4 Potential actions in response to climate change: Skuas (Stercorariidae)
In this section we list and assess possible local conservation actions that could be carried out in response to identified climate change impacts on skuas . This section is not grouped by species, but by identified impacts. If an impact or action is specific to one or a few species, this information is included in the action summary or in the footnotes.
4.1 Impact: Increase in avian predation
Summary:There are a number of available local actions to prevent or mitigate avian predation, some of which have been trialled extensively in seabirds with positive results. Other actions are poorly understood, but could be considered after more investigation. If predation is severe, and is likely to increase due to climate change or species range shifts, then translocation could be considered.| Intervention | Evidence of effectiveness | R | S | T |
|---|---|---|---|---|
| Artificial shelters to make nests less visible to aerial predators | This is a hypothetical action. There are no published studies assessing this action’s effectiveness | NA | NA | NA |
| Manage/eradicate avian predators | Has been trialled with some success on several seabird groups, though has never been trialled on skuas. Often carried out as part of a suite of conservation actions, making it difficult to assess how effective management is. | 2 | 3 | 3 |
| Physically protect nests with barriers or enclosures | Has been trialled on many seabird groups, often with notable success. Currently no reports on its effectiveness for skuas. A relatively easy, inexpensive method, but is dependent on being able to access nest-sites and effectively protect them. Since some skua species nest in very low densities across large areas of tundra, the practicality of this action may be questionable. | 2 | 4 | 4 |
| Reduce predation by translocating predators | Few trials on seabirds, and none on skuas. Existing evidence suggests this action can be beneficial and reduce egg/chick predation, and could be a viable action if other forms of predator management are not viable | 1 | 4 | 3 |
| Repel predators with acoustic, chemical or visual deterrents | This is a hypothetical action. There are no published studies assessing this action’s effectiveness | NA | NA | NA |
| Use supplementary feeding to reduce predation | Very few trials on seabirds, and none on skuas. Likely to be very labour intensive and difficult given the remote and inaccessible breeding colonies of many skuas. More work is needed to examine action’s effectiveness on seabirds. | 1 | 4 | 3 |
Green = Likely to be beneficial. Red = Unlikely to be beneficial, may have negative impact. Orange = contradicting or uncertain evidence. Grey = Limited evidence.
R = relevance rating. S = strength rating. T = transparency rating. All ratings on a scale of 1 to 5, where 5 is the highest.
Detail:
Manage/eradicate avian predators
Relevance (R): 0 studies in the evidence base focus on skuas, 14 on other seabirds and 2 on other birds. Strength (S): The evidence base was comprised of 16 studies. Of these 15 were considered to have a good sample size, and 5 had a clear metric for effectiveness. Transparency (T): 16 studies included were published and peer-reviewed, of which 1 were literature reviews or meta-analyses, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 9 had a published methodology, and 11 justified their rationale.
Physically protect nests with barriers or enclosures
Relevance (R): 0 studies in the evidence base focus on skuas, 12 on other seabirds and 6 on other birds. Strength (S): The evidence base was comprised of 18 studies. Of these 16 were considered to have a good sample size, and 12 had a clear metric for effectiveness. Transparency (T): 17 studies included were published and peer-reviewed, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 11 had a published methodology, and 12 justified their rationale.
Reduce predation by translocating predators
Relevance (R): 0 studies in the evidence base focus on skuas, 2 on other seabirds and 2 on other birds. Strength (S): The evidence base was comprised of 4 studies. Of these 4 were considered to have a good sample size, and 3 had a clear metric for effectiveness. Transparency (T): 4 studies included were published and peer-reviewed, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 2 had a published methodology, and 3 justified their rationale.
Use supplementary feeding to reduce predation
Relevance (R): 0 studies in the evidence base focus on skuas, 1 on other seabirds and 3 on other birds. Strength (S): The evidence base was comprised of 4 studies. Of these 4 were considered to have a good sample size, and 4 had a clear metric for effectiveness. Transparency (T): 4 studies included were published and peer-reviewed, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 1 had a published methodology, and 4 justified their rationale.
