diff --git a/Reports/usace_2023.Rmd b/Reports/usace_2023.Rmd index 9797360..2355b05 100644 --- a/Reports/usace_2023.Rmd +++ b/Reports/usace_2023.Rmd @@ -195,7 +195,7 @@ weather_report("precipitation", plot_year=params$report_year) #### Nesting effort - We estimated that a minimum of 34,227 wading bird nests were initiated at colonies within WCA 1, 2 and 3 and an additional 7,884 nests in ENP (Table \@ref(tab:nesting)). Wood Storks initiated nesting in WCA 3 (690 nests) as well as ENP (794) in 2023. And Roseate Spoonbills continued to nest in the WCAs and were present in at least 10 colonies. Large numbers of nesting Roseate Spoonbills were observed in Alley North (107 nests) and 6th Bridge (65 nests). + We estimated that a minimum of 25,775 wading bird nests were initiated at colonies within WCA 1, 2 and 3 and an additional 7,884 nests in ENP (Table \@ref(tab:nesting)). Wood Storks initiated nesting in WCA 3 (690 nests) at Jetport South, as well as several colonies in ENP (794) in 2023. Roseate Spoonbills continued to nest in the WCAs and were present in at least 10 colonies. Large numbers of nesting Roseate Spoonbills were observed in Alley North (107 nests) and 6th Bridge (65 nests). ```{r nesting} max_counts() %>% @@ -246,7 +246,7 @@ ggmap::ggmap(ggmap::get_map(location = location, ``` - We also continued long-term monitoring of small colonies, primarily small dark herons, in WCA 3. Note that because of low detection rates of small dark herons from the air, these species are not systematically counted in aerial surveys, and our total counts in the summary tables are derived from partial coverage obtained from ground survey transects and observations from the air when possible. The small dark heron counts should therefore be treated as bare minimums. The only indicator of trends of these species is through comparing the same ground surveys in selected transects over time as an index of abundance (Table \@ref(tab:ground)). Based on these surveys, there has been an overall trend towards fewer numbers of Tricolored Heron and Little Blue Heron nests in the study area since 2000. This decline has been accompanied by a large increase in numbers of Black-crowned Night Heron presence in the same colonies. Despite an overall decrease in Tricolored and Little Blue Heron trends for the period of record, there has been an uptick in Little Blue Heron presence starting in 2015. This upward trend continued in 2023 with the highest nesting effort (462 nesting pairs) in small tree islands in the last 22 years, 3.1 times the 10 year average. In contrast, Tricolored Heron nest numbers only increased slightly from last year, with 52 nesting pairs observed. Tricolored Heron nesting effort was 2.5 times the ten-year average. This pattern could be the result of a general reduction in nesting by Tricolored Herons throughout the Everglades, or it could indicate that these species are nesting elsewhere in the system such as in larger colonies or in coastal areas. For logistical reasons, Egretta herons are difficult to count in large colonies. However, large numbers of nesting Little Blue and Tricolored Herons have been observed in large mixed species colonies. Competing predictions about the declines are being addressed, such as a decline or shifts in composition of the prey base, displacement by Black-crowned Night Herons, or movement to coastal colonies. Black-crowned Night Herons are likely to be a predator on nestlings of Egretta herons; the night herons have been increasing as nesters rapidly during the past ten years and this upward trend continued in 2023 with 1.9% and 2.3% of the five- and ten-year averages during systematic ground surveys (1882 nests, Figure \@ref(fig:groundplot)). The sudden decrease in Little Blue and Tricolored herons correlates with the sharp increase of Black-crowned night heron presence on small tree islands. The slight increase in Tricolored Heron nesting effort and recovery of Little Blue Heron nesting effort could suggest that small herons are adjusting to Black-crowned Night Heron presence in small tree islands. + We also continued long-term monitoring of small colonies, primarily small dark herons, in WCA 3. Note that because of low detection rates of small dark herons from the air, these species are not systematically counted in aerial surveys, and our total counts in the summary tables are derived from partial coverage obtained from ground survey transects and observations from the air when possible. The small dark heron counts should therefore be treated as bare minimums. The only indicator of trends of these species is through comparing the same ground surveys in selected transects over time as an index of abundance (Table \@ref(tab:ground)). Based on these surveys, there has been an overall trend towards fewer numbers of Tricolored Heron and Little Blue Heron nests in the study area since 2000. This decline has been accompanied by a large increase in numbers of Black-crowned Night Heron presence in the same colonies. Despite an overall decrease in Tricolored and Little Blue Heron trends for the period of record, there has been an uptick in Little Blue Heron presence starting in 2015. This upward trend continued in 2023 with the highest nesting effort (462 nesting pairs) in small tree islands in the last 22 years, 3.1 times the 10 year average. In contrast, Tricolored Heron nest numbers only increased slightly from last year, with 52 nesting pairs observed. Tricolored Heron nesting effort was 2.5 times the ten-year average, but still far fewer nesting pairs than when surveys began. This pattern could be the result of a general reduction in nesting by Tricolored Herons throughout the Everglades, or it could indicate that these species are nesting elsewhere in the system such as in larger colonies or in coastal areas. For logistical reasons, Egretta herons are difficult to count in large colonies. However, large numbers of nesting Little Blue and Tricolored Herons have been observed in large mixed species colonies. Competing predictions about the declines are being addressed, such as a decline or shifts in composition of the prey base, displacement by Black-crowned Night Herons, or movement to coastal colonies. Black-crowned Night Herons are likely to be a predator on nestlings of Egretta herons; the night herons have been increasing as nesters rapidly during the past ten years and this upward trend continued in 2023 with 1.9% and 2.3% of the five- and ten-year averages during systematic ground surveys (1882 nests, Figure \@ref(fig:groundplot)). The sudden decrease in Little Blue and Tricolored herons correlates with the sharp increase of Black-crowned night heron presence on small tree islands. The slight increase in Tricolored Heron nesting effort and recovery of Little Blue Heron nesting effort could suggest that small herons are adjusting to Black-crowned Night Heron presence in small tree islands. ```{r ground} load_datafile("Counts/groundcounts.csv", path = get_default_data_path()) %>%