Golden-crowned Kinglet, a fairly common species of mature coniferous forests throughout Canada, the Pacific Northwest, montane regions of western U.S., and the Appalachians, was rather well represented in the 1992-2006 MAPS database with 1,423 adult individuals banded at 73 stations within 8 Bird Conservation Regions (BCRs); however, only 22 between-year recaptures of adults were recorded.  As shown in the spatial display of results, the largest numbers of adults were banded in the Northern Rockies (BCR 10) followed by the Sierra Nevada (BCR 15); these two BCRs accounted for over 60% of the total adults banded.  Only 88 adult individuals were banded (and no between-year recaptures of adults were recorded) away from western North America, all in the Atlantic Northern Forest (BCR14).

Temporal and spatial analyses of 1992-2006 program-wide MAPS data showed weighted mean population density indices for Golden-crowned Kinglet of 0.8 and 1.6 adults per station, respectively, from the selected models.  These density indices were very low, only about 29% and 44% as high, respectively, as the analogous mean density indices for all species on the website.  Among small insectivorous species, only Hutton’s Vireo, Blue-gray Gnatcatcher, Northern Parula, and Pine Warbler were captured with similar or lower adult densities, which, at least partially for all those species, likely reflect foraging beats that are relatively high in the canopy of tall trees.  Annual variability in population density (22.0%) was similar to the analogous mean variability for all species on the website, but spatial variability in population density (29.5%) was relatively low, only about 75% as high as the analogous mean variability for all species.

The weighted geometric mean of the model-averaged annual lambda estimates (0.888, which was not significantly different from 1.0) suggested a non-significantly decreasing population for Golden-crowned Kinglet, while the weighted geometric mean of the model-averaged BCR-specific lambda estimates (1.009, which also was not significantly different from 1.0) suggested a stable population.  This latter MAPS estimate was similar to the estimate from the 1992-2006 program-wide North American Breeding Bird Survey (BBS; a lambda of 1.007, which was not significantly different from 1.0) that suggested a stable or non-significantly increasing population for Golden-crowned Kinglet.  Annual variability in lambda for Golden-crowned Kinglet (35.8%) was high, about 55% higher than the analogous mean variability for all species included on the website.  In contrast, spatial variability in lambda (2.8%) was low, only about 50% as high as the analogous mean variability for all species.

Temporal and spatial analyses produced estimates for adult apparent survival for Golden-crowned Kinglet (0.134 and 0.107, respectively) that were the lowest of all 158 species included on the website, and were considerably lower than expected, even though Golden-crowned Kinglet had the lowest body mass of all 158 species on the website.  The species with the next lowest adult apparent survival estimates (Pine, Nashville, and Arctic warblers) had temporal and spatial estimates of adult apparent survival that were about 2.5 and nearly 3 times higher, respectively, than those for Golden-crowned Kinglet.  We suggest that these very low adult apparent survival estimates for Golden-crowned Kinglet reflect high emigration rates that result from low breeding site fidelity (and also account for the paucity of between-year recaptures), as well as possibly low true survival rates.  Both annual and spatial variabilities in adult apparent survival for Golden-crowned Kinglet (64.0% and 89.4%, respectively) were extremely high, the highest of all species on the website, and about 2.7 and 5.7 times higher, respectively, than the analogous mean variabilities for all species.  The very high variabilities in adult apparent survival likely reflect high variabilities in both emigration rates and true survival rates.  Golden-crowned Kinglet, at least in the West, is an irruptive migrant with large numbers of birds moving to the lowlands and to areas south of their breeding latitudes during some autumns, and many fewer in other autumns.  It seems likely that years with low breeding site fidelity and high adult emigration rates may follow years of autumn and winter eruptions (that also may be characterized by low true survival), and that the irruptive nature of this species is a cause of its very high annual variability of adult apparent survival.  In addition, it is likely that irruptive years are not synchronized or even consistent in overall extent across all of North America, or even throughout the West, thereby accounting for the species’ very high spatial variability in adult apparent survival as well.

Temporal and spatial analyses produced estimates for the productivity index for Golden-crowned Kinglet (1.151 and 1.105, respectively, from the selected models) that were the fourth highest of all species on the website, and reflected the high productivity indices characteristic of small species with very low body masses and low adult apparent survival rates.  Annual variability in productivity for Golden-crowned Kinglet (36.7%) was somewhat low, about 15% lower than the analogous mean variability for all species, while spatial variability in productivity (48.9%) was quite similar to the analogous mean variability for all species (47.5%).  Thus, productivity for Golden-crowned Kinglet did not show the very high annual and spatial variabilities shown by adult apparent survival.

