Assessing Climate Change Vulnerability of Breeding Birds in Arctic ...

thermokarst disturbances, drainage patterns,and subsequent habitat changes arecomplicated and understudied (Martin et al.2009). Efforts are now targeting researchtowards improving our understanding ofclimate change effects on some of theseaspects of surface hydrology.There was also insufficient informationto address questions about genetics andphenology for most species. Species withlow genetic variation are generally thoughtto be more vulnerable to climate change (seeYoung et al. 2010). However, there is awidely acknowledged paucity of studiesdocumenting genetic variation other than afew targeted efforts (see species accounts forcitations) and some general assessments at abroader taxonomic level (e.g., Baker andStrauch 1988). Long-term data sets and/orregion-wide data sets relevant to phenologydo exist for some waterfowl (e.g. Larned etal. 2012), shorebirds (R. Lanctot,unpublished data; J. Liebezeit, unpublisheddata,), and other bird groups in the ArcticLCC region. Some of these data are beingused to examine the relationship betweenremotely sensed variables (e.g., NDVI) andbird arrival and nest initiation (D. Ward etal. unpublished). For the majority of birds,however, long-term data are non-existent,inadequate for phenology assessments, oravailable but not currently applied toassessing such changes.Limitations of the CCVI toolClimate change vulnerability indices are oneapproach to understanding the effects ofclimate on species (e.g., Rowland et al.2011). As with all approaches, there arelimitations to the NatureServe CCVI tooland how it is applied. Most importantly, theCCVI tool does not examine statistical ormechanistic relationships between thespecies traits and their exposure to climatechange. Rather, the tool was designed tooffer a relatively coarse, quick, andconsistent look at the potential vulnerabilityof multiple species in a way that accountsfor numerous factors. It is structured toreadily add new information and revise theassessments as knowledge of the species andsystem increases and may be used toidentify need for more targeted researchefforts.There are also issues related to themanner in which we conducted ourassessment. The CCVI tool was developedto consider a wide range of both plant andanimals species in an area. Our narrow focuson birds tested its ability to parse out morenuanced differences in sensitivities andrelative vulnerabilities between closelyrelated species. As illustrated by themodifications suggested by expertparticipants and documented in the Methodssection, the generalized language onsensitivity factors from the CCVI guidancewas sometimes challenging to relate to birdsin the Arctic and, in a few cases, irrelevantaltogether. Although participants did notidentify any missing sensitivity factors priorto its application, many of themrecommended that the differential weightingof particular sensitivity factors onvulnerability outcomes be allowed. Forexample, some workshop participantsquestioned whether factors such asdisturbance effects and genetic influence onclimate change response should carry equalweight. Another challenge, regarding theeffects of climate-related changes indisturbance regimes, is that changes in sometypes of disturbance might benefit a specieswhile others might be detrimental, makingthe net effect difficult to determine andscore.Finally, many species we examinedrange widely across the world and areexposed to different climate stressors at theirwintering and staging areas. We exploredclimate change impacts for the shorebirdsubgroup across their flyways (Appendix C),28