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Number of reports of Anna's Hummingbird across Idaho during the nonbreeding season (October-February) by year from 1976 to 2020. Sources are records solicited by the Intermountain Bird Observatory (IBO; 2015 to 2019), the database of the Idaho Bird Records Committee (IBRC; 1976 to 2020), and www.eBird. org (1976 to 2020). Anna's Hummingbird illustration by Bryce W. Robinson.
Source publication
Increased urbanization and supplementary feeding are implicated in driving the expansion of the range of the Anna’s Hummingbird (Calypte anna). In many areas this range expansion has been well described, but the recent expansion of the northeastern limit of the nonbreeding distribution, in winter in Idaho, has not yet been summarized. Using data fr...
Contexts in source publication
Context 1
... first Anna's Hummingbird documented in Idaho was in Lewiston, Nez Perce County, 20 November-17 December 1976 (Rogers 1977). Over the next 27 years, reports of Anna's Hummingbirds ranged from zero to two individuals annually (mean 0.64; Figure 1). During the winters of 2004-2011, reports in the IBRC database increased noticeably (range 2-7 individuals annually; mean 3.4; Figure 1). ...
Context 2
... the next 27 years, reports of Anna's Hummingbirds ranged from zero to two individuals annually (mean 0.64; Figure 1). During the winters of 2004-2011, reports in the IBRC database increased noticeably (range 2-7 individuals annually; mean 3.4; Figure 1). Via eBird, birders reported 151 independent winter records from 1976-2020 (mean 3.4, range 0-29 annually; Figure 1). ...
Context 3
... the winters of 2004-2011, reports in the IBRC database increased noticeably (range 2-7 individuals annually; mean 3.4; Figure 1). Via eBird, birders reported 151 independent winter records from 1976-2020 (mean 3.4, range 0-29 annually; Figure 1). The majority of these records were near two towns at lower elevations, Boise (832 m) and Lewiston (227 m), and mostly from October to February ( Figure 2). ...
Context 4
... the winters from 2015 to 2020, homeowners reported 36-61 individuals annually, mostly in southwestern Idaho (Figures 1 and 2). Homeowners also reported Anna's Hummingbirds outside of the period of wintering (October-February), such as an adult male in Boise observed singing regularly at the same location for four consecutive springs (2016)(2017)(2018)(2019), and an adult female photographed in the same neighborhood on 12 June 2020. ...
Context 5
... the expansion of Anna's Hummingbird has been modeled comprehensively for the species' core range ( Greig et al. 2017, Battey 2019, these studies were based on data sources that do not represent the trend in Idaho. Our collation of records in freely accessible databases (i.e., eBird and IBRC) shows that this level of documentation adequately detected the trend of Anna's Hummingbird's occurrence increasing over time (Figure 1). However, our additional effort to solicit records from the community shows that these databases underestimated the number of individuals present in the area. ...
Context 6
... exploration of age and sex ratios on this and other frontiers of range expansion may be informative for predicting the pace, success, and outcomes of continued colonization into new regions of expansion as they appear (Rutz 2008). Through banding and color-marking birds, we also gained a better understanding of the overall numbers of Anna's Hummingbirds in Idaho (Figure 1). Given that in other states the species' range expansion began with incidental sightings of few individuals (Clark and Russell 2012), our comparison of homeowners' counts versus numbers captured for banding implies that there may be a broad gap between apparent and actual numbers of individuals in these cases. ...
Context 7
... first Anna's Hummingbird documented in Idaho was in Lewiston, Nez Perce County, 20 November-17 December 1976 (Rogers 1977). Over the next 27 years, reports of Anna's Hummingbirds ranged from zero to two individuals annually (mean 0.64; Figure 1). During the winters of 2004-2011, reports in the IBRC database increased noticeably (range 2-7 individuals annually; mean 3.4; Figure 1). ...
Context 8
... the next 27 years, reports of Anna's Hummingbirds ranged from zero to two individuals annually (mean 0.64; Figure 1). During the winters of 2004-2011, reports in the IBRC database increased noticeably (range 2-7 individuals annually; mean 3.4; Figure 1). Via eBird, birders reported 151 independent winter records from 1976-2020 (mean 3.4, range 0-29 annually; Figure 1). ...
Context 9
... the winters of 2004-2011, reports in the IBRC database increased noticeably (range 2-7 individuals annually; mean 3.4; Figure 1). Via eBird, birders reported 151 independent winter records from 1976-2020 (mean 3.4, range 0-29 annually; Figure 1). The majority of these records were near two towns at lower elevations, Boise (832 m) and Lewiston (227 m), and mostly from October to February ( Figure 2). ...
Context 10
... the winters from 2015 to 2020, homeowners reported 36-61 individuals annually, mostly in southwestern Idaho (Figures 1 and 2). Homeowners also reported Anna's Hummingbirds outside of the period of wintering (October-February), such as an adult male in Boise observed singing regularly at the same location for four consecutive springs (2016)(2017)(2018)(2019), and an adult female photographed in the same neighborhood on 12 June 2020. ...
Context 11
... the expansion of Anna's Hummingbird has been modeled comprehensively for the species' core range ( Greig et al. 2017, Battey 2019, these studies were based on data sources that do not represent the trend in Idaho. Our collation of records in freely accessible databases (i.e., eBird and IBRC) shows that this level of documentation adequately detected the trend of Anna's Hummingbird's occurrence increasing over time (Figure 1). However, our additional effort to solicit records from the community shows that these databases underestimated the number of individuals present in the area. ...
Context 12
... exploration of age and sex ratios on this and other frontiers of range expansion may be informative for predicting the pace, success, and outcomes of continued colonization into new regions of expansion as they appear (Rutz 2008). Through banding and color-marking birds, we also gained a better understanding of the overall numbers of Anna's Hummingbirds in Idaho (Figure 1). Given that in other states the species' range expansion began with incidental sightings of few individuals (Clark and Russell 2012), our comparison of homeowners' counts versus numbers captured for banding implies that there may be a broad gap between apparent and actual numbers of individuals in these cases. ...
Citations
... This first documented successful breeding of the Anna's Hummingbird in Idaho provides a marker on the chronology of the species' range expansion into the state. This chronology has thus far been well documented through the methods outlined by Pollock et al. (2021). Continued focus and documentation of the increase in numbers, as well as of further instances of breeding, will provide fine-scale details to the ongoing range expansion experienced by this species since the urbanization of the West accelerated in the middle of the 20th century. ...
Anthropogenic changes have altered the historical distributions of many North American taxa. As environments shift, ecological and evolutionary processes can combine in complex ways to either stimulate or inhibit range expansion. Here we examine the role of evolution in a rapid range expansion whose ecological context has been well-documented, Anna's Hummingbird (Calypte anna). Previous work suggests that the C. anna range expansion is the result of an ecological release facilitated by human-mediated environmental changes, where access to new food sources have allowed further filling of the abiotic niche. We examine the role of gene flow and adaptation during range expansion from their native California breeding range, north into Canada and east into New Mexico and Texas, USA. Using low coverage whole genome sequencing we found high genetic diversity, low divergence, and little evidence of selection on the northern and eastern expansion fronts. Additionally, there are no clear barriers to gene flow across the native and expanded range. The lack of selective signals between core and expanded ranges could reflect i) an absence of novel selection pressure in the expanded range (supporting the ecological release hypothesis), ii) swamping of adaptive variation due to high gene flow, or iii) limitations of genome scans for detecting small shifts in allele frequencies across many loci. Nevertheless, our results provide an example where strong selection is not apparent during a rapid, contemporary range shift.