4.2 Impact: Increase in competition
Summary:Local actions to prevent or mitigate the effects of competition are not well understood, and their effectiveness is unclear. In many contexts they are likely to be difficult or impossible to carry out on large populations. Supporting populations more generally (increasing adult survival, limiting chick mortality) may be a more appropriate strategy.| Intervention | Evidence of effectiveness | R | S | T |
|---|---|---|---|---|
| Protect nest sites from competitors | Only trialled on one population of petrel (with limited success), all other examples focus on non-seabird species (many of which were successful). More work is needed to examine action’s effectiveness on seabirds. | 1 | 3 | 2 |
| Reduce competition by removing competitor species | Trialled extensively on terns, but limited trials for other seabird groups, and none for skuas. Success is mixed, some trials have found benefits, but many have reported no effect or even negative consequences of this action. | 2 | 3 | 3 |
| Use supplementary feeding to reduce competition | This is a hypothetical action. There are no reported studies assessing this action’s effectiveness | NA | NA | NA |
Green = Likely to be beneficial. Red = Unlikely to be beneficial, may have negative impact. Orange = contradicting or uncertain evidence. Grey = Limited evidence.
R = relevance rating. S = strength rating. T = transparency rating. All ratings on a scale of 1 to 5, where 5 is the highest.
Detail:
Protect nest sites from competitors
Relevance (R): 0 studies in the evidence base focus on skuas, 2 on other seabirds and 5 on other birds. Strength (S): The evidence base was comprised of 7 studies. Of these 5 were considered to have a good sample size, and 2 had a clear metric for effectiveness. Transparency (T): 6 studies included were published and peer-reviewed, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 3 had a published methodology, and 4 justified their rationale.
Reduce competition by removing competitor species
Relevance (R): 0 studies in the evidence base focus on skuas, 12 on other seabirds and 0 on other birds. Strength (S): The evidence base was comprised of 12 studies. Of these 10 were considered to have a good sample size, and 5 had a clear metric for effectiveness. Transparency (T): 12 studies included were published and peer-reviewed, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 8 had a published methodology, and 7 justified their rationale.
4.3 Impact: Increased thermal stress
Summary:There are currently no well-researched methods to directly assist seabirds with thermal stress, and more information is needed on how thermal stress can impact seabirds and how local conservation action can mitigate these impacts. If thermal stress becomes so common or extreme that it threatens the viability of a population, then several actions are available to encourage translocation of populations to safer areas.| Intervention | Evidence of effectiveness | R | S | T |
|---|---|---|---|---|
| Make new colonies more attractive to encourage birds to translocate | Has been tried extensively on many different seabird groups with frequent, though not universal, success. However, currently there are no reports on this action’s effectiveness for skuas. | 2 | 4 | 3 |
| Provide additional resources to help seabirds thermoregulate (e.g. artificial pools) | This is a hypothetical action. There are no published studies assessing this action’s effectiveness | NA | NA | NA |
| Provide additional shelter or protection from extreme weather (heatwaves) | Very limited number of trials in seabirds, some limited benefits found for providing additional shelter from the sun for cormorants. More work is needed to examine action’s effectiveness on seabirds. | 2 | 3 | 3 |
| Translocate the population to a more suitable breeding area | Known to be beneficial in some seabird groups, but no recorded trials in skuas. Skuas tend to have extremely high territoriality and site-fidelity so translocation of adults is likely to be extremely difficult, if not impossible. Whether translocation is plausible, or beneficial, to skuas is currently unknown and further research is needed. | 2 | 4 | 4 |
Green = Likely to be beneficial. Red = Unlikely to be beneficial, may have negative impact. Orange = contradicting or uncertain evidence. Grey = Limited evidence.
R = relevance rating. S = strength rating. T = transparency rating. All ratings on a scale of 1 to 5, where 5 is the highest.
Detail:
Make new colonies more attractive to encourage birds to translocate
Relevance (R): 0 studies in the evidence base focus on skuas, 38 on other seabirds and 6 on other birds. Strength (S): The evidence base was comprised of 44 studies. Of these 31 were considered to have a good sample size, and 18 had a clear metric for effectiveness. Transparency (T): 44 studies included were published and peer-reviewed, of which 1 were literature reviews or meta-analyses, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 30 had a published methodology, and 22 justified their rationale.
