The International Vertebrate Pet Trade Network and Insights from US Imports of Exotic Pets

Abstract

The international trade in exotic vertebrate pets provides key social and economic benefits but also drives associated ecological, ethical, and human health impacts. However, despite its clear importance, we currently lack a full understanding of the structure of the pet trade, hampering efforts to optimize its benefits while mitigating its negative effects. In the present article, we represent and review the structure of the pet trade as a network composed of different market actors (nodes) and trade flows (links). We identify key data gaps in this network that, if filled, would enable network analyses to pinpoint targets for management. As a case study of how data-informed networks can realize this goal, we quantified spatial and temporal patterns in pets imported to the United States. Our framework and case study illustrate how network approaches can help to inform and manage the effects of the growing demand for exotic pets.

Figure 1.

A general framework of (a) the different node categories and links in the international pet trade network, which was informed by (b) our review of publications that describe the general actors and connections involved in the legal trade of vertebrates as pets. The publications we reviewed were focused on the trade in amphibians (green), fishes (orange), reptiles (purple), or amphibians and reptiles (brown). We found no studies on birds or mammals that met our review criteria (see supplemental file S1). Our network framework outlines that pet transport (panel a, dashed line) is a directional, multistage process with pets moved from one category of nodes to the next in the chain as they are collected, transported, and eventually purchased. We also identified different subcategories of nodes from our review, such as pets collected for breeding versus ranching or store versus online retailers. However, different subcategories likely exist for all stages. Not all international trade will involve all node categories and some or many nodes can be skipped, such as pets sold directly from exporters to consumers.

Figure 2.

Average species richness of pet amphibians, birds, freshwater fishes, mammals, and reptiles exported from each country to the United States during 1999 through 2013 (blue; increasing values are illustrated using an increasing color gradient) overlaid on the total richness of species native to that country that are recorded in the US pet trade (pink). Richness of traded freshwater fishes is not available by country and is instead provided across global watersheds. Marine fishes are excluded from this analysis because export values are country specific and cannot be overlaid on ocean distributions. The methods for producing these maps and links to online, interactive versions are provided in supplemental file S3.

Figure 3.

Average species richness of amphibians (green), birds (blue), fishes (orange), mammals (red), and reptiles (purple) imported to each US port of entry (air and land ports) for sale as pets during 1999 through 2013. There are strong spatial patterns in where different animal clades tend to be imported into the United States such that only a handful of ports—primarily the Dallas–Fort Worth, Los Angeles, Miami, and New York airports—import the majority of traded species (these same four ports also import the greatest quantities; see supplemental file S3). Bars are scaled relative to the maximum import richness for each animal clade, which is listed at the top of each bar in the legend. Ports whose imports constitute less than 5% of maximum import richness, and are therefore not principal ports of entry for imported pets, are plotted as grey points.

Figure 4.

Frequency distributions of incoming trade connections for pet (a) amphibians, (b) birds, (c) fishes, (d) mammals, and (e) reptiles imported to each US port of entry. The incoming connections for each port are calculated as the number of different countries a port receives shipments from for each animal clade averaged from 1999 through 2013. These right-skewed distributions indicate that most ports tend to import pets from just a single country, whereas a small number of ports (usually the Los Angeles, Miami, or New York airports) import and therefore consolidate pets from many different countries. Histograms of outgoing connections are similarly right skewed and are provided in supplementary materials S3.

Figure 5.

Temporal changes in the average number of (a) incoming and (b) outgoing trade connections during 1999 through 2013 for each animal clade. Both incoming and outgoing connections have declined over time for amphibians (green) and reptiles (purple), indicating a spatial consolidation of trade, whereas these metrics have increased in fishes (orange) and mammals (red). For birds (blue), incoming connections have decreased over time, whereas outgoing connections have increased. Best-fit lines are plotted for each animal clade on the basis of their linear relationship with time predicted from ANCOVA models (see supplementary materials S3).