wintering area of the redhead on a private ranch along the western coast of the Laguna Madre, in 2010. Our objective was to investigate the effects of this wind farm on the habitat and potential displacement of redheads and their use of coastal ponds along the lower Texas coast. We conducted weekly aerial surveys to monitor coastal pond use by wintering redheads from mid‐October through mid‐March during pre‐construction (2000–2003) and post‐construction (2012–2014) of the wind farm. Pond availability and Palmer Drought Severity Index (PDSI) within the wind farm were significantly correlated during pre‐construction (n = 16, R2 = 0.53, P = 0.035) and post‐construction (n = 11, R2 = 0.64, P = 0.003). However, the number of ponds available at each PDSI level within the wind farm decreased during post‐construction (paired t = 3.2, n = 5, P = 0.033). The average number of redheads detected per survey on coastal ponds within the wind farm decreased by 77% from pre‐construction to post‐construction. Redhead abundance on ponds across the entire Laguna Madre increased by an average of 3.26 times between pre‐construction and post‐construction, partly due to increases in the continental redhead population. It appears that the wind farm has altered the use of coastal ponds by redheads during winter. Future wind farm placement along the lower Texas coast should consider coastal pond distribution and the dynamics of redhead use between coastal ponds and foraging areas in the Laguna Madre. © 2018 The Wildlife Society.

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Use of saltwater and freshwater habitats by wintering redheads in southern Texas

Cited by 7 publications

References 22 publications

Foraging behavior of redheads (Aythya americana) wintering in Texas and Louisiana

Foraging behavior of redheads (Aythya americana) wintering in Texas and Louisiana

Diurnal time-activity budgets of redheads (Aythya americana) wintering in seagrass beds and coastal ponds in Louisiana and Texas

Impacts of wind turbines on redheads in the Laguna Madre

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