Continent-wide temporal analyses among Golden-crowned Kinglet vital rates showed that lambda was rather strongly but non-significantly positively correlated with post-breeding effects (likely primarily reflecting annual variation in first-year survival of young), moderately and non- significantly positively correlated with productivity, and effectively not correlated at all with adult apparent survival.  These results suggest that annual variation in lambda was primarily driven by annual variation in post-breeding effects and secondarily by annual variation in productivity.  Post-breeding effects were strongly and significantly negatively correlated with adult apparent survival, and rather strongly but non-significantly negatively correlated with productivity, suggesting that possible competitive interactions between adult and young birds and among young birds may have influenced the annual variability in first-year survival of young that appeared to be the strongest driver of annual variations in lambda.  As perhaps expected from these latter two correlations, adult apparent survival was moderately but non-significantly positively correlated with productivity.

Continent-wide temporal analyses also showed that lambda was rather weakly and non-significantly positively correlated with the index of adult population density, suggesting that density dependence did not play a role in the population dynamics of Golden-crowned Kinglet.  Interestingly, however, adult apparent survival was very strongly and highly significantly negatively correlated with population density and productivity was moderately but non-significantly negatively correlated with population density, while post-breeding effects were rather weakly and non-significantly positively correlated with population density.  These results suggest that both adult apparent survival and productivity, but not post-breeding effects, were affected by density-dependence, very strongly so for adult apparent survival.  Thus, it appeared that the vital rate whose annual variation was the strongest driver of annual variation in lambda (post-breeding effects) was not the vital rate through which density dependence was primarily effected.

Because the only MAPS data not from the West were those from the Northern Atlantic Forest (BCR 14, for which no between-year recaptures of adults were recorded) and only 3 of the 88 adult individuals were banded during the initial 6 years of the 15-year study period), we repeated the temporal analysis for Golden-crowned Kinglet using a dataset that excluded data from BCR 14.  These latter analyses produced three substantially different results from those that were based on the entire dataset and were reported above: (1) lambda was strongly and significantly positively correlated with adult apparent survival, suggesting that annual variation in adult apparent survival was the most important driver of annual variation in lambda in the West; (2) post-breeding effects were only very weakly and non-significantly negatively correlated with adult apparent survival, suggesting little potential competition between young and adult birds in the West; and (3) lambda was very strongly and highly significantly negatively correlated with the index of adult population density, suggesting that a high degree of density dependence characterized Golden-crowned Kinglet populations in the West.

Spatial analyses among Golden-crowned Kinglet vital rates showed that lambda was not positively correlated with any of the three other vital rates, thereby suggesting that the drivers of Golden-crowned Kinglet population change differed dramatically across the continent.  The only two similarities between temporal and spatial correlations among vital rates were that adult apparent survival was moderately but not significantly positively correlated with productivity, and that post-breeding effects were strongly (and spatially significantly) negatively correlated with productivity.

Summary of research and management hypotheses – MAPS results from western North America suggest that fluctuations in Golden-crowned Kinglet populations likely result from major declines in some important resource (probably food), which trigger density-dependent irruptive autumn movements to the lowlands and to areas south of their breeding latitudes, and which, in turn, lower the survival rates of adult and, especially, young birds during the non-breeding season, and subsequently decrease breeding site fidelity and increase emigration of adults the following breeding season.  If these irruptive movements are frequent enough, or severe enough, they can drive population declines in this species.  The positive temporal correlations between adult apparent survival and productivity suggest that the declines in resources that trigger irruptive autumn movements may begin during the summer, so that productivity during the breeding season, as well as adult apparent survival the following non-breeding season, will be low.  Therefore, we suggest that research and management efforts to reverse declines of Golden-crowned Kinglets and maintain more stable or increasing populations should focus on identifying habitat characteristics that promote higher and more stable food resources, so as to decrease the frequency and severity of the conditions driving the irruptive movements of this species.  In addition, research and management should aim to identify and enhance habitat conditions on the non-breeding ranges that promote adequate food resources for the species when irruptive movements do occur.  Because the sources and end points of the irruptive movements of Golden-crowned Kinglets are very poorly known, considerably more information on migratory connectivity will be needed to ensure effective conservation for this species.  Finally, because the factors that drive the declines in food resources (which, in turn, trigger the irruptive movements) are likely to be strongly affected by weather condition, and because those weather conditions are likely to be greatly affected by climate change, we suggest that all of the research and management efforts outlined above must include detailed considerations of weather and climate change.

Please cite this narrative as:  DeSante, D. F., D. R. Kaschube, and J. F. Saracco.  2015.  Vital Rates of North American Landbirds.  www.VitalRatesOfNorthAmericanLandbirds.org: The Institute for Bird Populations.