DOI: 10.5061/dryad.n109f8t
title: Data from: Using citizen-science observations to understand long-term trends in common and Pacific loon populations in urbanized Southcentral Alaska

description: For over 30 years, the Alaska Loon Watch (1985−1999) and the Alaska Loon
 and Grebe Watch (2000−2015) engaged citizen scientist participants to
 record over 10,000 observations of common Gavia immer and Pacific loons
 Gavia pacifia at 346 lakes in five sub-regions of Southcentral Alaska. We
 used generalized linear mixed models to estimate long-term trends in adult
 loon counts and chick survival and examined environmental variables
 associated with loon abundance. Adult common loon counts increased in all
 five sub-regions by 0.6-3.6% per year, while Pacific loons decreased 3% in
 the Anchorage sub-region, but otherwise had trends not distinguishable
 from zero. Lake area was positively associated with common loon abundance
 and negatively associated with Pacific loon abundance. We also noted an
 inverse relationship between common loon and Pacific loon presence,
 consistent with the premise of interspecific competition. We did not find
 strong relationships between loon presence and predictor variables
 indicative of human disturbance or lakeshore development. Estimates of
 chick survival over time also revealed no clear pattern, although common
 loon chicks showed a decline in survival over the study period in one
 sub-region. Citizen science programs provide agencies with a
 cost-effective tool to collect data over large spatial and temporal
 extents, which may not be feasible otherwise. However, there are
 ramifications of common data deficiencies associated with casual or
 unstructured observations, which can violate the assumptions required for
 rigorous statistical analysis. A carefully pre-defined sampling protocol
 avoids sampling bias, eliminates stringent assumptions, and ensures higher
 information content of citizen-science data.
description: Table
 A1Citizen scientists
 collected observational data of common loon Gavia immer chick survival
 across five sub-regions of Southcentral Alaska; Anchorage, Joint Base
 Elmendorf-Richardson (JBER), Kenai Peninsula (Kenai), Matanuska-Susitna
 Valley (Mat-Su) and Outlying, 1985-2015. Data is summarized by sub-region,
 location or town within the sub-region, name of lake observed, year of
 observation, number of nesting pairs, number of chicks hatched per
 breeding pair and number of chicks that survived past the defined survival
 threshold (16 September for common loon, 26 August for Pacific loon). A
 metadata (data dictionary) file is associated with the data
 file.Table_A1.xlsxTable A2Citizen scientists collected data on anthropogenic and natural disturbances for lakes observed in the five sub-regions of Southcentral Alaska; Anchorage, Joint Base Elmendorf-Richardson (JBER), Kenai Peninsula (Kenai), Matanuska-Susitna Valley (Mat-Su) and Outlying, 1985-2015. Anthropogenic disturbances include: swimming, fishing, non-motor craft, motor boats, jet skis, float planes and dogs. Natural disturbances include: eagles, mammals and flooding. Disturbance is summarized by frequency of occurrence; daily, weekly, monthly, occasionally or never occurred. A metadata (data dictionary) file is included in this data file.Table_A2.xlsxTable A3Presence or absence of common loon Gavia immer and Pacific loon Gavia pacifica on lakes observed by citizen scientists in five sub-regions of Southcentral Alaska; Anchorage, Joint Base Elmendorf-Richardson (JBER), Kenai Peninsula (Kenai), Matanuska-Susitna Valley (Mat-Su) and Outlying, 1985-2015. Adults and chicks are ranked as (1) if present or (0) is absent from an observed lake. A metadata (data dictionary) file is associated with this data file.Table_A3.xlsxTable A4Number of structures located within a 150m buffer of lakes observed by citizen scientists in five sub-regions of Southcentral Alaska; Anchorage, Joint Base Elmendorf-Richardson (JBER), Kenai Peninsula (Kenai), Matanuska-Susitna Valley (Mat-Su) and Outlying, 1985-2015. Only lakes with a least 3 observations over a 5 year period and only years where Google Earth imagery was available were included in the analysis. A metadata (data dictionary) file is associated with this data file.Table_A4.xlsx