11 Potential actions in response to climate change: Gulls (Laridae)
In this section we list and assess possible local conservation actions that could be carried out in response to identified climate change impacts on gulls . 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.
11.1 Impact: Increased exposure to pollution and heavy metals
Summary:The effects of pollution and heavy metals are known to have serious consequences for gulls, but despite this there are no current actions that are well-researched. It is likely prevention is more effective than treatment, so the most effective action in many cases is to deter gulls (if possible) from using a heavily polluted area.| Intervention | Evidence of effectiveness | R | S | T |
|---|---|---|---|---|
| Alter habitat to encourage birds to leave an area | Very limited evidence for seabirds, and none for gulls. Several successful examples of this action in terns, but more research needed before this is considered as a viable option for gulls. | 2 | 2 | 3 |
| Reduce exposure to pollutants | This is a hypothetical action. We found no published studies assessing this action’s effectiveness. | NA | NA | NA |
| Treat sick or injured birds affected by pollution/heavy metals | This is a hypothetical action. We found no published studies assessing this action’s effectiveness. Likely to be resource intensive. | 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:
Alter habitat to encourage birds to leave an area
Relevance (R): 0 studies in the evidence base focus on gulls, 2 on other seabirds and 0 on other birds. Strength (S): The evidence base was comprised of 2 studies. Of these 2 were considered to have a good sample size, and 0 had a clear metric for effectiveness. Transparency (T): 2 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 1 justified their rationale.
11.2 Impact: Reduced area of breeding or foraging habitat
Summary:On a local scale, providing artificial nesting sites can be an effective method of counteracting this impact, though there are relatively few trials on gulls. Outside of this, if lack of habitat 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 |
|---|---|---|---|---|
| Alter habitat to encourage birds to leave an area | Few trials on seabirds and none on gulls. Several trials of this action have been successful and encouraged terns to shift breeding sites. However, this action is likely more viable for species with lower site fidelity and areas with other available breeding habitat nearby. | 2 | 2 | 3 |
| Make new colonies more attractive to encourage birds to translocate | Several different methods have been trialled extensively across other seabirds, with variable success depending on method and species. No evidence currently available for gulls, the effectiveness of decoys, acoustic cues, smells and improved habitat is currently unknown. | 2 | 4 | 3 |
| Provide artificial nesting sites | Tried extensively on many seabird species with significant benefit to many species. Artificial nesting sites have been successfully used to support kittiwake populations, but no trials currently recorded for other gull species. | 3 | 5 | 3 |
| Translocate the population to a more suitable breeding area | Known to be beneficial in other seabird groups, but evidence for gulls is limited. Several failed attempts have been recorded, and to our knowledge no successful translocations of gulls have been carried out. | 3 | 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:
Alter habitat to encourage birds to leave an area
Relevance (R): 0 studies in the evidence base focus on gulls, 2 on other seabirds and 0 on other birds. Strength (S): The evidence base was comprised of 2 studies. Of these 2 were considered to have a good sample size, and 0 had a clear metric for effectiveness. Transparency (T): 2 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 1 justified their rationale.
Make new colonies more attractive to encourage birds to translocate
Relevance (R): 0 studies in the evidence base focus on gulls, 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 artificial nesting sites
Relevance (R): 1 study in the evidence base focus on gulls, 51 on other seabirds and 1 on other birds. Strength (S): The evidence base was comprised of 54 studies. Of these 50 were considered to have a good sample size, and 33 had a clear metric for effectiveness. Transparency (T): 53 studies included were published and peer-reviewed, of which 2 were literature reviews or meta-analyses, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 33 had a published methodology, and 27 justified their rationale.
Translocate the population to a more suitable breeding area
Relevance (R): 1 study in the evidence base focus on gulls, 14 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.
