scholarly journals Territorial Behavior in Belted Kingfishers, Ceryle alcyon, During Fall Migration

2005 ◽  
Vol 119 (2) ◽  
pp. 293
Author(s):  
Michael J. Hamas
Keyword(s):  
Lake Huron ◽  
Territorial Behavior ◽  
Wintering Grounds ◽  
Ceryle Alcyon

The Belted Kingfisher (Ceryle alcyon) exhibits territorial behavior during breeding and on the wintering grounds. However, behavior during migration is poorly documented. Here, I report on kingfishers exhibiting territorial behavior during fall migration along the shoreline of northern Lake Huron, Michigan.

scholarly journals Toxins and Other Bioactive Metabolites in Deep Chlorophyll Layers Containing the Cyanobacteria Planktothrix cf. isothrix in Two Georgian Bay Embayments, Lake Huron

Toxins ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 445
Author(s):  
Arthur Zastepa ◽  
Todd R. Miller ◽  
L. Cynthia Watson ◽  
Hedy Kling ◽  
Susan B. Watson
Keyword(s):  
Thermal Stratification ◽  
Chemical Defence ◽  
Euphotic Zone ◽  
Lake Huron ◽  
Metabolic Inhibitors ◽  
Bioactive Metabolites ◽  
Total Biomass ◽  
Key Factors ◽  
Georgian Bay ◽  
And Function

The understanding of deep chlorophyll layers (DCLs) in the Great Lakes—largely reported as a mix of picoplankton and mixotrophic nanoflagellates—is predominantly based on studies of deep (>30 m), offshore locations. Here, we document and characterize nearshore DCLs from two meso-oligotrophic embayments, Twelve Mile Bay (TMB) and South Bay (SB), along eastern Georgian Bay, Lake Huron (Ontario, Canada) in 2014, 2015, and 2018. Both embayments showed the annual formation of DCLs, present as dense, thin, metalimnetic plates dominated by the large, potentially toxic, and bloom-forming cyanobacteria Planktothrix cf. isothrix. The contribution of P. cf. isothrix to the deep-living total biomass (TB) increased as thermal stratification progressed over the ice-free season, reaching 40% in TMB (0.6 mg/L at 9.5 m) and 65% in South Bay (3.5 mg/L at 7.5 m) in 2015. The euphotic zone in each embayment extended down past the mixed layer, into the nutrient-enriched hypoxic hypolimnia, consistent with other studies of similar systems with DCLs. The co-occurrence of the metal-oxidizing bacteria Leptothrix spp. and bactivorous flagellates within the metalimnetic DCLs suggests that the microbial loop plays an important role in recycling nutrients within these layers, particularly phosphate (PO4) and iron (Fe). Samples taken through the water column in both embayments showed measurable concentrations of the cyanobacterial toxins microcystins (max. 0.4 µg/L) and the other bioactive metabolites anabaenopeptins (max. ~7 µg/L) and cyanopeptolins (max. 1 ng/L), along with the corresponding genes (max. in 2018). These oligopeptides are known to act as metabolic inhibitors (e.g., in chemical defence against grazers, parasites) and allow a competitive advantage. In TMB, the 2018 peaks in these oligopeptides and genes coincided with the P. cf. isothrix DCLs, suggesting this species as the main source. Our data indicate that intersecting physicochemical gradients of light and nutrient-enriched hypoxic hypolimnia are key factors in supporting DCLs in TMB and SB. Microbial activity and allelopathy may also influence DCL community structure and function, and require further investigation, particularly related to the dominance of potentially toxigenic species such as P. cf. isothrix.

scholarly journals Diet of the Bobolink (Dolichonyx oryzivorus) in rice fields on its wintering grounds in Argentina

2019 ◽  
Vol 27 (1) ◽  
pp. 10-16
Author(s):  
Rodrigo E. Lorenzón ◽  
Carolina E. Antoniazzi ◽  
Franco N. Fabre ◽  
Virginia M. Quiroga ◽  
Silvia A. Regner ◽  
...  
Keyword(s):  
Stomach Contents ◽  
Rice Fields ◽  
Cultivated Plants ◽  
Relative Importance ◽  
Santa Fe ◽  
Wintering Grounds ◽  
Dolichonyx Oryzivorus ◽  
Winter Diet ◽  
Number Of Seeds ◽  
Plant Components

AbstractWinter diet of Bobolinks (Dolichonyx oryzivorus), a bird considered a pest of rice fields, is known to consist primarily of seeds. However, it is not yet possible to establish the extent to which non-rice plants and animal components contribute to its diet. To contribute to these issues, we studied the diet of the Bobolink found in rice fields on its wintering grounds in Santa Fe, Argentina, to provide information on (i) the composition of the diet and (ii) the relative importance of plant and animal components in the diet and of the different prey categories. We captured Bobolinks with mist nets and obtained samples of stomach contents by warm water and emetic-based regurgitation to determine the composition of the diet (n = 46 samples) and the importance of the different prey (n = 25 samples), mainly during March, just prior to northbound migration. We confirmed that the Bobolink’s diet in this region during this period is predominantly herbivorous (97%) and rice-based (55%), although it also consumes a large number of seeds of non-cultivated plants that represented 42% of the diet. Invertebrates, although of less importance than plant components (3%), had been consumed by 97% of captured individuais. Our results document the importance of non-cultivated plants and animal prey in the diet of Bobolinks in addition to rice.

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