Provide additional shelter or protection from extreme weather (heatwaves)
Relevance (R): 0 studies in the evidence base focus on skuas, 1 on other seabirds and 0 on other birds. Strength (S): The evidence base was comprised of 1 study. Of these 1 was considered to have a good sample size, and 1 had a clear metric for effectiveness. Transparency (T): 1 study included were published and peer-reviewed, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 0 had a published methodology, and 1 justified their rationale.
Translocate the population to a more suitable breeding area
Relevance (R): 0 studies in the evidence base focus on skuas, 15 on other seabirds and 0 on other birds. Strength (S): The evidence base was comprised of 15 studies. Of these 13 were considered to have a good sample size, and 9 had a clear metric for effectiveness. Transparency (T): 14 studies included were published and peer-reviewed, of which 1 were literature reviews or meta-analyses, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 11 had a published methodology, and 9 justified their rationale.
4.4 Impact: Reduced prey availability during breeding season
Summary:Several local actions may assist breeding populations on a small scale, but direct intervention on a large scale is likely to be extremely difficult. General conservation actions to protect fish stocks and local marine areas may be the most effective method. If a population is likely to suffer major losses, even with conservation help, then translocations could be considered| Intervention | Evidence of effectiveness | R | S | T |
|---|---|---|---|---|
| Artificially incubate or hand-rear chicks to support population | Known to be effective for some seabirds, though labour intensive and usually only appropriate for small populations. To our knowledge, there are no examples of skuas being hand-reared successfully. | 2 | 2 | 1 |
| Make new colonies more attractive to encourage birds to translocate | Has been tried extensively on many different seabird groups with frequent, though not universal, success. However, currently there are no reports on this action’s effectiveness for skuas. | 2 | 4 | 3 |
| Provide supplementary food during the breeding season | Trialled on several seabird species, with some, though not universal, success. Trialled on only one population of skuas, which found little benefit. Typically very labour intensive and difficult given the remote and inaccessible breeding colonies of many skuas. Probably only plausible for small populations. | 3 | 4 | 3 |
| Translocate the population to a more suitable breeding area | Known to be beneficial in some seabird groups, but no recorded trials in skuas. Skuas tend to have extremely high territoriality and site-fidelity so translocation of adults is likely to be extremely difficult, if not impossible. Whether translocation is plausible, or beneficial, to skuas is currently unknown and further research is needed. | 2 | 4 | 4 |
Green = Likely to be beneficial. Red = Unlikely to be beneficial, may have negative impact. Orange = contradicting or uncertain evidence. Grey = Limited evidence.
R = relevance rating. S = strength rating. T = transparency rating. All ratings on a scale of 1 to 5, where 5 is the highest.
Detail:
Artificially incubate or hand-rear chicks to support population
Relevance (R): 0 studies in the evidence base focus on skuas, 40 on other seabirds and 0 on other birds. Strength (S): The evidence base was comprised of 40 studies. Of these 9 were considered to have a good sample size, and 19 had a clear metric for effectiveness. Transparency (T): 26 studies included were published and peer-reviewed, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 17 had a published methodology, and 4 justified their rationale.
Make new colonies more attractive to encourage birds to translocate
Relevance (R): 0 studies in the evidence base focus on skuas, 38 on other seabirds and 6 on other birds. Strength (S): The evidence base was comprised of 44 studies. Of these 31 were considered to have a good sample size, and 18 had a clear metric for effectiveness. Transparency (T): 44 studies included were published and peer-reviewed, of which 1 were literature reviews or meta-analyses, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 30 had a published methodology, and 22 justified their rationale.
Provide supplementary food during the breeding season
Relevance (R): 2 studies in the evidence base focus on skuas, 14 on other seabirds and 0 on other birds. Strength (S): The evidence base was comprised of 16 studies. Of these 10 were considered to have a good sample size, and 14 had a clear metric for effectiveness. Transparency (T): 16 studies included were published and peer-reviewed, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 13 had a published methodology, and 4 justified their rationale.
Translocate the population to a more suitable breeding area
Relevance (R): 0 studies in the evidence base focus on skuas, 15 on other seabirds and 0 on other birds. Strength (S): The evidence base was comprised of 15 studies. Of these 13 were considered to have a good sample size, and 9 had a clear metric for effectiveness. Transparency (T): 14 studies included were published and peer-reviewed, of which 1 were literature reviews or meta-analyses, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 11 had a published methodology, and 9 justified their rationale.