11.3 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. Gulls have been successfully hand-reared, but only in very small numbers. Likely to be difficult for many species, especially those that breed in steep, inaccessible habitats. | 3 | 2 | 1 |
| Make new colonies more attractive to encourage birds to translocate | Several different methods have been trialled extensively across other seabirds, with variable success depending on method and species. No evidence currently available for gulls, the effectiveness of decoys, acoustic cues, smells and improved habitat is currently unknown. | 2 | 4 | 3 |
| Provide supplementary food during the breeding season | Trialled on many seabird species. Known to be beneficial for several gull species, but success varies. Many gulls will scavenge any available food source, so it is feasible to provide supplementary food. However, as many gull populations are already reliant on discards, there are ethical concerns regarding wide-spread use of supplemental feeding to support populations. | 3 | 4 | 3 |
| Translocate the population to a more suitable breeding area | Known to be beneficial in other seabird groups, but evidence for gulls is limited. Several failed attempts have been recorded, and to our knowledge no successful translocations of gulls have been carried out. | 3 | 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): 2 studies in the evidence base focus on gulls, 38 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 gulls, 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): 4 studies in the evidence base focus on gulls, 12 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): 1 study in the evidence base focus on gulls, 14 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.
11.4 Impact: Increased parasite load
Summary:Treatment and prevention options are available for some parasites, but they are generally rarely trialled on seabirds, and the bulk of available knowledge is based on non-seabird species. Careful consideration and planning is needed before embarking on mass-treatment of seabird populations, to avoid unintended negative consequences.| Intervention | Evidence of effectiveness | R | S | T |
|---|---|---|---|---|
| Inoculation or treatment against disease and parasites | Extensive literature exists for treatment of birds in general, but limited examples for seabirds and none for gulls. Many treatment and prevention options are available, but those that have been trialled have limited success, or even cause more harm than benefits, in wild seabird populations. The advisability of this action likely depends on the species and context in question. Endoparasite treatment in seabirds is particularly under-researched. | 1 | 5 | 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:
Inoculation or treatment against disease and parasites
Relevance (R): 0 studies in the evidence base focus on gulls, 5 on other seabirds and 29 on other birds. Strength (S): The evidence base was comprised of 34 studies. Of these 25 were considered to have a good sample size, and 22 had a clear metric for effectiveness. Transparency (T): 34 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, 21 had a published methodology, and 26 justified their rationale.
11.5 Impact: Increase in mammal predation
Summary:Invasive mammals are a major threat to many seabird populations, and as such there is a well-established literature on mammal exclusion, management and eradication detailing effective methods and case studies. However, there are more limited options when the mammalian predator in question is itself a conservation target, or is not easily managed. Nevertheless, for many situations there are several, well-researched, actions available that can benefit seabird populations effectively.| Intervention | Evidence of effectiveness | R | S | T |
|---|---|---|---|---|
| Manage/eradicate mammalian predators | Strong evidence that predator management can assist seabird populations if under heavy predation pressure, and if carried out effectively. Several successful examples in gulls. | 3 | 5 | 3 |
| Physically protect nests with barriers or enclosures | Trialled extensively on many seabird groups, mostly with success, though this varies on the species and the design of the barrier. Some trials on gulls, in particular on Audoin’s gull, have shown benefits and lowered predation. | 3 | 4 | 4 |
| Reduce predation by translocating predators | Few trials on seabirds, and none for gulls. Existing evidence suggests this action can be beneficial and reduce egg/chick predation, and could be a possible action if other forms of predator management are not viable | 2 | 4 | 3 |
| Repel predators with acoustic, chemical or visual deterrents | This is a hypothetical action. We found 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 gulls. No studies have shown this action is effective | 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 mammalian predators
Relevance (R): 2 studies in the evidence base focus on gulls, 43 on other seabirds and 4 on other birds. Strength (S): The evidence base was comprised of 52 studies. Of these 44 were considered to have a good sample size, and 34 had a clear metric for effectiveness. Transparency (T): 52 studies included were published and peer-reviewed, of which 5 were literature reviews or meta-analyses, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 24 had a published methodology, and 28 justified their rationale.
Physically protect nests with barriers or enclosures
Relevance (R): 3 studies in the evidence base focus on gulls, 9 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 gulls, 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 gulls, 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.
11.6 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 | Rarely trialled in seabirds, some benefits found in other non-seabird groups. Likely to be difficult due to large, cosmopolitan nature of many colonies; may be possible for species with spread-out, discrete nest-sites. | 1 | 3 | 2 |
| Reduce competition by removing competitor species | Trialled mostly on terns, but unclear if it is effective or not. Very scarce evidence for gulls, it has been trialled but the overall effectiveness is unclear. More research needed if this action is to be considered as a viable action. | 3 | 3 | 3 |
| Use supplementary feeding to reduce competition | This is a hypothetical action. We found no published 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 gulls, 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): 1 study in the evidence base focus on gulls, 11 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.