European starlings (Sturnus vulgaris) were using downtown Omaha, Nebraska, as a winter roosting s... more European starlings (Sturnus vulgaris) were using downtown Omaha, Nebraska, as a winter roosting site. We used radio telemetry and leg streamers to track birds in this roost. Between late December 2005 and March 2006, we radio tagged 57 starlings and located them 432 times. We attached leg bands and colored leg streamers to over 1,300 starlings captured at trapping sites within 7 km (4 mi) of the downtown roost. These techniques yielded data on previously unknown sites where starlings gathered to forage, stage, and roost. The maximum distance that a marked bird was observed from the downtown roost was 35 km (22 mi). An effective starling management plan was implemented based on the movement and activity data we collected.
ABSTRACT In the U.S., DRC-1339 baitings for blackbirds (Icteridae) are generally done under the p... more ABSTRACT In the U.S., DRC-1339 baitings for blackbirds (Icteridae) are generally done under the pesticide label, Compound DRC-1339 Concentrate – Staging Areas. DRC-1339 is a slow-acting avicide and gives the birds enough time to leave the baiting sites. Carcass searches and other forms of onsite counts are ineffective. Instead, linear models (LM) are used. The LM are based on esophageal analyses of several blackbird species collected while feeding at staging area bait sites. Biases and large variances can occur with this type of sampling. As an alternative to the LM, we developed a semi-mechanistic model (SM) that combined mechanistic modeling of environmental and biophysical processes with statistical modeling of DRC-1339 toxicities, avian physical and physiological traits, and foraging behavior. We used simulated baiting scenarios in Missouri and Louisiana to quantify and compare mortality between the LM and SM. The SM accounted for meteorological and regional effects on feeding rates, and we ran the SM scenarios for both mild and inclement weather conditions during January, a month when DRC-1339 baitings frequently occur. Mortality was calculated for males and females of three blackbird species. We used brown rice as the delivery substrate in a mix consisting of 11.34 kg untreated and 0.45 kg 2% DRC-1339 treated rice (1:25 dilution ratio). Compared to the LM, estimates by the SM ranged from 5% higher for male common grackles [Quiscalus quiscula L] to 59% lower for male brown-headed cowbirds [Molothrus ater Boddaert]. On average, the SM was 29% lower (x¯ = 8635, SE = 274.6) than the LM (x¯ = 12,131, SE = 1530.8, P < 0.001). Mortality estimates by the SM were 21% lower (x¯ = 7630, SE = 235.2, n = 12) under inclement than mild conditions (x¯ = 9641, SE = 276.3, P < 0.001). Latitudinal difference between the states did not affect mortality estimates produced by the SM (P > 0.65). Unlike the LM, the SM used avian physiological and behavioral responses to environmental and meteorological conditions based on individual characteristics of the modeled blackbird species. It represents a scientifically rigorous and broad-scale approach that can be applied at all staging area baitings regardless of region or time-of-year. The SM will produce much lower mortality estimates compared to the LM when brown-headed cowbirds are the major species using staging area sites.
European starlings (Sturnus vulgaris) were using downtown Omaha, Nebraska, as a winter roosting s... more European starlings (Sturnus vulgaris) were using downtown Omaha, Nebraska, as a winter roosting site. We used radio telemetry and leg streamers to track birds in this roost. Between late December 2005 and March 2006, we radio tagged 57 starlings and located them 432 times. We attached leg bands and colored leg streamers to over 1,300 starlings captured at trapping sites within 7 km (4 mi) of the downtown roost. These techniques yielded data on previously unknown sites where starlings gathered to forage, stage, and roost. The maximum distance that a marked bird was observed from the downtown roost was 35 km (22 mi). An effective starling management plan was implemented based on the movement and activity data we collected.
ABSTRACT In the U.S., DRC-1339 baitings for blackbirds (Icteridae) are generally done under the p... more ABSTRACT In the U.S., DRC-1339 baitings for blackbirds (Icteridae) are generally done under the pesticide label, Compound DRC-1339 Concentrate – Staging Areas. DRC-1339 is a slow-acting avicide and gives the birds enough time to leave the baiting sites. Carcass searches and other forms of onsite counts are ineffective. Instead, linear models (LM) are used. The LM are based on esophageal analyses of several blackbird species collected while feeding at staging area bait sites. Biases and large variances can occur with this type of sampling. As an alternative to the LM, we developed a semi-mechanistic model (SM) that combined mechanistic modeling of environmental and biophysical processes with statistical modeling of DRC-1339 toxicities, avian physical and physiological traits, and foraging behavior. We used simulated baiting scenarios in Missouri and Louisiana to quantify and compare mortality between the LM and SM. The SM accounted for meteorological and regional effects on feeding rates, and we ran the SM scenarios for both mild and inclement weather conditions during January, a month when DRC-1339 baitings frequently occur. Mortality was calculated for males and females of three blackbird species. We used brown rice as the delivery substrate in a mix consisting of 11.34 kg untreated and 0.45 kg 2% DRC-1339 treated rice (1:25 dilution ratio). Compared to the LM, estimates by the SM ranged from 5% higher for male common grackles [Quiscalus quiscula L] to 59% lower for male brown-headed cowbirds [Molothrus ater Boddaert]. On average, the SM was 29% lower (x¯ = 8635, SE = 274.6) than the LM (x¯ = 12,131, SE = 1530.8, P < 0.001). Mortality estimates by the SM were 21% lower (x¯ = 7630, SE = 235.2, n = 12) under inclement than mild conditions (x¯ = 9641, SE = 276.3, P < 0.001). Latitudinal difference between the states did not affect mortality estimates produced by the SM (P > 0.65). Unlike the LM, the SM used avian physiological and behavioral responses to environmental and meteorological conditions based on individual characteristics of the modeled blackbird species. It represents a scientifically rigorous and broad-scale approach that can be applied at all staging area baitings regardless of region or time-of-year. The SM will produce much lower mortality estimates compared to the LM when brown-headed cowbirds are the major species using staging area sites.
Uploads
Papers by George Linz